A Combined Activated Sludge-Filtration-Ozonation Process for Abattoir

Wastewater Treatment

Pello Alfonso-Muniozguren1 Judy Lee1 Madeleine Bussemaker1 Ralph Chadeesingh1

Caryn Jones2 David Oakley3 Devendra Saroj2

1Chemical and Process Engineering University of Surrey Guildford GU27XH

2 Civil and Environmental Engineering University of Surrey Guildford GU27XH

3Worldwide Industries Pte Ltd London

jyleesurreyacuk dsarojsurreyacuk

Abstract

Current industrialized livestock agriculture has one of the highest consumption of water and

producing up to ten times more polluted wastewaters in comparison to domestic sewage With the

industry growing rapidly and the wastewater varying considerably in terms of organic content and

microbial population suitable wastewater treatment methods are required to ensure the

wastewater quality meet regulations before discharge In the present study a combined lab scale

activated sludge-filtration-ozonation system was used to treat a pre-treated abattoir wastewater A

24-hour hydraulic retention time and a 13-day solid retention time were used for the activated

sludge process followed by filtration (4-7 microm) and using ozone as tertiary treatment Average

reductions of 93 and 98 were achieved for chemical oxygen demand (COD) and biological

oxygen demand (BOD) respectively obtaining final values of 128 mgL COD and 12 mgL

BOD The total suspended solids (TSS) average reduction reached 99 in the same system

reducing the final value down to 3 mgL Furthermore 98 reduction in phosphorus (P) and a

complete inactivation of total coliforms (TC) was obtained after 17 min of ozonation For total

viable counts (TVC) a drastic reduction was observed after 30 min of ozonation (6 log

inactivation) at an ozone dose of 71 mg O3L The reduction percentages reported in this study are

higher than those already reported in the literature Overall the combined process was sufficient

to meet discharge requirements without further treatment for the measured parameters (COD

BOD TSS P TC and TVC)

1 Introduction

Water pollution is becoming a worldwide concern due to new and tighter environmental

regulations and the increasing need for fresh water for the exponentially growing human

population In order to meet certain water discharge or reuse regulations the wastewater treatment

usually combines primary (pre-treatment) secondary (usually biological) and tertiary

(disinfection) treatments The type and combination of processes used are governed by the

wastewater quality and regulatory limits 1 Within the European Union (EU) standards for

discharge from urban wastewater treatment plants are subjected to 91271EEC Council Directive

and are as follow biological oxygen demand (BOD) 25 mgL chemical oxygen demand (COD)

125 mgL total suspended solids (TSS) 35 mgL phosphorus (P) 1-2 mgL 2 There are no

regulations at the EU level on water reuse for agriculture irrigation although steps are being taken

to implement a common water reuse legislation 3

The meat industry has one of the highest consumption of water 4 5 with the global animal

production requiring 2422 Gm3 of water per year and the beef cattle sector alone accounting for

almost one third of this volume 6 With the production of animal products increasing yearly 7 so

does the consumption of water This then leads to the increase in the generation of wastewater

which can vary considerably in terms of organic content and microbial population 8-11 Therefore

suitable wastewater treatment methods are required to ensure the wastewater effluent quality meet

regulations before discharge

Activated sludge process (ASP) treatment of abattoir wastewater has proved to be effective at

reducing COD BOD and TSS among other parameters 12-19 Further treatment is then required to

reduce the microbial content Disinfection includes the use of chemicals such as chlorine

peracetic acid or hydrogen peroxide as well as ultraviolet radiation (UV) and ozone 20 21

Chemical usage is usually avoided to prevent the increase in effluent toxicity and bacterial

regrowth 22 UV has also been rarely utilised as a disinfection method for abattoir wastewater

treatment because its performance efficiency is compromised when treating high turbidity and

suspended solids content waters 20 21 UV also demonstrates low efficiency in the removal of

organic matter 23 Ozone however can inactivate microorganisms without altering or increasing

the toxicity of the treated effluent 23-27 and is also an efficient virucidal agent 20 25 28-30

To the best of the authorsrsquo knowledge there are only few reports in the literature on abattoir

wastewater treatment with ozone 11 31-33 Wu and Doan 11 used a screening system to remove

particles larger than 1 mm as the only pre-treatment before ozonation reporting a 99

inactivation of total coliforms (TC) aerobic bacteria and Escherichia coli after 8 min of ozonation

with an applied ozone dose of 2309 mgmin L They also reported a reduction in COD by 107

and BOD by 236 after ozonation Millamena 31 relied on coagulation and filtration processes as

a pre-treatment method reporting a COD reduction of 575 after applying ozone to the pre-

treated samples at a rate of 12 Lmin and producing 011 g O3h The highest reduction in COD

was reported by Proesmans et al 33 where they combined a biological-ozonation system for

abattoir wastewater treatment achieving hence a 66 COD reduction after the ozonation step

With the limited literature reports on the potential of a combined biological-ozonation system at

treating abattoir wastewater the present study aims to bridge the literature gap by assessing the

use of a combined Activated sludge-Filtration-Ozonation (AFO) process to treat a heavily

polluted and highly variable quality effluent from an abattoir

2 Materials and methods

21 Abattoir wastewater

Wastewater samples were taken directly from an abattoir located in the county of Surrey UK

The wastewater contained not only animal residues (blood fat viscera manure among others)

but also onsite sewage and traces of floor cleaning products The wastewater collected was

partially treated on site by a grit removal system followed by coagulation-flocculation where

ferric chloride solution was used as a coagulant and Polygold CE662 as a flocculation agent and

processed further by dissolved air flotation This onsite pre-treated effluent will be referred to as

ldquoraw wastewaterrdquo To account for wastewater variability the abattoir effluent was sampled over a

two-month period and stored at 4degC prior to use

22 Experimental setup

The activated sludge-filtration-ozonation system used is shown in Figure 1 The abattoir

wastewater samples were fed at a rate of 1 Lday into an activated sludge reactor in a semi-batch

mode and with a solid retention time (SRT) of 13 days Once the ASP reached steady state the

effluent was filtered through filter paper of pore size ranging between 4 and 7 microm (Whatman

cellulose filters grade 595) Then 400 mL of the filtrate was exposed to 71 plusmn 17 mg O 3L

(produced with an Okamizu Food Detoxifier V2) injected from the bottom of a vertical reaction

vessel via a tube fitted with an air stone diffuser The exhaust ozone leaving the reaction vessel

was measured with Aeroqual S-200 ozone meter Ozonation was carried out at room temperature

(22degC plusmn 1) and varying exposure time from 1 to 60 min To avoid airborne contamination

ozonation experiments and subsequent sample analyses were run within a fume cabinet The

initial hydraulic retention time (HRT) of 24 h was later halved (12 h) to account for COD BOD

TSS P TC and total viable counts (TVC) variation

Figure 1 A schematic of the experimental setup

23 Analytical methods

Concentration of organic matter was measured as 5-day BOD (standard method (SM) 5210 B)

and as COD (SM 5220 D) Phosphorus (Hach Spectrophotometer Method 8114 adapted from SM

4500 P E) TSS (SM 2540 D) mixed liquor suspended solids (MLSS SM 2540 D) and mixed

liquor volatile suspended solids (MLVSS SM 2540 E) contents were also determined as well as

pH (SM 4500 H+B) Total dissolved nitrogen (Hach method 10072) ammonia (Hach method

10031) and nitrate (Hach method 8039) were measured as well Additionally TC (SM 9222 B)

and TVC (SM 9215 C) were analysed before and after ozonation to evaluate the disinfection

efficiency of the process 34 All analyses for each of the measured parameters were repeated at

least twice and the arithmetic mean of 8 samples is reported

3 Results and discussion

31 Abattoir wastewater characterisation

The average values of physicochemical characteristics of the raw wastewater collected from the

abattoir are shown in Table 1 and are similar to those found elsewhere 17 19 35 36 The averages

were calculated based on 8 samples collected over a 2-month period The variation in the COD

values were relatively small and varied between 1680 and 2047 mgL BOD values were

approximately three times lower compared to COD and varied between 466 and 786 mgL TSS

values had a slightly higher fluctuation with values ranging from 110 to 412 mgL

Table 1 Characteristics of raw wastewater collected from the abattoir The averages were calculated from

8 samples collected over a period of 2 months

Parameter Average value

COD (mgL) 1804 plusmn 204

BOD (mgL) 651 plusmn 89

TSS (mgL) 250 plusmn 90

P (mgL) 115 plusmn 25

pH 53 plusmn 01

32 Activated sludge process

Shown in Figure 2 are the values for MLSS in the ASP (24 h HRT) presented as a function of

time which increase and reach a steady state at approximately 3300 mgL MLSS in about 40

days Comparable MLSS values were obtained in a similar study by Chen and Lo 17 setting the

best operational MLSS and SRT values at 3200 mgL and 994 days respectively Moreover the

MLSS and SRT values herein obtained also fall within the range of operational parameters for

ASP recommended by the United States Environmental Protection Agency 37

Also shown in Figure 2 is the MLVSS whose values also exhibit a similar increase and plateau

pattern as observed for the MLSS It is worthy to note the low values for the MLVSS and

MLVSSMLSS ratio with the latter ranging between 026 and 032 (24 h HRT) Such low values

indicate high content of inorganic matter in the raw wastewater and is attributed to a poor abattoir

pre-treatment ie poor coagulation and flocculation Lovett et al 38 and Paboacuten and Suaacuterez

Geacutelvez 14 indicated MLVSSMLSS ratios of 065 and 072-085 respectively and the higher ratio

in the latter was attributed to a better separation of inorganic compounds before entering a

biological treatment

Figure 2 MLSS and MLVSS progress as a function of time in the ASP as well as MLVSSMLSS ratio

33 A combined activated sludge-filtration-ozonation process

Once the steady state was established for the ASP the mixed liquor from the ASP was filtered

followed by ozonation The COD and BOD of the liquid at each treatment step are plotted in

Figure 3 It can be seen that the AFO process (24 h HRT ASP) reduced the COD and BOD levels

down to 128 plusmn 41 mgL and 12 plusmn 1 mgL respectively This corresponds to an average reduction

of 929 (COD) and 981 (BOD) relative to the raw wastewater In this AFO process the 17

min of ozonation worked as a polishing step to slightly reduce the COD level while not affecting

the final BOD value In this particular case carbon was reduced almost entirely during the

biological process resulting in a reduction of 901 (COD) and 974 (BOD) The filtration step

had no significant effect on COD and BOD Increasing ozonation time did not further reduce both

COD and BOD

The highest reduction in COD found in the literature was reported by Proesmans et al 33 where

they combined a biological-ozonation system to treat abattoir wastewater They reported a higher

reduction in COD by ozonation from 89 mgL (after biological treatment) to 30 mgL (after

ozonation) However in that study an ozone concentration of up to 200 mg O3L was used This

ozone dose is three times higher than the one used in the present study The dependence of the

applied ozone dose on the COD reduction is also stated by Tripathi et al 24

The reduction of the ASP HRT from 24 h to 12 h had a minimal effect on organic load removal

where similar COD values were observed for both HRTs (Figure 3) For the BOD values

decreasing the HRT increased the BOD from 17 mgL to 32 mgL This is attributed to the

bacteria having a shorter residence time in the ASP reactor for BOD reduction (such as hard BOD

or less readily biodegradable organic matter)39 40 Although minimal this led to a decrease in the

final reduction in the AFO process for BOD when the HRT was reduced from 24 h (98) to 12 h

(97)

Figure 3 Average COD and BOD values for every step of the AFO process at 24 h and 12 h ASP HRT with

17 min ozonation time

Research however has shown the potential of ozone in reducing COD and BOD by applying it to

abattoir wastewater without a previous biological treatment 11 31

Besides removing organic matter the AFO system also efficiently reduced TSS Figure 4 depicts

a final reduction of 988 after applying 17 min ozonation to the filtrate Such a reduction is

translated into a TSS average value of 3 plusmn 2 mgL agreeing with reported values elsewhere 28 41

905 of the reduction was measured after the ASP decreasing TSS value from 250 mgL (raw

effluent) to 238 mgL (mixed liquor)

Figure 4 TSS content for every step of the AFO process at 24h and 12h ASP HRT with 17 min ozonation

time

As observed with carbon filtration by 4-7 microm pore size filter paper did not reduce TSS and

neither did increasing ozone exposure time However from the experimental results obtained

during the preliminary phase (non-steady state for the ASP) a notable reduction in all the

measured parameters (COD BOD TSS and P) was obtained after filtration compared to those

before the filtration step During this non-steady state phase COD was reduced from 270 plusmn 15

mgL to 230 plusmn 10 mgL BOD from 31 plusmn 10 mgL to 15plusmn1 TSS from 30 plusmn 3 mgL to 16 plusmn 5 mgL

and P from 17 plusmn 5 mgL to 10 plusmn 5 mgL Therefore it could be underlined that filtration could

work as a backup process along with ozonation if the ASP fails

Analysing samples from the 12 h HRT in the ASP TSS reduction after the combined system falls

to 90 in comparison to that of 24 h HRT (988) with a final value of 22 mgL after the AFO

This value is notably higher than the value of 3 mgL for the 24 h HRT A similar explanation

used to address the different BOD results could be applied to the TSS That is in the 12 h HRT

ASP bacteria had less time to degrade the solids in the raw influent leading to a higher value in

the ASP effluent (24 mgL and 60 mgL after 24 h and 12 h HRT ASP respectively) Therefore

decreasing HRT could have adversely affected the solubilisation of colloidal and particulate

BOD resulting in the increase in the final TSS 42

P analyses show post ozonation values in the order of 19 plusmn 1 mgL (984 reduction) The ASP

reduced P values down to 195 plusmn 7 mgL (83) further lowering P values to 132 plusmn 9 mgL

(885) with filtration As observed with TSS increasing ozone contact time did not further

decrease P The change in ASP HRT did not make a significant difference either

In regards to pH raw wastewater samples had a pH of around 53 while the pH throughout the

AFO process ranged between 79 and 83 agreeing with already published data 28 41 43 pH

increase could be attributed to the formation of free ammonia during the ASP and its subsequent

reaction with CO2 produced during the aerobic process This results in ammonium bicarbonate

increasing alkalinity and generating a buffering capacity in the system 9

The total dissolved nitrogen content was also measured and found a reduction of 30 (from 224 plusmn

95 mgL for raw wastewater) after the ASP and maintained at a constant value of 160 plusmn 27 mgL

throughout the rest of the process Ammonia (NH4-N) reduction also happened mainly in the

bioreactor reducing NH4-N by 22 and reaching a constant value of 116 plusmn 12 mgL during

filtration and ozonation Finally nitrate was reduced by 85 during the biological step achieving

a value of 2 plusmn 1 mgL after the ASP The ASP was not design for nitrogen removal and therefore

the efficiency obtained in the AFO was lower than those found in the literature for nitrogen

reduction 19 36 38 44

331Microbial counts

During ozonation oxidation can occur through direct reaction involving molecular ozone and

via an indirect pathway through hydroxyl radicals (OH) formed during ozone decomposition

The former selectively attacks organic compounds while the latter hydroxyl radicals reacts

non-selectively with many dissolved compounds (organic and inorganic contaminants) and

the water matrix 20 45-48 By oxidation of the specific cell wall components ozone disinfects

water and kills bacteria 48

To assess disinfection efficiency samples were analysed for TC and TVC Prior to the

ozonation step the average values of TC and TVC in the filtrate were found to be 14times104

CFU100 ml and 46times109 CFU100 ml respectively Similar values were reported in the

literature 9 18 49

3311 Total Coliforms

In this study a complete inactivation of TC (4 log reduction) was achieved after dosing

the filtrate samples with ozone at 71 plusmn 17 mg O3L for 10 minutes (Figure 5) In the

literature 1 50 it is reported that up to 6 log of bacterial inactivation (Faecal Coliforms TC

and E coli mainly) were achieved after having ozonised industrial or municipal

wastewater Additionally Figure 5 shows that within the first two minutes of ozonation

the number of TC remained constant This behaviour is attributed to the presence of a

high amount of organic matter as Arayan et al 51 reported They found no bacterial

inactivation in the first minute of ozone exposure time when using 001 and 0001

fetal bovine serum (FBS) as organic matter However when the FBS concentration was

decreased to 00001 bacterial inactivation was observed within the first minute of

ozonation In the same way Liberti et al 52 showed a sudden bacterial disinfection within

the first 01 minute with a total dissolved organic carbon value of 7 mgL which is much

lower in comparison to the carbon values reported in this study Xu et al30 also reported

the importance of organic matter on ozone demand and inactivation time

Neither filtration nor ASP HRT reduction significantly affected the final disinfection

efficiency (a complete inactivation of TC was achieved with and without filtration for

both 12 h and 24 h ASP HRT after applying ozone for 10 min)

Figure 5 TC progress as a function of ozonation exposure

The World Health Organisation (WHO) recommends less than 1000 geometric mean

number of faecal coliforms per 100 ml for unrestricted irrigation for edible crops sports

fields and public parks 53 When it comes to drinking water standards the maximum

acceptable concentration of TC is zero per 100 ml noting that for water put into bottles or

containers the limit is set at zero per 250 ml 54 Both limits were met after an ozone

contact time of 10 minutes in the AFO system

3312 Total Viable Counts

On the contrary ozone could not completely remove TVC even after increasing the

ozone exposure time up to 1 hour as seen in Figure 6 However 6 log of inactivation was

obtained when subjecting the filtrate to 30 min of ozonation The average TVC after

ozonation was 6times103 CFU100 ml Increasing ozone contact time to 1 hour did not further

inactivate TVC In references 25 30 52 similar observations were made where there were no

further changes in the FC inactivation when the ozone exposure time was increased from

2 to 10 min and from 5 to 15 min In references 55 56 increasing ozonation time from 10 to

40 min did not result in further bacterial reduction

Figure 6 TVC progress as a function of ozonation exposure

The few TVC that remained alive after 30 min of ozone exposure could be resistant to

ozone These TVC could have developed defence mechanisms against ozone and be

resistant to its oxidation 57 58[52] producing ozone resistant coatings 59 or the formation of

ozone resistant pigments and biofilms 56 Microbes could also have remained within the

suspended solids left in wastewater where the solids acted as a barrier against ozone

oxidation 55 57 The setup of the ozonation chamber may have also played a role in the

mixing and transfer efficiency of ozone in wastewater 60 resulting in a lower TVC

removal It is important to mention that after 30 min contact time with ozone all the TVC

values in the wastewater were below the drinking water limit set by the European

Commission at 100 CFUml 54

Filtration had negligible effect on TC and TVC contrary to what was reported by Liberti

et al 52 According to their report 1 log difference on bacterial inactivation was achieved

between clarified and clarified-filtered feeds when using a multilayer pressure filter (deep

bed sand filter) filled with high purity silica sand and gravel The difference between the

results could be explain by the better solid removal efficiency of the deep bed sand filter

compared to the filter paper used in the present study as well as the applied ozone dose

Liberti et al 52 used an ozone dose between 7 and 15 mg O3L while in this study a much

higher ozone dose was applied (71 mg O3L) Such a high ozone dose could have led to

the inactivation of almost all the microorganisms (lt100 CFUml) regardless the amount

of TSS before ozonation Thus comparing the amount of TSS between the 24 h ASP

HRT (24 mgL) and 12 h ASP HRT (60 mgL) no difference in the final TVC was

measured after ozonating both feeds At the same time Venosa et al 60 concluded that

filtration improves substantially coliform (total and faecal) inactivation if secondary

effluent is of poor quality while not being necessary effluent filtration before ozonation if

total COD values are already low enough In this study a negligible difference in COD

was measured between filtered (178 mgL) and non-filtered (179 mgL) feeds agreeing

with the conclusion drawn by Venosa et al 60

34 Process analysis and assessment

In the combined AFO system filtration had no significant effect on organic matter and TSS

removal while ozonation worked as a polishing step on the reduction of COD BOD and TSS

Filtration however showed the potential to reduce the aforementioned parameters for the non-

steady state ASP effluent and therefore it could work as a backup process along with ozone if

the ASP fails At the same time the ASP HRT could be further reduced with a minimal effect on

substrate (BOD) removal efficiency increasing the overall efficiency of the process

On the other hand ozone was highly effective in microorganisms inactivation reducing TC and

TVC values below drinking water standards 54 Neither filtration nor ASP HRT reduction made a

significant difference in the final disinfection efficiency considering the high disinfection

potential of ozone and the applied dose

Based on the results presented in the study and considering the possible improvements for the

ASP (eg SRT and HRT adjustment nitrogen reduction etc) and the ozonation chamber (eg

increase ozone transfer efficiency) it is reasonable to say that the combined AFO system has the

potential to reach water reuse levels or even meet drinking water standards when treating abattoir

wastewater

4 Conclusions

The experimental results obtained in the AFO system proved the process is effective in reducing

organic load as well as TSS P and microbial content

COD and BOD reduction by 93 (128 mgL) and 98 (12 mgL) respectively

TSS and P reduction by 99 (3 mgL) and 98 (19 mgL) respectively

A complete inactivation (100) of TC after 10 min of ozonation

6 log reduction of TVC after 30 min of ozonation

Additionally no appreciable difference was observed between filtered and non-filtered systems

once the ASP reached the steady state For the two ASP HRTs under investigation 24 h and 12 h

and excluding TSS values no difference was found Increasing ozonation exposure from 30

minutes to 1 hour did not improve the overall efficiency of the process

Overall the combined process was sufficient to meet discharge requirements without further

treatment for the measured parameters (COD BOD TSS P TC and TVC)

Acknowledgements

We thank Worldwide Industries Pte Ltd for financial support We also acknowledge Mr C Burt and

Mr B Gibbons for their help as well as Dr D Herrera for his comments and feedback

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sanitation of water experimentally inoculated with Escherichia coli Preventive Veterinary Medicine

2017 41 (2) 84-87

52 Liberti L Notarnicola M Lopez A Advanced Treatment For Municipal Wastewater

Reuse In Agriculture III - Ozone Disinfection Ozone Science amp Engineering 2000 22 (2) 151-166

53 Mara D Cairncross S Guidelines for the safe use of wastewater and excreta in agriculture

and aquaculture In World Health Organization Geneva 1989

54 Council Directive 9883EC on the quality of water intended for human consumption O

European Union In 1998 p 42

55 Dietrich J P Loge F J Ginn T R Basagaoglu H Inactivation of particle-associated

microorganisms in wastewater disinfection modeling of ozone and chlorine reactive diffusive

transport in polydispersed suspensions Water Research 2007 41 (10) 2189-201

56 Hess S Gallert C Sensitivity of antibiotic resistant and antibiotic susceptible Escherichia

coli Enterococcus and Staphylococcus strains against ozone Water Health 2015 13 (4) 1020-8

57 Patil S Bourke P Frias J M Tiwari B K Cullen P J Inactivation of Escherichia coli

in orange juice using ozone Innovative Food Science amp Emerging Technologies 2009 10 (4) 551-

557

58 Czekalski N Imminger S Salhi E Veljkovic M Kleffel K Drissner D Hammes F

Burgmann H von Gunten U Inactivation of Antibiotic Resistant Bacteria and Resistance Genes by

Ozone From Laboratory Experiments to Full-Scale Wastewater Treatment Environmental Science amp

Technology 2016 50 (21) 11862-11871

59 Young S B Setlow P Mechanisms of Bacillus subtilis spore resistance to and killing by

aqueous ozone Applied microbiology 2004 96 (5) 1133-42

60 Venosa A D Meckes M C Opatken E J Disinfection of filtered and unfiltered

secondary effluent in two ozone contactors Environment International 1981 4 299-311

to meet discharge requirements without further treatment for the measured parameters (COD

BOD TSS P TC and TVC)

1 Introduction

Water pollution is becoming a worldwide concern due to new and tighter environmental

regulations and the increasing need for fresh water for the exponentially growing human

population In order to meet certain water discharge or reuse regulations the wastewater treatment

usually combines primary (pre-treatment) secondary (usually biological) and tertiary

(disinfection) treatments The type and combination of processes used are governed by the

wastewater quality and regulatory limits 1 Within the European Union (EU) standards for

discharge from urban wastewater treatment plants are subjected to 91271EEC Council Directive

and are as follow biological oxygen demand (BOD) 25 mgL chemical oxygen demand (COD)

125 mgL total suspended solids (TSS) 35 mgL phosphorus (P) 1-2 mgL 2 There are no

regulations at the EU level on water reuse for agriculture irrigation although steps are being taken

to implement a common water reuse legislation 3

The meat industry has one of the highest consumption of water 4 5 with the global animal

production requiring 2422 Gm3 of water per year and the beef cattle sector alone accounting for

almost one third of this volume 6 With the production of animal products increasing yearly 7 so

does the consumption of water This then leads to the increase in the generation of wastewater

which can vary considerably in terms of organic content and microbial population 8-11 Therefore

suitable wastewater treatment methods are required to ensure the wastewater effluent quality meet

regulations before discharge

Activated sludge process (ASP) treatment of abattoir wastewater has proved to be effective at

reducing COD BOD and TSS among other parameters 12-19 Further treatment is then required to

reduce the microbial content Disinfection includes the use of chemicals such as chlorine

peracetic acid or hydrogen peroxide as well as ultraviolet radiation (UV) and ozone 20 21

Chemical usage is usually avoided to prevent the increase in effluent toxicity and bacterial

regrowth 22 UV has also been rarely utilised as a disinfection method for abattoir wastewater

treatment because its performance efficiency is compromised when treating high turbidity and

suspended solids content waters 20 21 UV also demonstrates low efficiency in the removal of

organic matter 23 Ozone however can inactivate microorganisms without altering or increasing

the toxicity of the treated effluent 23-27 and is also an efficient virucidal agent 20 25 28-30

To the best of the authorsrsquo knowledge there are only few reports in the literature on abattoir

wastewater treatment with ozone 11 31-33 Wu and Doan 11 used a screening system to remove

particles larger than 1 mm as the only pre-treatment before ozonation reporting a 99

inactivation of total coliforms (TC) aerobic bacteria and Escherichia coli after 8 min of ozonation

with an applied ozone dose of 2309 mgmin L They also reported a reduction in COD by 107

and BOD by 236 after ozonation Millamena 31 relied on coagulation and filtration processes as

a pre-treatment method reporting a COD reduction of 575 after applying ozone to the pre-

treated samples at a rate of 12 Lmin and producing 011 g O3h The highest reduction in COD

was reported by Proesmans et al 33 where they combined a biological-ozonation system for

abattoir wastewater treatment achieving hence a 66 COD reduction after the ozonation step

With the limited literature reports on the potential of a combined biological-ozonation system at

treating abattoir wastewater the present study aims to bridge the literature gap by assessing the

use of a combined Activated sludge-Filtration-Ozonation (AFO) process to treat a heavily

polluted and highly variable quality effluent from an abattoir

2 Materials and methods

21 Abattoir wastewater

Wastewater samples were taken directly from an abattoir located in the county of Surrey UK

The wastewater contained not only animal residues (blood fat viscera manure among others)

but also onsite sewage and traces of floor cleaning products The wastewater collected was

partially treated on site by a grit removal system followed by coagulation-flocculation where

ferric chloride solution was used as a coagulant and Polygold CE662 as a flocculation agent and

processed further by dissolved air flotation This onsite pre-treated effluent will be referred to as

ldquoraw wastewaterrdquo To account for wastewater variability the abattoir effluent was sampled over a

two-month period and stored at 4degC prior to use

22 Experimental setup

The activated sludge-filtration-ozonation system used is shown in Figure 1 The abattoir

wastewater samples were fed at a rate of 1 Lday into an activated sludge reactor in a semi-batch

mode and with a solid retention time (SRT) of 13 days Once the ASP reached steady state the

effluent was filtered through filter paper of pore size ranging between 4 and 7 microm (Whatman

cellulose filters grade 595) Then 400 mL of the filtrate was exposed to 71 plusmn 17 mg O 3L

(produced with an Okamizu Food Detoxifier V2) injected from the bottom of a vertical reaction

vessel via a tube fitted with an air stone diffuser The exhaust ozone leaving the reaction vessel

was measured with Aeroqual S-200 ozone meter Ozonation was carried out at room temperature

(22degC plusmn 1) and varying exposure time from 1 to 60 min To avoid airborne contamination

ozonation experiments and subsequent sample analyses were run within a fume cabinet The

initial hydraulic retention time (HRT) of 24 h was later halved (12 h) to account for COD BOD

TSS P TC and total viable counts (TVC) variation

Figure 1 A schematic of the experimental setup

23 Analytical methods

Concentration of organic matter was measured as 5-day BOD (standard method (SM) 5210 B)

and as COD (SM 5220 D) Phosphorus (Hach Spectrophotometer Method 8114 adapted from SM

4500 P E) TSS (SM 2540 D) mixed liquor suspended solids (MLSS SM 2540 D) and mixed

liquor volatile suspended solids (MLVSS SM 2540 E) contents were also determined as well as

pH (SM 4500 H+B) Total dissolved nitrogen (Hach method 10072) ammonia (Hach method

10031) and nitrate (Hach method 8039) were measured as well Additionally TC (SM 9222 B)

and TVC (SM 9215 C) were analysed before and after ozonation to evaluate the disinfection

efficiency of the process 34 All analyses for each of the measured parameters were repeated at

least twice and the arithmetic mean of 8 samples is reported

3 Results and discussion

31 Abattoir wastewater characterisation

The average values of physicochemical characteristics of the raw wastewater collected from the

abattoir are shown in Table 1 and are similar to those found elsewhere 17 19 35 36 The averages

were calculated based on 8 samples collected over a 2-month period The variation in the COD

values were relatively small and varied between 1680 and 2047 mgL BOD values were

approximately three times lower compared to COD and varied between 466 and 786 mgL TSS

values had a slightly higher fluctuation with values ranging from 110 to 412 mgL

Table 1 Characteristics of raw wastewater collected from the abattoir The averages were calculated from

8 samples collected over a period of 2 months

Parameter Average value

COD (mgL) 1804 plusmn 204

BOD (mgL) 651 plusmn 89

TSS (mgL) 250 plusmn 90

P (mgL) 115 plusmn 25

pH 53 plusmn 01

32 Activated sludge process

Shown in Figure 2 are the values for MLSS in the ASP (24 h HRT) presented as a function of

time which increase and reach a steady state at approximately 3300 mgL MLSS in about 40

days Comparable MLSS values were obtained in a similar study by Chen and Lo 17 setting the

best operational MLSS and SRT values at 3200 mgL and 994 days respectively Moreover the

MLSS and SRT values herein obtained also fall within the range of operational parameters for

ASP recommended by the United States Environmental Protection Agency 37

Also shown in Figure 2 is the MLVSS whose values also exhibit a similar increase and plateau

pattern as observed for the MLSS It is worthy to note the low values for the MLVSS and

MLVSSMLSS ratio with the latter ranging between 026 and 032 (24 h HRT) Such low values

indicate high content of inorganic matter in the raw wastewater and is attributed to a poor abattoir

pre-treatment ie poor coagulation and flocculation Lovett et al 38 and Paboacuten and Suaacuterez

Geacutelvez 14 indicated MLVSSMLSS ratios of 065 and 072-085 respectively and the higher ratio

in the latter was attributed to a better separation of inorganic compounds before entering a

biological treatment

Figure 2 MLSS and MLVSS progress as a function of time in the ASP as well as MLVSSMLSS ratio

33 A combined activated sludge-filtration-ozonation process

Once the steady state was established for the ASP the mixed liquor from the ASP was filtered

followed by ozonation The COD and BOD of the liquid at each treatment step are plotted in

Figure 3 It can be seen that the AFO process (24 h HRT ASP) reduced the COD and BOD levels

down to 128 plusmn 41 mgL and 12 plusmn 1 mgL respectively This corresponds to an average reduction

of 929 (COD) and 981 (BOD) relative to the raw wastewater In this AFO process the 17

min of ozonation worked as a polishing step to slightly reduce the COD level while not affecting

the final BOD value In this particular case carbon was reduced almost entirely during the

biological process resulting in a reduction of 901 (COD) and 974 (BOD) The filtration step

had no significant effect on COD and BOD Increasing ozonation time did not further reduce both

COD and BOD

The highest reduction in COD found in the literature was reported by Proesmans et al 33 where

they combined a biological-ozonation system to treat abattoir wastewater They reported a higher

reduction in COD by ozonation from 89 mgL (after biological treatment) to 30 mgL (after

ozonation) However in that study an ozone concentration of up to 200 mg O3L was used This

ozone dose is three times higher than the one used in the present study The dependence of the

applied ozone dose on the COD reduction is also stated by Tripathi et al 24

The reduction of the ASP HRT from 24 h to 12 h had a minimal effect on organic load removal

where similar COD values were observed for both HRTs (Figure 3) For the BOD values

decreasing the HRT increased the BOD from 17 mgL to 32 mgL This is attributed to the

bacteria having a shorter residence time in the ASP reactor for BOD reduction (such as hard BOD

or less readily biodegradable organic matter)39 40 Although minimal this led to a decrease in the

final reduction in the AFO process for BOD when the HRT was reduced from 24 h (98) to 12 h

(97)

Figure 3 Average COD and BOD values for every step of the AFO process at 24 h and 12 h ASP HRT with

17 min ozonation time

Research however has shown the potential of ozone in reducing COD and BOD by applying it to

abattoir wastewater without a previous biological treatment 11 31

Besides removing organic matter the AFO system also efficiently reduced TSS Figure 4 depicts

a final reduction of 988 after applying 17 min ozonation to the filtrate Such a reduction is

translated into a TSS average value of 3 plusmn 2 mgL agreeing with reported values elsewhere 28 41

905 of the reduction was measured after the ASP decreasing TSS value from 250 mgL (raw

effluent) to 238 mgL (mixed liquor)

Figure 4 TSS content for every step of the AFO process at 24h and 12h ASP HRT with 17 min ozonation

time

As observed with carbon filtration by 4-7 microm pore size filter paper did not reduce TSS and

neither did increasing ozone exposure time However from the experimental results obtained

during the preliminary phase (non-steady state for the ASP) a notable reduction in all the

measured parameters (COD BOD TSS and P) was obtained after filtration compared to those

before the filtration step During this non-steady state phase COD was reduced from 270 plusmn 15

mgL to 230 plusmn 10 mgL BOD from 31 plusmn 10 mgL to 15plusmn1 TSS from 30 plusmn 3 mgL to 16 plusmn 5 mgL

and P from 17 plusmn 5 mgL to 10 plusmn 5 mgL Therefore it could be underlined that filtration could

work as a backup process along with ozonation if the ASP fails

Analysing samples from the 12 h HRT in the ASP TSS reduction after the combined system falls

to 90 in comparison to that of 24 h HRT (988) with a final value of 22 mgL after the AFO

This value is notably higher than the value of 3 mgL for the 24 h HRT A similar explanation

used to address the different BOD results could be applied to the TSS That is in the 12 h HRT

ASP bacteria had less time to degrade the solids in the raw influent leading to a higher value in

the ASP effluent (24 mgL and 60 mgL after 24 h and 12 h HRT ASP respectively) Therefore

decreasing HRT could have adversely affected the solubilisation of colloidal and particulate

BOD resulting in the increase in the final TSS 42

P analyses show post ozonation values in the order of 19 plusmn 1 mgL (984 reduction) The ASP

reduced P values down to 195 plusmn 7 mgL (83) further lowering P values to 132 plusmn 9 mgL

(885) with filtration As observed with TSS increasing ozone contact time did not further

decrease P The change in ASP HRT did not make a significant difference either

In regards to pH raw wastewater samples had a pH of around 53 while the pH throughout the

AFO process ranged between 79 and 83 agreeing with already published data 28 41 43 pH

increase could be attributed to the formation of free ammonia during the ASP and its subsequent

reaction with CO2 produced during the aerobic process This results in ammonium bicarbonate

increasing alkalinity and generating a buffering capacity in the system 9

The total dissolved nitrogen content was also measured and found a reduction of 30 (from 224 plusmn

95 mgL for raw wastewater) after the ASP and maintained at a constant value of 160 plusmn 27 mgL

throughout the rest of the process Ammonia (NH4-N) reduction also happened mainly in the

bioreactor reducing NH4-N by 22 and reaching a constant value of 116 plusmn 12 mgL during

filtration and ozonation Finally nitrate was reduced by 85 during the biological step achieving

a value of 2 plusmn 1 mgL after the ASP The ASP was not design for nitrogen removal and therefore

the efficiency obtained in the AFO was lower than those found in the literature for nitrogen

reduction 19 36 38 44

331Microbial counts

During ozonation oxidation can occur through direct reaction involving molecular ozone and

via an indirect pathway through hydroxyl radicals (OH) formed during ozone decomposition

The former selectively attacks organic compounds while the latter hydroxyl radicals reacts

non-selectively with many dissolved compounds (organic and inorganic contaminants) and

the water matrix 20 45-48 By oxidation of the specific cell wall components ozone disinfects

water and kills bacteria 48

To assess disinfection efficiency samples were analysed for TC and TVC Prior to the

ozonation step the average values of TC and TVC in the filtrate were found to be 14times104

CFU100 ml and 46times109 CFU100 ml respectively Similar values were reported in the

literature 9 18 49

3311 Total Coliforms

In this study a complete inactivation of TC (4 log reduction) was achieved after dosing

the filtrate samples with ozone at 71 plusmn 17 mg O3L for 10 minutes (Figure 5) In the

literature 1 50 it is reported that up to 6 log of bacterial inactivation (Faecal Coliforms TC

and E coli mainly) were achieved after having ozonised industrial or municipal

wastewater Additionally Figure 5 shows that within the first two minutes of ozonation

the number of TC remained constant This behaviour is attributed to the presence of a

high amount of organic matter as Arayan et al 51 reported They found no bacterial

inactivation in the first minute of ozone exposure time when using 001 and 0001

fetal bovine serum (FBS) as organic matter However when the FBS concentration was

decreased to 00001 bacterial inactivation was observed within the first minute of

ozonation In the same way Liberti et al 52 showed a sudden bacterial disinfection within

the first 01 minute with a total dissolved organic carbon value of 7 mgL which is much

lower in comparison to the carbon values reported in this study Xu et al30 also reported

the importance of organic matter on ozone demand and inactivation time

Neither filtration nor ASP HRT reduction significantly affected the final disinfection

efficiency (a complete inactivation of TC was achieved with and without filtration for

both 12 h and 24 h ASP HRT after applying ozone for 10 min)

Figure 5 TC progress as a function of ozonation exposure

The World Health Organisation (WHO) recommends less than 1000 geometric mean

number of faecal coliforms per 100 ml for unrestricted irrigation for edible crops sports

fields and public parks 53 When it comes to drinking water standards the maximum

acceptable concentration of TC is zero per 100 ml noting that for water put into bottles or

containers the limit is set at zero per 250 ml 54 Both limits were met after an ozone

contact time of 10 minutes in the AFO system

3312 Total Viable Counts

On the contrary ozone could not completely remove TVC even after increasing the

ozone exposure time up to 1 hour as seen in Figure 6 However 6 log of inactivation was

obtained when subjecting the filtrate to 30 min of ozonation The average TVC after

ozonation was 6times103 CFU100 ml Increasing ozone contact time to 1 hour did not further

inactivate TVC In references 25 30 52 similar observations were made where there were no

further changes in the FC inactivation when the ozone exposure time was increased from

2 to 10 min and from 5 to 15 min In references 55 56 increasing ozonation time from 10 to

40 min did not result in further bacterial reduction

Figure 6 TVC progress as a function of ozonation exposure

The few TVC that remained alive after 30 min of ozone exposure could be resistant to

ozone These TVC could have developed defence mechanisms against ozone and be

resistant to its oxidation 57 58[52] producing ozone resistant coatings 59 or the formation of

ozone resistant pigments and biofilms 56 Microbes could also have remained within the

suspended solids left in wastewater where the solids acted as a barrier against ozone

oxidation 55 57 The setup of the ozonation chamber may have also played a role in the

mixing and transfer efficiency of ozone in wastewater 60 resulting in a lower TVC

removal It is important to mention that after 30 min contact time with ozone all the TVC

values in the wastewater were below the drinking water limit set by the European

Commission at 100 CFUml 54

Filtration had negligible effect on TC and TVC contrary to what was reported by Liberti

et al 52 According to their report 1 log difference on bacterial inactivation was achieved

between clarified and clarified-filtered feeds when using a multilayer pressure filter (deep

bed sand filter) filled with high purity silica sand and gravel The difference between the

results could be explain by the better solid removal efficiency of the deep bed sand filter

compared to the filter paper used in the present study as well as the applied ozone dose

Liberti et al 52 used an ozone dose between 7 and 15 mg O3L while in this study a much

higher ozone dose was applied (71 mg O3L) Such a high ozone dose could have led to

the inactivation of almost all the microorganisms (lt100 CFUml) regardless the amount

of TSS before ozonation Thus comparing the amount of TSS between the 24 h ASP

HRT (24 mgL) and 12 h ASP HRT (60 mgL) no difference in the final TVC was

measured after ozonating both feeds At the same time Venosa et al 60 concluded that

filtration improves substantially coliform (total and faecal) inactivation if secondary

effluent is of poor quality while not being necessary effluent filtration before ozonation if

total COD values are already low enough In this study a negligible difference in COD

was measured between filtered (178 mgL) and non-filtered (179 mgL) feeds agreeing

with the conclusion drawn by Venosa et al 60

34 Process analysis and assessment

In the combined AFO system filtration had no significant effect on organic matter and TSS

removal while ozonation worked as a polishing step on the reduction of COD BOD and TSS

Filtration however showed the potential to reduce the aforementioned parameters for the non-

steady state ASP effluent and therefore it could work as a backup process along with ozone if

the ASP fails At the same time the ASP HRT could be further reduced with a minimal effect on

substrate (BOD) removal efficiency increasing the overall efficiency of the process

On the other hand ozone was highly effective in microorganisms inactivation reducing TC and

TVC values below drinking water standards 54 Neither filtration nor ASP HRT reduction made a

significant difference in the final disinfection efficiency considering the high disinfection

potential of ozone and the applied dose

Based on the results presented in the study and considering the possible improvements for the

ASP (eg SRT and HRT adjustment nitrogen reduction etc) and the ozonation chamber (eg

increase ozone transfer efficiency) it is reasonable to say that the combined AFO system has the

potential to reach water reuse levels or even meet drinking water standards when treating abattoir

wastewater

4 Conclusions

The experimental results obtained in the AFO system proved the process is effective in reducing

organic load as well as TSS P and microbial content

COD and BOD reduction by 93 (128 mgL) and 98 (12 mgL) respectively

TSS and P reduction by 99 (3 mgL) and 98 (19 mgL) respectively

A complete inactivation (100) of TC after 10 min of ozonation

6 log reduction of TVC after 30 min of ozonation

Additionally no appreciable difference was observed between filtered and non-filtered systems

once the ASP reached the steady state For the two ASP HRTs under investigation 24 h and 12 h

and excluding TSS values no difference was found Increasing ozonation exposure from 30

minutes to 1 hour did not improve the overall efficiency of the process

Overall the combined process was sufficient to meet discharge requirements without further

treatment for the measured parameters (COD BOD TSS P TC and TVC)

Acknowledgements

We thank Worldwide Industries Pte Ltd for financial support We also acknowledge Mr C Burt and

Mr B Gibbons for their help as well as Dr D Herrera for his comments and feedback

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50 Finch G R Smith D W Ozone dose-response of Escherichia coli in activated sludge

effluent Water Research 1989 23 (8) 1017-1025

51 Arayan L Alisha W B Reyes Huynh T Hop Huy T Xuan Eun J Baek Han S Yang

Hong H Chang Suk Kim Antimicrobial effect of different concentrations of ozonate water in the

sanitation of water experimentally inoculated with Escherichia coli Preventive Veterinary Medicine

2017 41 (2) 84-87

52 Liberti L Notarnicola M Lopez A Advanced Treatment For Municipal Wastewater

Reuse In Agriculture III - Ozone Disinfection Ozone Science amp Engineering 2000 22 (2) 151-166

53 Mara D Cairncross S Guidelines for the safe use of wastewater and excreta in agriculture

and aquaculture In World Health Organization Geneva 1989

54 Council Directive 9883EC on the quality of water intended for human consumption O

European Union In 1998 p 42

55 Dietrich J P Loge F J Ginn T R Basagaoglu H Inactivation of particle-associated

microorganisms in wastewater disinfection modeling of ozone and chlorine reactive diffusive

transport in polydispersed suspensions Water Research 2007 41 (10) 2189-201

56 Hess S Gallert C Sensitivity of antibiotic resistant and antibiotic susceptible Escherichia

coli Enterococcus and Staphylococcus strains against ozone Water Health 2015 13 (4) 1020-8

57 Patil S Bourke P Frias J M Tiwari B K Cullen P J Inactivation of Escherichia coli

in orange juice using ozone Innovative Food Science amp Emerging Technologies 2009 10 (4) 551-

557

58 Czekalski N Imminger S Salhi E Veljkovic M Kleffel K Drissner D Hammes F

Burgmann H von Gunten U Inactivation of Antibiotic Resistant Bacteria and Resistance Genes by

Ozone From Laboratory Experiments to Full-Scale Wastewater Treatment Environmental Science amp

Technology 2016 50 (21) 11862-11871

59 Young S B Setlow P Mechanisms of Bacillus subtilis spore resistance to and killing by

aqueous ozone Applied microbiology 2004 96 (5) 1133-42

60 Venosa A D Meckes M C Opatken E J Disinfection of filtered and unfiltered

secondary effluent in two ozone contactors Environment International 1981 4 299-311

regrowth 22 UV has also been rarely utilised as a disinfection method for abattoir wastewater

treatment because its performance efficiency is compromised when treating high turbidity and

suspended solids content waters 20 21 UV also demonstrates low efficiency in the removal of

organic matter 23 Ozone however can inactivate microorganisms without altering or increasing

the toxicity of the treated effluent 23-27 and is also an efficient virucidal agent 20 25 28-30

To the best of the authorsrsquo knowledge there are only few reports in the literature on abattoir

wastewater treatment with ozone 11 31-33 Wu and Doan 11 used a screening system to remove

particles larger than 1 mm as the only pre-treatment before ozonation reporting a 99

inactivation of total coliforms (TC) aerobic bacteria and Escherichia coli after 8 min of ozonation

with an applied ozone dose of 2309 mgmin L They also reported a reduction in COD by 107

and BOD by 236 after ozonation Millamena 31 relied on coagulation and filtration processes as

a pre-treatment method reporting a COD reduction of 575 after applying ozone to the pre-

treated samples at a rate of 12 Lmin and producing 011 g O3h The highest reduction in COD

was reported by Proesmans et al 33 where they combined a biological-ozonation system for

abattoir wastewater treatment achieving hence a 66 COD reduction after the ozonation step

With the limited literature reports on the potential of a combined biological-ozonation system at

treating abattoir wastewater the present study aims to bridge the literature gap by assessing the

use of a combined Activated sludge-Filtration-Ozonation (AFO) process to treat a heavily

polluted and highly variable quality effluent from an abattoir

2 Materials and methods

21 Abattoir wastewater

Wastewater samples were taken directly from an abattoir located in the county of Surrey UK

The wastewater contained not only animal residues (blood fat viscera manure among others)

but also onsite sewage and traces of floor cleaning products The wastewater collected was

partially treated on site by a grit removal system followed by coagulation-flocculation where

ferric chloride solution was used as a coagulant and Polygold CE662 as a flocculation agent and

processed further by dissolved air flotation This onsite pre-treated effluent will be referred to as

ldquoraw wastewaterrdquo To account for wastewater variability the abattoir effluent was sampled over a

two-month period and stored at 4degC prior to use

22 Experimental setup

The activated sludge-filtration-ozonation system used is shown in Figure 1 The abattoir

wastewater samples were fed at a rate of 1 Lday into an activated sludge reactor in a semi-batch

mode and with a solid retention time (SRT) of 13 days Once the ASP reached steady state the

effluent was filtered through filter paper of pore size ranging between 4 and 7 microm (Whatman

cellulose filters grade 595) Then 400 mL of the filtrate was exposed to 71 plusmn 17 mg O 3L

(produced with an Okamizu Food Detoxifier V2) injected from the bottom of a vertical reaction

vessel via a tube fitted with an air stone diffuser The exhaust ozone leaving the reaction vessel

was measured with Aeroqual S-200 ozone meter Ozonation was carried out at room temperature

(22degC plusmn 1) and varying exposure time from 1 to 60 min To avoid airborne contamination

ozonation experiments and subsequent sample analyses were run within a fume cabinet The

initial hydraulic retention time (HRT) of 24 h was later halved (12 h) to account for COD BOD

TSS P TC and total viable counts (TVC) variation

Figure 1 A schematic of the experimental setup

23 Analytical methods

Concentration of organic matter was measured as 5-day BOD (standard method (SM) 5210 B)

and as COD (SM 5220 D) Phosphorus (Hach Spectrophotometer Method 8114 adapted from SM

4500 P E) TSS (SM 2540 D) mixed liquor suspended solids (MLSS SM 2540 D) and mixed

liquor volatile suspended solids (MLVSS SM 2540 E) contents were also determined as well as

pH (SM 4500 H+B) Total dissolved nitrogen (Hach method 10072) ammonia (Hach method

10031) and nitrate (Hach method 8039) were measured as well Additionally TC (SM 9222 B)

and TVC (SM 9215 C) were analysed before and after ozonation to evaluate the disinfection

efficiency of the process 34 All analyses for each of the measured parameters were repeated at

least twice and the arithmetic mean of 8 samples is reported

3 Results and discussion

31 Abattoir wastewater characterisation

The average values of physicochemical characteristics of the raw wastewater collected from the

abattoir are shown in Table 1 and are similar to those found elsewhere 17 19 35 36 The averages

were calculated based on 8 samples collected over a 2-month period The variation in the COD

values were relatively small and varied between 1680 and 2047 mgL BOD values were

approximately three times lower compared to COD and varied between 466 and 786 mgL TSS

values had a slightly higher fluctuation with values ranging from 110 to 412 mgL

Table 1 Characteristics of raw wastewater collected from the abattoir The averages were calculated from

8 samples collected over a period of 2 months

Parameter Average value

COD (mgL) 1804 plusmn 204

BOD (mgL) 651 plusmn 89

TSS (mgL) 250 plusmn 90

P (mgL) 115 plusmn 25

pH 53 plusmn 01

32 Activated sludge process

Shown in Figure 2 are the values for MLSS in the ASP (24 h HRT) presented as a function of

time which increase and reach a steady state at approximately 3300 mgL MLSS in about 40

days Comparable MLSS values were obtained in a similar study by Chen and Lo 17 setting the

best operational MLSS and SRT values at 3200 mgL and 994 days respectively Moreover the

MLSS and SRT values herein obtained also fall within the range of operational parameters for

ASP recommended by the United States Environmental Protection Agency 37

Also shown in Figure 2 is the MLVSS whose values also exhibit a similar increase and plateau

pattern as observed for the MLSS It is worthy to note the low values for the MLVSS and

MLVSSMLSS ratio with the latter ranging between 026 and 032 (24 h HRT) Such low values

indicate high content of inorganic matter in the raw wastewater and is attributed to a poor abattoir

pre-treatment ie poor coagulation and flocculation Lovett et al 38 and Paboacuten and Suaacuterez

Geacutelvez 14 indicated MLVSSMLSS ratios of 065 and 072-085 respectively and the higher ratio

in the latter was attributed to a better separation of inorganic compounds before entering a

biological treatment

Figure 2 MLSS and MLVSS progress as a function of time in the ASP as well as MLVSSMLSS ratio

33 A combined activated sludge-filtration-ozonation process

Once the steady state was established for the ASP the mixed liquor from the ASP was filtered

followed by ozonation The COD and BOD of the liquid at each treatment step are plotted in

Figure 3 It can be seen that the AFO process (24 h HRT ASP) reduced the COD and BOD levels

down to 128 plusmn 41 mgL and 12 plusmn 1 mgL respectively This corresponds to an average reduction

of 929 (COD) and 981 (BOD) relative to the raw wastewater In this AFO process the 17

min of ozonation worked as a polishing step to slightly reduce the COD level while not affecting

the final BOD value In this particular case carbon was reduced almost entirely during the

biological process resulting in a reduction of 901 (COD) and 974 (BOD) The filtration step

had no significant effect on COD and BOD Increasing ozonation time did not further reduce both

COD and BOD

The highest reduction in COD found in the literature was reported by Proesmans et al 33 where

they combined a biological-ozonation system to treat abattoir wastewater They reported a higher

reduction in COD by ozonation from 89 mgL (after biological treatment) to 30 mgL (after

ozonation) However in that study an ozone concentration of up to 200 mg O3L was used This

ozone dose is three times higher than the one used in the present study The dependence of the

applied ozone dose on the COD reduction is also stated by Tripathi et al 24

The reduction of the ASP HRT from 24 h to 12 h had a minimal effect on organic load removal

where similar COD values were observed for both HRTs (Figure 3) For the BOD values

decreasing the HRT increased the BOD from 17 mgL to 32 mgL This is attributed to the

bacteria having a shorter residence time in the ASP reactor for BOD reduction (such as hard BOD

or less readily biodegradable organic matter)39 40 Although minimal this led to a decrease in the

final reduction in the AFO process for BOD when the HRT was reduced from 24 h (98) to 12 h

(97)

Figure 3 Average COD and BOD values for every step of the AFO process at 24 h and 12 h ASP HRT with

17 min ozonation time

Research however has shown the potential of ozone in reducing COD and BOD by applying it to

abattoir wastewater without a previous biological treatment 11 31

Besides removing organic matter the AFO system also efficiently reduced TSS Figure 4 depicts

a final reduction of 988 after applying 17 min ozonation to the filtrate Such a reduction is

translated into a TSS average value of 3 plusmn 2 mgL agreeing with reported values elsewhere 28 41

905 of the reduction was measured after the ASP decreasing TSS value from 250 mgL (raw

effluent) to 238 mgL (mixed liquor)

Figure 4 TSS content for every step of the AFO process at 24h and 12h ASP HRT with 17 min ozonation

time

As observed with carbon filtration by 4-7 microm pore size filter paper did not reduce TSS and

neither did increasing ozone exposure time However from the experimental results obtained

during the preliminary phase (non-steady state for the ASP) a notable reduction in all the

measured parameters (COD BOD TSS and P) was obtained after filtration compared to those

before the filtration step During this non-steady state phase COD was reduced from 270 plusmn 15

mgL to 230 plusmn 10 mgL BOD from 31 plusmn 10 mgL to 15plusmn1 TSS from 30 plusmn 3 mgL to 16 plusmn 5 mgL

and P from 17 plusmn 5 mgL to 10 plusmn 5 mgL Therefore it could be underlined that filtration could

work as a backup process along with ozonation if the ASP fails

Analysing samples from the 12 h HRT in the ASP TSS reduction after the combined system falls

to 90 in comparison to that of 24 h HRT (988) with a final value of 22 mgL after the AFO

This value is notably higher than the value of 3 mgL for the 24 h HRT A similar explanation

used to address the different BOD results could be applied to the TSS That is in the 12 h HRT

ASP bacteria had less time to degrade the solids in the raw influent leading to a higher value in

the ASP effluent (24 mgL and 60 mgL after 24 h and 12 h HRT ASP respectively) Therefore

decreasing HRT could have adversely affected the solubilisation of colloidal and particulate

BOD resulting in the increase in the final TSS 42

P analyses show post ozonation values in the order of 19 plusmn 1 mgL (984 reduction) The ASP

reduced P values down to 195 plusmn 7 mgL (83) further lowering P values to 132 plusmn 9 mgL

(885) with filtration As observed with TSS increasing ozone contact time did not further

decrease P The change in ASP HRT did not make a significant difference either

In regards to pH raw wastewater samples had a pH of around 53 while the pH throughout the

AFO process ranged between 79 and 83 agreeing with already published data 28 41 43 pH

increase could be attributed to the formation of free ammonia during the ASP and its subsequent

reaction with CO2 produced during the aerobic process This results in ammonium bicarbonate

increasing alkalinity and generating a buffering capacity in the system 9

The total dissolved nitrogen content was also measured and found a reduction of 30 (from 224 plusmn

95 mgL for raw wastewater) after the ASP and maintained at a constant value of 160 plusmn 27 mgL

throughout the rest of the process Ammonia (NH4-N) reduction also happened mainly in the

bioreactor reducing NH4-N by 22 and reaching a constant value of 116 plusmn 12 mgL during

filtration and ozonation Finally nitrate was reduced by 85 during the biological step achieving

a value of 2 plusmn 1 mgL after the ASP The ASP was not design for nitrogen removal and therefore

the efficiency obtained in the AFO was lower than those found in the literature for nitrogen

reduction 19 36 38 44

331Microbial counts

During ozonation oxidation can occur through direct reaction involving molecular ozone and

via an indirect pathway through hydroxyl radicals (OH) formed during ozone decomposition

The former selectively attacks organic compounds while the latter hydroxyl radicals reacts

non-selectively with many dissolved compounds (organic and inorganic contaminants) and

the water matrix 20 45-48 By oxidation of the specific cell wall components ozone disinfects

water and kills bacteria 48

To assess disinfection efficiency samples were analysed for TC and TVC Prior to the

ozonation step the average values of TC and TVC in the filtrate were found to be 14times104

CFU100 ml and 46times109 CFU100 ml respectively Similar values were reported in the

literature 9 18 49

3311 Total Coliforms

In this study a complete inactivation of TC (4 log reduction) was achieved after dosing

the filtrate samples with ozone at 71 plusmn 17 mg O3L for 10 minutes (Figure 5) In the

literature 1 50 it is reported that up to 6 log of bacterial inactivation (Faecal Coliforms TC

and E coli mainly) were achieved after having ozonised industrial or municipal

wastewater Additionally Figure 5 shows that within the first two minutes of ozonation

the number of TC remained constant This behaviour is attributed to the presence of a

high amount of organic matter as Arayan et al 51 reported They found no bacterial

inactivation in the first minute of ozone exposure time when using 001 and 0001

fetal bovine serum (FBS) as organic matter However when the FBS concentration was

decreased to 00001 bacterial inactivation was observed within the first minute of

ozonation In the same way Liberti et al 52 showed a sudden bacterial disinfection within

the first 01 minute with a total dissolved organic carbon value of 7 mgL which is much

lower in comparison to the carbon values reported in this study Xu et al30 also reported

the importance of organic matter on ozone demand and inactivation time

Neither filtration nor ASP HRT reduction significantly affected the final disinfection

efficiency (a complete inactivation of TC was achieved with and without filtration for

both 12 h and 24 h ASP HRT after applying ozone for 10 min)

Figure 5 TC progress as a function of ozonation exposure

The World Health Organisation (WHO) recommends less than 1000 geometric mean

number of faecal coliforms per 100 ml for unrestricted irrigation for edible crops sports

fields and public parks 53 When it comes to drinking water standards the maximum

acceptable concentration of TC is zero per 100 ml noting that for water put into bottles or

containers the limit is set at zero per 250 ml 54 Both limits were met after an ozone

contact time of 10 minutes in the AFO system

3312 Total Viable Counts

On the contrary ozone could not completely remove TVC even after increasing the

ozone exposure time up to 1 hour as seen in Figure 6 However 6 log of inactivation was

obtained when subjecting the filtrate to 30 min of ozonation The average TVC after

ozonation was 6times103 CFU100 ml Increasing ozone contact time to 1 hour did not further

inactivate TVC In references 25 30 52 similar observations were made where there were no

further changes in the FC inactivation when the ozone exposure time was increased from

2 to 10 min and from 5 to 15 min In references 55 56 increasing ozonation time from 10 to

40 min did not result in further bacterial reduction

Figure 6 TVC progress as a function of ozonation exposure

The few TVC that remained alive after 30 min of ozone exposure could be resistant to

ozone These TVC could have developed defence mechanisms against ozone and be

resistant to its oxidation 57 58[52] producing ozone resistant coatings 59 or the formation of

ozone resistant pigments and biofilms 56 Microbes could also have remained within the

suspended solids left in wastewater where the solids acted as a barrier against ozone

oxidation 55 57 The setup of the ozonation chamber may have also played a role in the

mixing and transfer efficiency of ozone in wastewater 60 resulting in a lower TVC

removal It is important to mention that after 30 min contact time with ozone all the TVC

values in the wastewater were below the drinking water limit set by the European

Commission at 100 CFUml 54

Filtration had negligible effect on TC and TVC contrary to what was reported by Liberti

et al 52 According to their report 1 log difference on bacterial inactivation was achieved

between clarified and clarified-filtered feeds when using a multilayer pressure filter (deep

bed sand filter) filled with high purity silica sand and gravel The difference between the

results could be explain by the better solid removal efficiency of the deep bed sand filter

compared to the filter paper used in the present study as well as the applied ozone dose

Liberti et al 52 used an ozone dose between 7 and 15 mg O3L while in this study a much

higher ozone dose was applied (71 mg O3L) Such a high ozone dose could have led to

the inactivation of almost all the microorganisms (lt100 CFUml) regardless the amount

of TSS before ozonation Thus comparing the amount of TSS between the 24 h ASP

HRT (24 mgL) and 12 h ASP HRT (60 mgL) no difference in the final TVC was

measured after ozonating both feeds At the same time Venosa et al 60 concluded that

filtration improves substantially coliform (total and faecal) inactivation if secondary

effluent is of poor quality while not being necessary effluent filtration before ozonation if

total COD values are already low enough In this study a negligible difference in COD

was measured between filtered (178 mgL) and non-filtered (179 mgL) feeds agreeing

with the conclusion drawn by Venosa et al 60

34 Process analysis and assessment

In the combined AFO system filtration had no significant effect on organic matter and TSS

removal while ozonation worked as a polishing step on the reduction of COD BOD and TSS

Filtration however showed the potential to reduce the aforementioned parameters for the non-

steady state ASP effluent and therefore it could work as a backup process along with ozone if

the ASP fails At the same time the ASP HRT could be further reduced with a minimal effect on

substrate (BOD) removal efficiency increasing the overall efficiency of the process

On the other hand ozone was highly effective in microorganisms inactivation reducing TC and

TVC values below drinking water standards 54 Neither filtration nor ASP HRT reduction made a

significant difference in the final disinfection efficiency considering the high disinfection

potential of ozone and the applied dose

Based on the results presented in the study and considering the possible improvements for the

ASP (eg SRT and HRT adjustment nitrogen reduction etc) and the ozonation chamber (eg

increase ozone transfer efficiency) it is reasonable to say that the combined AFO system has the

potential to reach water reuse levels or even meet drinking water standards when treating abattoir

wastewater

4 Conclusions

The experimental results obtained in the AFO system proved the process is effective in reducing

organic load as well as TSS P and microbial content

COD and BOD reduction by 93 (128 mgL) and 98 (12 mgL) respectively

TSS and P reduction by 99 (3 mgL) and 98 (19 mgL) respectively

A complete inactivation (100) of TC after 10 min of ozonation

6 log reduction of TVC after 30 min of ozonation

Additionally no appreciable difference was observed between filtered and non-filtered systems

once the ASP reached the steady state For the two ASP HRTs under investigation 24 h and 12 h

and excluding TSS values no difference was found Increasing ozonation exposure from 30

minutes to 1 hour did not improve the overall efficiency of the process

Overall the combined process was sufficient to meet discharge requirements without further

treatment for the measured parameters (COD BOD TSS P TC and TVC)

Acknowledgements

We thank Worldwide Industries Pte Ltd for financial support We also acknowledge Mr C Burt and

Mr B Gibbons for their help as well as Dr D Herrera for his comments and feedback

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in Ontario Canada Canadian biosystems engineering 2001 53 (6) 9-18

50 Finch G R Smith D W Ozone dose-response of Escherichia coli in activated sludge

effluent Water Research 1989 23 (8) 1017-1025

51 Arayan L Alisha W B Reyes Huynh T Hop Huy T Xuan Eun J Baek Han S Yang

Hong H Chang Suk Kim Antimicrobial effect of different concentrations of ozonate water in the

sanitation of water experimentally inoculated with Escherichia coli Preventive Veterinary Medicine

2017 41 (2) 84-87

52 Liberti L Notarnicola M Lopez A Advanced Treatment For Municipal Wastewater

Reuse In Agriculture III - Ozone Disinfection Ozone Science amp Engineering 2000 22 (2) 151-166

53 Mara D Cairncross S Guidelines for the safe use of wastewater and excreta in agriculture

and aquaculture In World Health Organization Geneva 1989

54 Council Directive 9883EC on the quality of water intended for human consumption O

European Union In 1998 p 42

55 Dietrich J P Loge F J Ginn T R Basagaoglu H Inactivation of particle-associated

microorganisms in wastewater disinfection modeling of ozone and chlorine reactive diffusive

transport in polydispersed suspensions Water Research 2007 41 (10) 2189-201

56 Hess S Gallert C Sensitivity of antibiotic resistant and antibiotic susceptible Escherichia

coli Enterococcus and Staphylococcus strains against ozone Water Health 2015 13 (4) 1020-8

57 Patil S Bourke P Frias J M Tiwari B K Cullen P J Inactivation of Escherichia coli

in orange juice using ozone Innovative Food Science amp Emerging Technologies 2009 10 (4) 551-

557

58 Czekalski N Imminger S Salhi E Veljkovic M Kleffel K Drissner D Hammes F

Burgmann H von Gunten U Inactivation of Antibiotic Resistant Bacteria and Resistance Genes by

Ozone From Laboratory Experiments to Full-Scale Wastewater Treatment Environmental Science amp

Technology 2016 50 (21) 11862-11871

59 Young S B Setlow P Mechanisms of Bacillus subtilis spore resistance to and killing by

aqueous ozone Applied microbiology 2004 96 (5) 1133-42

60 Venosa A D Meckes M C Opatken E J Disinfection of filtered and unfiltered

secondary effluent in two ozone contactors Environment International 1981 4 299-311

processed further by dissolved air flotation This onsite pre-treated effluent will be referred to as

ldquoraw wastewaterrdquo To account for wastewater variability the abattoir effluent was sampled over a

two-month period and stored at 4degC prior to use

22 Experimental setup

The activated sludge-filtration-ozonation system used is shown in Figure 1 The abattoir

wastewater samples were fed at a rate of 1 Lday into an activated sludge reactor in a semi-batch

mode and with a solid retention time (SRT) of 13 days Once the ASP reached steady state the

effluent was filtered through filter paper of pore size ranging between 4 and 7 microm (Whatman

cellulose filters grade 595) Then 400 mL of the filtrate was exposed to 71 plusmn 17 mg O 3L

(produced with an Okamizu Food Detoxifier V2) injected from the bottom of a vertical reaction

vessel via a tube fitted with an air stone diffuser The exhaust ozone leaving the reaction vessel

was measured with Aeroqual S-200 ozone meter Ozonation was carried out at room temperature

(22degC plusmn 1) and varying exposure time from 1 to 60 min To avoid airborne contamination

ozonation experiments and subsequent sample analyses were run within a fume cabinet The

initial hydraulic retention time (HRT) of 24 h was later halved (12 h) to account for COD BOD

TSS P TC and total viable counts (TVC) variation

Figure 1 A schematic of the experimental setup

23 Analytical methods

Concentration of organic matter was measured as 5-day BOD (standard method (SM) 5210 B)

and as COD (SM 5220 D) Phosphorus (Hach Spectrophotometer Method 8114 adapted from SM

4500 P E) TSS (SM 2540 D) mixed liquor suspended solids (MLSS SM 2540 D) and mixed

liquor volatile suspended solids (MLVSS SM 2540 E) contents were also determined as well as

pH (SM 4500 H+B) Total dissolved nitrogen (Hach method 10072) ammonia (Hach method

10031) and nitrate (Hach method 8039) were measured as well Additionally TC (SM 9222 B)

and TVC (SM 9215 C) were analysed before and after ozonation to evaluate the disinfection

efficiency of the process 34 All analyses for each of the measured parameters were repeated at

least twice and the arithmetic mean of 8 samples is reported

3 Results and discussion

31 Abattoir wastewater characterisation

The average values of physicochemical characteristics of the raw wastewater collected from the

abattoir are shown in Table 1 and are similar to those found elsewhere 17 19 35 36 The averages

were calculated based on 8 samples collected over a 2-month period The variation in the COD

values were relatively small and varied between 1680 and 2047 mgL BOD values were

approximately three times lower compared to COD and varied between 466 and 786 mgL TSS

values had a slightly higher fluctuation with values ranging from 110 to 412 mgL

Table 1 Characteristics of raw wastewater collected from the abattoir The averages were calculated from

8 samples collected over a period of 2 months

Parameter Average value

COD (mgL) 1804 plusmn 204

BOD (mgL) 651 plusmn 89

TSS (mgL) 250 plusmn 90

P (mgL) 115 plusmn 25

pH 53 plusmn 01

32 Activated sludge process

Shown in Figure 2 are the values for MLSS in the ASP (24 h HRT) presented as a function of

time which increase and reach a steady state at approximately 3300 mgL MLSS in about 40

days Comparable MLSS values were obtained in a similar study by Chen and Lo 17 setting the

best operational MLSS and SRT values at 3200 mgL and 994 days respectively Moreover the

MLSS and SRT values herein obtained also fall within the range of operational parameters for

ASP recommended by the United States Environmental Protection Agency 37

Also shown in Figure 2 is the MLVSS whose values also exhibit a similar increase and plateau

pattern as observed for the MLSS It is worthy to note the low values for the MLVSS and

MLVSSMLSS ratio with the latter ranging between 026 and 032 (24 h HRT) Such low values

indicate high content of inorganic matter in the raw wastewater and is attributed to a poor abattoir

pre-treatment ie poor coagulation and flocculation Lovett et al 38 and Paboacuten and Suaacuterez

Geacutelvez 14 indicated MLVSSMLSS ratios of 065 and 072-085 respectively and the higher ratio

in the latter was attributed to a better separation of inorganic compounds before entering a

biological treatment

Figure 2 MLSS and MLVSS progress as a function of time in the ASP as well as MLVSSMLSS ratio

33 A combined activated sludge-filtration-ozonation process

Once the steady state was established for the ASP the mixed liquor from the ASP was filtered

followed by ozonation The COD and BOD of the liquid at each treatment step are plotted in

Figure 3 It can be seen that the AFO process (24 h HRT ASP) reduced the COD and BOD levels

down to 128 plusmn 41 mgL and 12 plusmn 1 mgL respectively This corresponds to an average reduction

of 929 (COD) and 981 (BOD) relative to the raw wastewater In this AFO process the 17

min of ozonation worked as a polishing step to slightly reduce the COD level while not affecting

the final BOD value In this particular case carbon was reduced almost entirely during the

biological process resulting in a reduction of 901 (COD) and 974 (BOD) The filtration step

had no significant effect on COD and BOD Increasing ozonation time did not further reduce both

COD and BOD

The highest reduction in COD found in the literature was reported by Proesmans et al 33 where

they combined a biological-ozonation system to treat abattoir wastewater They reported a higher

reduction in COD by ozonation from 89 mgL (after biological treatment) to 30 mgL (after

ozonation) However in that study an ozone concentration of up to 200 mg O3L was used This

ozone dose is three times higher than the one used in the present study The dependence of the

applied ozone dose on the COD reduction is also stated by Tripathi et al 24

The reduction of the ASP HRT from 24 h to 12 h had a minimal effect on organic load removal

where similar COD values were observed for both HRTs (Figure 3) For the BOD values

decreasing the HRT increased the BOD from 17 mgL to 32 mgL This is attributed to the

bacteria having a shorter residence time in the ASP reactor for BOD reduction (such as hard BOD

or less readily biodegradable organic matter)39 40 Although minimal this led to a decrease in the

final reduction in the AFO process for BOD when the HRT was reduced from 24 h (98) to 12 h

(97)

Figure 3 Average COD and BOD values for every step of the AFO process at 24 h and 12 h ASP HRT with

17 min ozonation time

Research however has shown the potential of ozone in reducing COD and BOD by applying it to

abattoir wastewater without a previous biological treatment 11 31

Besides removing organic matter the AFO system also efficiently reduced TSS Figure 4 depicts

a final reduction of 988 after applying 17 min ozonation to the filtrate Such a reduction is

translated into a TSS average value of 3 plusmn 2 mgL agreeing with reported values elsewhere 28 41

905 of the reduction was measured after the ASP decreasing TSS value from 250 mgL (raw

effluent) to 238 mgL (mixed liquor)

Figure 4 TSS content for every step of the AFO process at 24h and 12h ASP HRT with 17 min ozonation

time

As observed with carbon filtration by 4-7 microm pore size filter paper did not reduce TSS and

neither did increasing ozone exposure time However from the experimental results obtained

during the preliminary phase (non-steady state for the ASP) a notable reduction in all the

measured parameters (COD BOD TSS and P) was obtained after filtration compared to those

before the filtration step During this non-steady state phase COD was reduced from 270 plusmn 15

mgL to 230 plusmn 10 mgL BOD from 31 plusmn 10 mgL to 15plusmn1 TSS from 30 plusmn 3 mgL to 16 plusmn 5 mgL

and P from 17 plusmn 5 mgL to 10 plusmn 5 mgL Therefore it could be underlined that filtration could

work as a backup process along with ozonation if the ASP fails

Analysing samples from the 12 h HRT in the ASP TSS reduction after the combined system falls

to 90 in comparison to that of 24 h HRT (988) with a final value of 22 mgL after the AFO

This value is notably higher than the value of 3 mgL for the 24 h HRT A similar explanation

used to address the different BOD results could be applied to the TSS That is in the 12 h HRT

ASP bacteria had less time to degrade the solids in the raw influent leading to a higher value in

the ASP effluent (24 mgL and 60 mgL after 24 h and 12 h HRT ASP respectively) Therefore

decreasing HRT could have adversely affected the solubilisation of colloidal and particulate

BOD resulting in the increase in the final TSS 42

P analyses show post ozonation values in the order of 19 plusmn 1 mgL (984 reduction) The ASP

reduced P values down to 195 plusmn 7 mgL (83) further lowering P values to 132 plusmn 9 mgL

(885) with filtration As observed with TSS increasing ozone contact time did not further

decrease P The change in ASP HRT did not make a significant difference either

In regards to pH raw wastewater samples had a pH of around 53 while the pH throughout the

AFO process ranged between 79 and 83 agreeing with already published data 28 41 43 pH

increase could be attributed to the formation of free ammonia during the ASP and its subsequent

reaction with CO2 produced during the aerobic process This results in ammonium bicarbonate

increasing alkalinity and generating a buffering capacity in the system 9

The total dissolved nitrogen content was also measured and found a reduction of 30 (from 224 plusmn

95 mgL for raw wastewater) after the ASP and maintained at a constant value of 160 plusmn 27 mgL

throughout the rest of the process Ammonia (NH4-N) reduction also happened mainly in the

bioreactor reducing NH4-N by 22 and reaching a constant value of 116 plusmn 12 mgL during

filtration and ozonation Finally nitrate was reduced by 85 during the biological step achieving

a value of 2 plusmn 1 mgL after the ASP The ASP was not design for nitrogen removal and therefore

the efficiency obtained in the AFO was lower than those found in the literature for nitrogen

reduction 19 36 38 44

331Microbial counts

During ozonation oxidation can occur through direct reaction involving molecular ozone and

via an indirect pathway through hydroxyl radicals (OH) formed during ozone decomposition

The former selectively attacks organic compounds while the latter hydroxyl radicals reacts

non-selectively with many dissolved compounds (organic and inorganic contaminants) and

the water matrix 20 45-48 By oxidation of the specific cell wall components ozone disinfects

water and kills bacteria 48

To assess disinfection efficiency samples were analysed for TC and TVC Prior to the

ozonation step the average values of TC and TVC in the filtrate were found to be 14times104

CFU100 ml and 46times109 CFU100 ml respectively Similar values were reported in the

literature 9 18 49

3311 Total Coliforms

In this study a complete inactivation of TC (4 log reduction) was achieved after dosing

the filtrate samples with ozone at 71 plusmn 17 mg O3L for 10 minutes (Figure 5) In the

literature 1 50 it is reported that up to 6 log of bacterial inactivation (Faecal Coliforms TC

and E coli mainly) were achieved after having ozonised industrial or municipal

wastewater Additionally Figure 5 shows that within the first two minutes of ozonation

the number of TC remained constant This behaviour is attributed to the presence of a

high amount of organic matter as Arayan et al 51 reported They found no bacterial

inactivation in the first minute of ozone exposure time when using 001 and 0001

fetal bovine serum (FBS) as organic matter However when the FBS concentration was

decreased to 00001 bacterial inactivation was observed within the first minute of

ozonation In the same way Liberti et al 52 showed a sudden bacterial disinfection within

the first 01 minute with a total dissolved organic carbon value of 7 mgL which is much

lower in comparison to the carbon values reported in this study Xu et al30 also reported

the importance of organic matter on ozone demand and inactivation time

Neither filtration nor ASP HRT reduction significantly affected the final disinfection

efficiency (a complete inactivation of TC was achieved with and without filtration for

both 12 h and 24 h ASP HRT after applying ozone for 10 min)

Figure 5 TC progress as a function of ozonation exposure

The World Health Organisation (WHO) recommends less than 1000 geometric mean

number of faecal coliforms per 100 ml for unrestricted irrigation for edible crops sports

fields and public parks 53 When it comes to drinking water standards the maximum

acceptable concentration of TC is zero per 100 ml noting that for water put into bottles or

containers the limit is set at zero per 250 ml 54 Both limits were met after an ozone

contact time of 10 minutes in the AFO system

3312 Total Viable Counts

On the contrary ozone could not completely remove TVC even after increasing the

ozone exposure time up to 1 hour as seen in Figure 6 However 6 log of inactivation was

obtained when subjecting the filtrate to 30 min of ozonation The average TVC after

ozonation was 6times103 CFU100 ml Increasing ozone contact time to 1 hour did not further

inactivate TVC In references 25 30 52 similar observations were made where there were no

further changes in the FC inactivation when the ozone exposure time was increased from

2 to 10 min and from 5 to 15 min In references 55 56 increasing ozonation time from 10 to

40 min did not result in further bacterial reduction

Figure 6 TVC progress as a function of ozonation exposure

The few TVC that remained alive after 30 min of ozone exposure could be resistant to

ozone These TVC could have developed defence mechanisms against ozone and be

resistant to its oxidation 57 58[52] producing ozone resistant coatings 59 or the formation of

ozone resistant pigments and biofilms 56 Microbes could also have remained within the

suspended solids left in wastewater where the solids acted as a barrier against ozone

oxidation 55 57 The setup of the ozonation chamber may have also played a role in the

mixing and transfer efficiency of ozone in wastewater 60 resulting in a lower TVC

removal It is important to mention that after 30 min contact time with ozone all the TVC

values in the wastewater were below the drinking water limit set by the European

Commission at 100 CFUml 54

Filtration had negligible effect on TC and TVC contrary to what was reported by Liberti

et al 52 According to their report 1 log difference on bacterial inactivation was achieved

between clarified and clarified-filtered feeds when using a multilayer pressure filter (deep

bed sand filter) filled with high purity silica sand and gravel The difference between the

results could be explain by the better solid removal efficiency of the deep bed sand filter

compared to the filter paper used in the present study as well as the applied ozone dose

Liberti et al 52 used an ozone dose between 7 and 15 mg O3L while in this study a much

higher ozone dose was applied (71 mg O3L) Such a high ozone dose could have led to

the inactivation of almost all the microorganisms (lt100 CFUml) regardless the amount

of TSS before ozonation Thus comparing the amount of TSS between the 24 h ASP

HRT (24 mgL) and 12 h ASP HRT (60 mgL) no difference in the final TVC was

measured after ozonating both feeds At the same time Venosa et al 60 concluded that

filtration improves substantially coliform (total and faecal) inactivation if secondary

effluent is of poor quality while not being necessary effluent filtration before ozonation if

total COD values are already low enough In this study a negligible difference in COD

was measured between filtered (178 mgL) and non-filtered (179 mgL) feeds agreeing

with the conclusion drawn by Venosa et al 60

34 Process analysis and assessment

In the combined AFO system filtration had no significant effect on organic matter and TSS

removal while ozonation worked as a polishing step on the reduction of COD BOD and TSS

Filtration however showed the potential to reduce the aforementioned parameters for the non-

steady state ASP effluent and therefore it could work as a backup process along with ozone if

the ASP fails At the same time the ASP HRT could be further reduced with a minimal effect on

substrate (BOD) removal efficiency increasing the overall efficiency of the process

On the other hand ozone was highly effective in microorganisms inactivation reducing TC and

TVC values below drinking water standards 54 Neither filtration nor ASP HRT reduction made a

significant difference in the final disinfection efficiency considering the high disinfection

potential of ozone and the applied dose

Based on the results presented in the study and considering the possible improvements for the

ASP (eg SRT and HRT adjustment nitrogen reduction etc) and the ozonation chamber (eg

increase ozone transfer efficiency) it is reasonable to say that the combined AFO system has the

potential to reach water reuse levels or even meet drinking water standards when treating abattoir

wastewater

4 Conclusions

The experimental results obtained in the AFO system proved the process is effective in reducing

organic load as well as TSS P and microbial content

COD and BOD reduction by 93 (128 mgL) and 98 (12 mgL) respectively

TSS and P reduction by 99 (3 mgL) and 98 (19 mgL) respectively

A complete inactivation (100) of TC after 10 min of ozonation

6 log reduction of TVC after 30 min of ozonation

Additionally no appreciable difference was observed between filtered and non-filtered systems

once the ASP reached the steady state For the two ASP HRTs under investigation 24 h and 12 h

and excluding TSS values no difference was found Increasing ozonation exposure from 30

minutes to 1 hour did not improve the overall efficiency of the process

Overall the combined process was sufficient to meet discharge requirements without further

treatment for the measured parameters (COD BOD TSS P TC and TVC)

Acknowledgements

We thank Worldwide Industries Pte Ltd for financial support We also acknowledge Mr C Burt and

Mr B Gibbons for their help as well as Dr D Herrera for his comments and feedback

References

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8 Arvanitoyannis I S Ladas D Meat waste treatment methods and potential uses

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the Anaerobic Treatment of Slaughterhouse Wastewater Journal of Bioremediation amp

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10 Bustillo-Lecompte C F Mehrvar M Treatment of an actual slaughterhouse wastewater by

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11 Wu J Doan H Disinfection of recycled red-meat-processing wastewater by ozone Journal

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16 Hsiao T H Huang J S Huang Y I Process kinetics of an activated-sludge reactor

system treating poultry slaughterhouse wastewater Environ Technol 2012 33 (7-9) 829-35

17 Chen C K Lo S L Treatment of slaughterhouse wastewater using an activated

sludgecontact aeration process Water Science amp Technology 2003 47 (12) 285-292

18 Um M M Barraud O Kerouredan M Gaschet M Stalder T Oswald E Dagot C

Ploy M C Brugere H Bibbal D Comparison of the incidence of pathogenic and antibiotic-

resistant Escherichia coli strains in adult cattle and veal calf slaughterhouse effluents highlighted

different risks for public health Water Research 2016 88 30-8

19 Heddle J F Activated sludge treatment of slaughterhouse wastes with protein recovery

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peracetic acid UV and ozone after enhanced primary treatment of municipal wastewater Water

Research 2003 37 (19) 4573-4586

21 Gehr R Wright H UV disinfection of wastewater coagulated with ferric chloride

recalcitrance and fouling problems Water Science amp Technology 1998 38 (3) 15-23

22 Lazarova V Janex M L Fiksdal L Oberg C Barcina I Pommepuy M Advanced

wastewater disinfection technologies short and long term efficiency Water Science amp Technology

1998 38 (12) 109-117

23 Paraskeva P Graham N J D Treatment of a secondary municipal effluent by ozone UV

and microfiltration microbial reduction and effect on effluent quality Desalination 2005 186 (1-3)

47-56

24 Tripathi S Pathak V Tripathi D M Tripathi B D Application of ozone based

treatments of secondary effluents Bioresource Technology 2011 102 (3) 2481-6

25 Lazarova V Liechti P-A Savoye P Hausler R Ozone disinfection main parameters for

process design in wastewater treatment and reuse Journal of Water Reuse and Desalination 2013 3

(4) 337

26 Absi F Gamache F Gehr R Liechti P Nicell J Pilot plant investigation of ozone

disinfection of physico-chemically treatedmunicipal wastewater Ozone Water Wastewater Treatment

1993 1 (7) 33-42

27 Langlais B Legube B Beuffe H Dore M Study of the nature of the by-products formed

and the risks of toxicity when disinfecting a secondary effluent with ozone Water Science amp

Technology 1992 25 (12) 135-143

28 Nebel C Gottschling D Hutchinson R L McBride T J Taylor D M Pavoni J L

Tittlebaum M E Spencer H E Fleischman M Ozone disinfection of industrial municipal

secondary effluents Water pollution control federation 1974 45 (12) 2493-2507

29 Pavoni J L Tittlebaum M E Spencer H E Fleischman M Nebel C Gottschling D

Virus removal from wastewater using ozone Water and sewage works 1972 119 (12) 59-67

30 Xu P Janex M-L Savoye P Cockx A Lazarova V Wastewater disinfection by ozone

main parameters for process design Water Research 2002 36 (4) 1043-1055

31 Millamena O M Ozone treatment of slaughterhouse and laboratory wastewaters

Aquacultural Engineering 1991 11 23-31

32 Roux A Renovation of wastewater for direct re-use in an abattoir MSc thesis University of

Pretoria 1996

33 Proesmans P De Vil R Gerards R Vriends L Advanced treatment of industrial

wastewaters combination of biological treatment and ozonation Mededelingen-faculteit

landbouwkundige en toegepaste biologische wetenschappen 1997 62 (4) 1729-1736

34 APHA American Public Health Association Standard Methods for the Examination of

Water and Wastewater 20 ed Washington DC 1998

35 Al-Mutairi N Z Hamoda M F Al-Ghusain I A Performance-Based Characterization of

a Contact Stabilization Process for Slaughterhouse Wastewater Journal of Environmental Science

and Health Part A 2003 38 (10) 2287-2300

36 Fongsatitkul P Wareham D G Elefsiniotis P Charoensuk P Treatment of a

slaughterhouse wastewater effect of internal recycle rate on chemical oxygen demand total Kjeldahl

nitrogen and total phosphorus removal Environmental Technology 2011 32 (15) 1755-1759

37 Environmental Protection Agency Wastewater treatment manuals Primary secondary and

tertiary treatment Ardcavan Wexford Ireland 1997

38 Lovett D A Travers S M Davey K R Activated sludge treatment of abattoir

wastewater-I Influence of sludge age and feeding pattern Water Research 1984 18 (4) 429-434

39 Abbas H Seif H Moursy A Effect of hydraulic retention time on the activated sludge

system In Sixth International Water Technology Conference Alexandria Egypt 2001 pp 277-284

40 Zhang Y Wang X Hu M Li P Effect of hydraulic retention time (HRT) on the

biodegradation of trichloroethylene wastewater and anaerobic bacterial community in the UASB

reactor Applied microbiology biotechnology 2015 99 (4) 1977-87

41 Martiacutenez S B Peacuterez-Parra J Suay R Use of Ozone in Wastewater Treatment to Produce

Water Suitable for Irrigation Water Resources Management 2011 25 (9) 2109-2124

42 Gerardi M Settleability problems and loss of solids in the activated sludge process New

Jersey USA John Wiley and Sons 2002 179 p 2002

43 Paraskeva P Lambert S D Graham N J D Influence of Ozonation Conditions on the

Treatability of Secondary Effluents Ozone Science amp Engineering 1998 20 (2) 133-150

44 Bustillo-Lecompte C F Mehrvar M Quinones-Bolanos E Combined anaerobic-aerobic

and UVH2O2 processes for the treatment of synthetic slaughterhouse wastewater Environmental

Science and Health Part A Toxichazardous substances amp environmetal engineering 2013 48 (9)

1122-35

45 von Gunten U Ozonation of drinking water Part I Oxidation kinetics and product

formation Water Research 2003 37 (7) 1443-1467

46 Jin X Peldszus S Huck P M Reaction kinetics of selected micropollutants in ozonation

and advanced oxidation processes Water Research 2012 46 (19) 6519-30

47 Masten S J Davies S H R The use of ozonation to degrade organic contaminants in

wastewaters Environmental science amp technology 1994 28 (4) 180-185

48 Gray N F Ozone disinfection In Microbiology of waterborne diseases ElsevierAcademic

Press 2014 pp 599-615

49 Wu P F Mittal G S Characterization of provincial inspected slaughterhouse wastewater

in Ontario Canada Canadian biosystems engineering 2001 53 (6) 9-18

50 Finch G R Smith D W Ozone dose-response of Escherichia coli in activated sludge

effluent Water Research 1989 23 (8) 1017-1025

51 Arayan L Alisha W B Reyes Huynh T Hop Huy T Xuan Eun J Baek Han S Yang

Hong H Chang Suk Kim Antimicrobial effect of different concentrations of ozonate water in the

sanitation of water experimentally inoculated with Escherichia coli Preventive Veterinary Medicine

2017 41 (2) 84-87

52 Liberti L Notarnicola M Lopez A Advanced Treatment For Municipal Wastewater

Reuse In Agriculture III - Ozone Disinfection Ozone Science amp Engineering 2000 22 (2) 151-166

53 Mara D Cairncross S Guidelines for the safe use of wastewater and excreta in agriculture

and aquaculture In World Health Organization Geneva 1989

54 Council Directive 9883EC on the quality of water intended for human consumption O

European Union In 1998 p 42

55 Dietrich J P Loge F J Ginn T R Basagaoglu H Inactivation of particle-associated

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56 Hess S Gallert C Sensitivity of antibiotic resistant and antibiotic susceptible Escherichia

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in orange juice using ozone Innovative Food Science amp Emerging Technologies 2009 10 (4) 551-

557

58 Czekalski N Imminger S Salhi E Veljkovic M Kleffel K Drissner D Hammes F

Burgmann H von Gunten U Inactivation of Antibiotic Resistant Bacteria and Resistance Genes by

Ozone From Laboratory Experiments to Full-Scale Wastewater Treatment Environmental Science amp

Technology 2016 50 (21) 11862-11871

59 Young S B Setlow P Mechanisms of Bacillus subtilis spore resistance to and killing by

aqueous ozone Applied microbiology 2004 96 (5) 1133-42

60 Venosa A D Meckes M C Opatken E J Disinfection of filtered and unfiltered

secondary effluent in two ozone contactors Environment International 1981 4 299-311

Concentration of organic matter was measured as 5-day BOD (standard method (SM) 5210 B)

and as COD (SM 5220 D) Phosphorus (Hach Spectrophotometer Method 8114 adapted from SM

4500 P E) TSS (SM 2540 D) mixed liquor suspended solids (MLSS SM 2540 D) and mixed

liquor volatile suspended solids (MLVSS SM 2540 E) contents were also determined as well as

pH (SM 4500 H+B) Total dissolved nitrogen (Hach method 10072) ammonia (Hach method

10031) and nitrate (Hach method 8039) were measured as well Additionally TC (SM 9222 B)

and TVC (SM 9215 C) were analysed before and after ozonation to evaluate the disinfection

efficiency of the process 34 All analyses for each of the measured parameters were repeated at

least twice and the arithmetic mean of 8 samples is reported

3 Results and discussion

31 Abattoir wastewater characterisation

The average values of physicochemical characteristics of the raw wastewater collected from the

abattoir are shown in Table 1 and are similar to those found elsewhere 17 19 35 36 The averages

were calculated based on 8 samples collected over a 2-month period The variation in the COD

values were relatively small and varied between 1680 and 2047 mgL BOD values were

approximately three times lower compared to COD and varied between 466 and 786 mgL TSS

values had a slightly higher fluctuation with values ranging from 110 to 412 mgL

Table 1 Characteristics of raw wastewater collected from the abattoir The averages were calculated from

8 samples collected over a period of 2 months

Parameter Average value

COD (mgL) 1804 plusmn 204

BOD (mgL) 651 plusmn 89

TSS (mgL) 250 plusmn 90

P (mgL) 115 plusmn 25

pH 53 plusmn 01

32 Activated sludge process

Shown in Figure 2 are the values for MLSS in the ASP (24 h HRT) presented as a function of

time which increase and reach a steady state at approximately 3300 mgL MLSS in about 40

days Comparable MLSS values were obtained in a similar study by Chen and Lo 17 setting the

best operational MLSS and SRT values at 3200 mgL and 994 days respectively Moreover the

MLSS and SRT values herein obtained also fall within the range of operational parameters for

ASP recommended by the United States Environmental Protection Agency 37

Also shown in Figure 2 is the MLVSS whose values also exhibit a similar increase and plateau

pattern as observed for the MLSS It is worthy to note the low values for the MLVSS and

MLVSSMLSS ratio with the latter ranging between 026 and 032 (24 h HRT) Such low values

indicate high content of inorganic matter in the raw wastewater and is attributed to a poor abattoir

pre-treatment ie poor coagulation and flocculation Lovett et al 38 and Paboacuten and Suaacuterez

Geacutelvez 14 indicated MLVSSMLSS ratios of 065 and 072-085 respectively and the higher ratio

in the latter was attributed to a better separation of inorganic compounds before entering a

biological treatment

Figure 2 MLSS and MLVSS progress as a function of time in the ASP as well as MLVSSMLSS ratio

33 A combined activated sludge-filtration-ozonation process

Once the steady state was established for the ASP the mixed liquor from the ASP was filtered

followed by ozonation The COD and BOD of the liquid at each treatment step are plotted in

Figure 3 It can be seen that the AFO process (24 h HRT ASP) reduced the COD and BOD levels

down to 128 plusmn 41 mgL and 12 plusmn 1 mgL respectively This corresponds to an average reduction

of 929 (COD) and 981 (BOD) relative to the raw wastewater In this AFO process the 17

min of ozonation worked as a polishing step to slightly reduce the COD level while not affecting

the final BOD value In this particular case carbon was reduced almost entirely during the

biological process resulting in a reduction of 901 (COD) and 974 (BOD) The filtration step

had no significant effect on COD and BOD Increasing ozonation time did not further reduce both

COD and BOD

The highest reduction in COD found in the literature was reported by Proesmans et al 33 where

they combined a biological-ozonation system to treat abattoir wastewater They reported a higher

reduction in COD by ozonation from 89 mgL (after biological treatment) to 30 mgL (after

ozonation) However in that study an ozone concentration of up to 200 mg O3L was used This

ozone dose is three times higher than the one used in the present study The dependence of the

applied ozone dose on the COD reduction is also stated by Tripathi et al 24

The reduction of the ASP HRT from 24 h to 12 h had a minimal effect on organic load removal

where similar COD values were observed for both HRTs (Figure 3) For the BOD values

decreasing the HRT increased the BOD from 17 mgL to 32 mgL This is attributed to the

bacteria having a shorter residence time in the ASP reactor for BOD reduction (such as hard BOD

or less readily biodegradable organic matter)39 40 Although minimal this led to a decrease in the

final reduction in the AFO process for BOD when the HRT was reduced from 24 h (98) to 12 h

(97)

Figure 3 Average COD and BOD values for every step of the AFO process at 24 h and 12 h ASP HRT with

17 min ozonation time

Research however has shown the potential of ozone in reducing COD and BOD by applying it to

abattoir wastewater without a previous biological treatment 11 31

Besides removing organic matter the AFO system also efficiently reduced TSS Figure 4 depicts

a final reduction of 988 after applying 17 min ozonation to the filtrate Such a reduction is

translated into a TSS average value of 3 plusmn 2 mgL agreeing with reported values elsewhere 28 41

905 of the reduction was measured after the ASP decreasing TSS value from 250 mgL (raw

effluent) to 238 mgL (mixed liquor)

Figure 4 TSS content for every step of the AFO process at 24h and 12h ASP HRT with 17 min ozonation

time

As observed with carbon filtration by 4-7 microm pore size filter paper did not reduce TSS and

neither did increasing ozone exposure time However from the experimental results obtained

during the preliminary phase (non-steady state for the ASP) a notable reduction in all the

measured parameters (COD BOD TSS and P) was obtained after filtration compared to those

before the filtration step During this non-steady state phase COD was reduced from 270 plusmn 15

mgL to 230 plusmn 10 mgL BOD from 31 plusmn 10 mgL to 15plusmn1 TSS from 30 plusmn 3 mgL to 16 plusmn 5 mgL

and P from 17 plusmn 5 mgL to 10 plusmn 5 mgL Therefore it could be underlined that filtration could

work as a backup process along with ozonation if the ASP fails

Analysing samples from the 12 h HRT in the ASP TSS reduction after the combined system falls

to 90 in comparison to that of 24 h HRT (988) with a final value of 22 mgL after the AFO

This value is notably higher than the value of 3 mgL for the 24 h HRT A similar explanation

used to address the different BOD results could be applied to the TSS That is in the 12 h HRT

ASP bacteria had less time to degrade the solids in the raw influent leading to a higher value in

the ASP effluent (24 mgL and 60 mgL after 24 h and 12 h HRT ASP respectively) Therefore

decreasing HRT could have adversely affected the solubilisation of colloidal and particulate

BOD resulting in the increase in the final TSS 42

P analyses show post ozonation values in the order of 19 plusmn 1 mgL (984 reduction) The ASP

reduced P values down to 195 plusmn 7 mgL (83) further lowering P values to 132 plusmn 9 mgL

(885) with filtration As observed with TSS increasing ozone contact time did not further

decrease P The change in ASP HRT did not make a significant difference either

In regards to pH raw wastewater samples had a pH of around 53 while the pH throughout the

AFO process ranged between 79 and 83 agreeing with already published data 28 41 43 pH

increase could be attributed to the formation of free ammonia during the ASP and its subsequent

reaction with CO2 produced during the aerobic process This results in ammonium bicarbonate

increasing alkalinity and generating a buffering capacity in the system 9

The total dissolved nitrogen content was also measured and found a reduction of 30 (from 224 plusmn

95 mgL for raw wastewater) after the ASP and maintained at a constant value of 160 plusmn 27 mgL

throughout the rest of the process Ammonia (NH4-N) reduction also happened mainly in the

bioreactor reducing NH4-N by 22 and reaching a constant value of 116 plusmn 12 mgL during

filtration and ozonation Finally nitrate was reduced by 85 during the biological step achieving

a value of 2 plusmn 1 mgL after the ASP The ASP was not design for nitrogen removal and therefore

the efficiency obtained in the AFO was lower than those found in the literature for nitrogen

reduction 19 36 38 44

331Microbial counts

During ozonation oxidation can occur through direct reaction involving molecular ozone and

via an indirect pathway through hydroxyl radicals (OH) formed during ozone decomposition

The former selectively attacks organic compounds while the latter hydroxyl radicals reacts

non-selectively with many dissolved compounds (organic and inorganic contaminants) and

the water matrix 20 45-48 By oxidation of the specific cell wall components ozone disinfects

water and kills bacteria 48

To assess disinfection efficiency samples were analysed for TC and TVC Prior to the

ozonation step the average values of TC and TVC in the filtrate were found to be 14times104

CFU100 ml and 46times109 CFU100 ml respectively Similar values were reported in the

literature 9 18 49

3311 Total Coliforms

In this study a complete inactivation of TC (4 log reduction) was achieved after dosing

the filtrate samples with ozone at 71 plusmn 17 mg O3L for 10 minutes (Figure 5) In the

literature 1 50 it is reported that up to 6 log of bacterial inactivation (Faecal Coliforms TC

and E coli mainly) were achieved after having ozonised industrial or municipal

wastewater Additionally Figure 5 shows that within the first two minutes of ozonation

the number of TC remained constant This behaviour is attributed to the presence of a

high amount of organic matter as Arayan et al 51 reported They found no bacterial

inactivation in the first minute of ozone exposure time when using 001 and 0001

fetal bovine serum (FBS) as organic matter However when the FBS concentration was

decreased to 00001 bacterial inactivation was observed within the first minute of

ozonation In the same way Liberti et al 52 showed a sudden bacterial disinfection within

the first 01 minute with a total dissolved organic carbon value of 7 mgL which is much

lower in comparison to the carbon values reported in this study Xu et al30 also reported

the importance of organic matter on ozone demand and inactivation time

Neither filtration nor ASP HRT reduction significantly affected the final disinfection

efficiency (a complete inactivation of TC was achieved with and without filtration for

both 12 h and 24 h ASP HRT after applying ozone for 10 min)

Figure 5 TC progress as a function of ozonation exposure

The World Health Organisation (WHO) recommends less than 1000 geometric mean

number of faecal coliforms per 100 ml for unrestricted irrigation for edible crops sports

fields and public parks 53 When it comes to drinking water standards the maximum

acceptable concentration of TC is zero per 100 ml noting that for water put into bottles or

containers the limit is set at zero per 250 ml 54 Both limits were met after an ozone

contact time of 10 minutes in the AFO system

3312 Total Viable Counts

On the contrary ozone could not completely remove TVC even after increasing the

ozone exposure time up to 1 hour as seen in Figure 6 However 6 log of inactivation was

obtained when subjecting the filtrate to 30 min of ozonation The average TVC after

ozonation was 6times103 CFU100 ml Increasing ozone contact time to 1 hour did not further

inactivate TVC In references 25 30 52 similar observations were made where there were no

further changes in the FC inactivation when the ozone exposure time was increased from

2 to 10 min and from 5 to 15 min In references 55 56 increasing ozonation time from 10 to

40 min did not result in further bacterial reduction

Figure 6 TVC progress as a function of ozonation exposure

The few TVC that remained alive after 30 min of ozone exposure could be resistant to

ozone These TVC could have developed defence mechanisms against ozone and be

resistant to its oxidation 57 58[52] producing ozone resistant coatings 59 or the formation of

ozone resistant pigments and biofilms 56 Microbes could also have remained within the

suspended solids left in wastewater where the solids acted as a barrier against ozone

oxidation 55 57 The setup of the ozonation chamber may have also played a role in the

mixing and transfer efficiency of ozone in wastewater 60 resulting in a lower TVC

removal It is important to mention that after 30 min contact time with ozone all the TVC

values in the wastewater were below the drinking water limit set by the European

Commission at 100 CFUml 54

Filtration had negligible effect on TC and TVC contrary to what was reported by Liberti

et al 52 According to their report 1 log difference on bacterial inactivation was achieved

between clarified and clarified-filtered feeds when using a multilayer pressure filter (deep

bed sand filter) filled with high purity silica sand and gravel The difference between the

results could be explain by the better solid removal efficiency of the deep bed sand filter

compared to the filter paper used in the present study as well as the applied ozone dose

Liberti et al 52 used an ozone dose between 7 and 15 mg O3L while in this study a much

higher ozone dose was applied (71 mg O3L) Such a high ozone dose could have led to

the inactivation of almost all the microorganisms (lt100 CFUml) regardless the amount

of TSS before ozonation Thus comparing the amount of TSS between the 24 h ASP

HRT (24 mgL) and 12 h ASP HRT (60 mgL) no difference in the final TVC was

measured after ozonating both feeds At the same time Venosa et al 60 concluded that

filtration improves substantially coliform (total and faecal) inactivation if secondary

effluent is of poor quality while not being necessary effluent filtration before ozonation if

total COD values are already low enough In this study a negligible difference in COD

was measured between filtered (178 mgL) and non-filtered (179 mgL) feeds agreeing

with the conclusion drawn by Venosa et al 60

34 Process analysis and assessment

In the combined AFO system filtration had no significant effect on organic matter and TSS

removal while ozonation worked as a polishing step on the reduction of COD BOD and TSS

Filtration however showed the potential to reduce the aforementioned parameters for the non-

steady state ASP effluent and therefore it could work as a backup process along with ozone if

the ASP fails At the same time the ASP HRT could be further reduced with a minimal effect on

substrate (BOD) removal efficiency increasing the overall efficiency of the process

On the other hand ozone was highly effective in microorganisms inactivation reducing TC and

TVC values below drinking water standards 54 Neither filtration nor ASP HRT reduction made a

significant difference in the final disinfection efficiency considering the high disinfection

potential of ozone and the applied dose

Based on the results presented in the study and considering the possible improvements for the

ASP (eg SRT and HRT adjustment nitrogen reduction etc) and the ozonation chamber (eg

increase ozone transfer efficiency) it is reasonable to say that the combined AFO system has the

potential to reach water reuse levels or even meet drinking water standards when treating abattoir

wastewater

4 Conclusions

The experimental results obtained in the AFO system proved the process is effective in reducing

organic load as well as TSS P and microbial content

COD and BOD reduction by 93 (128 mgL) and 98 (12 mgL) respectively

TSS and P reduction by 99 (3 mgL) and 98 (19 mgL) respectively

A complete inactivation (100) of TC after 10 min of ozonation

6 log reduction of TVC after 30 min of ozonation

Additionally no appreciable difference was observed between filtered and non-filtered systems

once the ASP reached the steady state For the two ASP HRTs under investigation 24 h and 12 h

and excluding TSS values no difference was found Increasing ozonation exposure from 30

minutes to 1 hour did not improve the overall efficiency of the process

Overall the combined process was sufficient to meet discharge requirements without further

treatment for the measured parameters (COD BOD TSS P TC and TVC)

Acknowledgements

We thank Worldwide Industries Pte Ltd for financial support We also acknowledge Mr C Burt and

Mr B Gibbons for their help as well as Dr D Herrera for his comments and feedback

References

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8 Arvanitoyannis I S Ladas D Meat waste treatment methods and potential uses

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the Anaerobic Treatment of Slaughterhouse Wastewater Journal of Bioremediation amp

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10 Bustillo-Lecompte C F Mehrvar M Treatment of an actual slaughterhouse wastewater by

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17 Chen C K Lo S L Treatment of slaughterhouse wastewater using an activated

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resistant Escherichia coli strains in adult cattle and veal calf slaughterhouse effluents highlighted

different risks for public health Water Research 2016 88 30-8

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peracetic acid UV and ozone after enhanced primary treatment of municipal wastewater Water

Research 2003 37 (19) 4573-4586

21 Gehr R Wright H UV disinfection of wastewater coagulated with ferric chloride

recalcitrance and fouling problems Water Science amp Technology 1998 38 (3) 15-23

22 Lazarova V Janex M L Fiksdal L Oberg C Barcina I Pommepuy M Advanced

wastewater disinfection technologies short and long term efficiency Water Science amp Technology

1998 38 (12) 109-117

23 Paraskeva P Graham N J D Treatment of a secondary municipal effluent by ozone UV

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47-56

24 Tripathi S Pathak V Tripathi D M Tripathi B D Application of ozone based

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25 Lazarova V Liechti P-A Savoye P Hausler R Ozone disinfection main parameters for

process design in wastewater treatment and reuse Journal of Water Reuse and Desalination 2013 3

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1993 1 (7) 33-42

27 Langlais B Legube B Beuffe H Dore M Study of the nature of the by-products formed

and the risks of toxicity when disinfecting a secondary effluent with ozone Water Science amp

Technology 1992 25 (12) 135-143

28 Nebel C Gottschling D Hutchinson R L McBride T J Taylor D M Pavoni J L

Tittlebaum M E Spencer H E Fleischman M Ozone disinfection of industrial municipal

secondary effluents Water pollution control federation 1974 45 (12) 2493-2507

29 Pavoni J L Tittlebaum M E Spencer H E Fleischman M Nebel C Gottschling D

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main parameters for process design Water Research 2002 36 (4) 1043-1055

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Pretoria 1996

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wastewaters combination of biological treatment and ozonation Mededelingen-faculteit

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Water and Wastewater 20 ed Washington DC 1998

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tertiary treatment Ardcavan Wexford Ireland 1997

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40 Zhang Y Wang X Hu M Li P Effect of hydraulic retention time (HRT) on the

biodegradation of trichloroethylene wastewater and anaerobic bacterial community in the UASB

reactor Applied microbiology biotechnology 2015 99 (4) 1977-87

41 Martiacutenez S B Peacuterez-Parra J Suay R Use of Ozone in Wastewater Treatment to Produce

Water Suitable for Irrigation Water Resources Management 2011 25 (9) 2109-2124

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Jersey USA John Wiley and Sons 2002 179 p 2002

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Treatability of Secondary Effluents Ozone Science amp Engineering 1998 20 (2) 133-150

44 Bustillo-Lecompte C F Mehrvar M Quinones-Bolanos E Combined anaerobic-aerobic

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formation Water Research 2003 37 (7) 1443-1467

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and advanced oxidation processes Water Research 2012 46 (19) 6519-30

47 Masten S J Davies S H R The use of ozonation to degrade organic contaminants in

wastewaters Environmental science amp technology 1994 28 (4) 180-185

48 Gray N F Ozone disinfection In Microbiology of waterborne diseases ElsevierAcademic

Press 2014 pp 599-615

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in Ontario Canada Canadian biosystems engineering 2001 53 (6) 9-18

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effluent Water Research 1989 23 (8) 1017-1025

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Hong H Chang Suk Kim Antimicrobial effect of different concentrations of ozonate water in the

sanitation of water experimentally inoculated with Escherichia coli Preventive Veterinary Medicine

2017 41 (2) 84-87

52 Liberti L Notarnicola M Lopez A Advanced Treatment For Municipal Wastewater

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and aquaculture In World Health Organization Geneva 1989

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in orange juice using ozone Innovative Food Science amp Emerging Technologies 2009 10 (4) 551-

557

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Burgmann H von Gunten U Inactivation of Antibiotic Resistant Bacteria and Resistance Genes by

Ozone From Laboratory Experiments to Full-Scale Wastewater Treatment Environmental Science amp

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aqueous ozone Applied microbiology 2004 96 (5) 1133-42

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32 Activated sludge process

Shown in Figure 2 are the values for MLSS in the ASP (24 h HRT) presented as a function of

time which increase and reach a steady state at approximately 3300 mgL MLSS in about 40

days Comparable MLSS values were obtained in a similar study by Chen and Lo 17 setting the

best operational MLSS and SRT values at 3200 mgL and 994 days respectively Moreover the

MLSS and SRT values herein obtained also fall within the range of operational parameters for

ASP recommended by the United States Environmental Protection Agency 37

Also shown in Figure 2 is the MLVSS whose values also exhibit a similar increase and plateau

pattern as observed for the MLSS It is worthy to note the low values for the MLVSS and

MLVSSMLSS ratio with the latter ranging between 026 and 032 (24 h HRT) Such low values

indicate high content of inorganic matter in the raw wastewater and is attributed to a poor abattoir

pre-treatment ie poor coagulation and flocculation Lovett et al 38 and Paboacuten and Suaacuterez

Geacutelvez 14 indicated MLVSSMLSS ratios of 065 and 072-085 respectively and the higher ratio

in the latter was attributed to a better separation of inorganic compounds before entering a

biological treatment

Figure 2 MLSS and MLVSS progress as a function of time in the ASP as well as MLVSSMLSS ratio

33 A combined activated sludge-filtration-ozonation process

Once the steady state was established for the ASP the mixed liquor from the ASP was filtered

followed by ozonation The COD and BOD of the liquid at each treatment step are plotted in

Figure 3 It can be seen that the AFO process (24 h HRT ASP) reduced the COD and BOD levels

down to 128 plusmn 41 mgL and 12 plusmn 1 mgL respectively This corresponds to an average reduction

of 929 (COD) and 981 (BOD) relative to the raw wastewater In this AFO process the 17

min of ozonation worked as a polishing step to slightly reduce the COD level while not affecting

the final BOD value In this particular case carbon was reduced almost entirely during the

biological process resulting in a reduction of 901 (COD) and 974 (BOD) The filtration step

had no significant effect on COD and BOD Increasing ozonation time did not further reduce both

COD and BOD

The highest reduction in COD found in the literature was reported by Proesmans et al 33 where

they combined a biological-ozonation system to treat abattoir wastewater They reported a higher

reduction in COD by ozonation from 89 mgL (after biological treatment) to 30 mgL (after

ozonation) However in that study an ozone concentration of up to 200 mg O3L was used This

ozone dose is three times higher than the one used in the present study The dependence of the

applied ozone dose on the COD reduction is also stated by Tripathi et al 24

The reduction of the ASP HRT from 24 h to 12 h had a minimal effect on organic load removal

where similar COD values were observed for both HRTs (Figure 3) For the BOD values

decreasing the HRT increased the BOD from 17 mgL to 32 mgL This is attributed to the

bacteria having a shorter residence time in the ASP reactor for BOD reduction (such as hard BOD

or less readily biodegradable organic matter)39 40 Although minimal this led to a decrease in the

final reduction in the AFO process for BOD when the HRT was reduced from 24 h (98) to 12 h

(97)

Figure 3 Average COD and BOD values for every step of the AFO process at 24 h and 12 h ASP HRT with

17 min ozonation time

Research however has shown the potential of ozone in reducing COD and BOD by applying it to

abattoir wastewater without a previous biological treatment 11 31

Besides removing organic matter the AFO system also efficiently reduced TSS Figure 4 depicts

a final reduction of 988 after applying 17 min ozonation to the filtrate Such a reduction is

translated into a TSS average value of 3 plusmn 2 mgL agreeing with reported values elsewhere 28 41

905 of the reduction was measured after the ASP decreasing TSS value from 250 mgL (raw

effluent) to 238 mgL (mixed liquor)

Figure 4 TSS content for every step of the AFO process at 24h and 12h ASP HRT with 17 min ozonation

time

As observed with carbon filtration by 4-7 microm pore size filter paper did not reduce TSS and

neither did increasing ozone exposure time However from the experimental results obtained

during the preliminary phase (non-steady state for the ASP) a notable reduction in all the

measured parameters (COD BOD TSS and P) was obtained after filtration compared to those

before the filtration step During this non-steady state phase COD was reduced from 270 plusmn 15

mgL to 230 plusmn 10 mgL BOD from 31 plusmn 10 mgL to 15plusmn1 TSS from 30 plusmn 3 mgL to 16 plusmn 5 mgL

and P from 17 plusmn 5 mgL to 10 plusmn 5 mgL Therefore it could be underlined that filtration could

work as a backup process along with ozonation if the ASP fails

Analysing samples from the 12 h HRT in the ASP TSS reduction after the combined system falls

to 90 in comparison to that of 24 h HRT (988) with a final value of 22 mgL after the AFO

This value is notably higher than the value of 3 mgL for the 24 h HRT A similar explanation

used to address the different BOD results could be applied to the TSS That is in the 12 h HRT

ASP bacteria had less time to degrade the solids in the raw influent leading to a higher value in

the ASP effluent (24 mgL and 60 mgL after 24 h and 12 h HRT ASP respectively) Therefore

decreasing HRT could have adversely affected the solubilisation of colloidal and particulate

BOD resulting in the increase in the final TSS 42

P analyses show post ozonation values in the order of 19 plusmn 1 mgL (984 reduction) The ASP

reduced P values down to 195 plusmn 7 mgL (83) further lowering P values to 132 plusmn 9 mgL

(885) with filtration As observed with TSS increasing ozone contact time did not further

decrease P The change in ASP HRT did not make a significant difference either

In regards to pH raw wastewater samples had a pH of around 53 while the pH throughout the

AFO process ranged between 79 and 83 agreeing with already published data 28 41 43 pH

increase could be attributed to the formation of free ammonia during the ASP and its subsequent

reaction with CO2 produced during the aerobic process This results in ammonium bicarbonate

increasing alkalinity and generating a buffering capacity in the system 9

The total dissolved nitrogen content was also measured and found a reduction of 30 (from 224 plusmn

95 mgL for raw wastewater) after the ASP and maintained at a constant value of 160 plusmn 27 mgL

throughout the rest of the process Ammonia (NH4-N) reduction also happened mainly in the

bioreactor reducing NH4-N by 22 and reaching a constant value of 116 plusmn 12 mgL during

filtration and ozonation Finally nitrate was reduced by 85 during the biological step achieving

a value of 2 plusmn 1 mgL after the ASP The ASP was not design for nitrogen removal and therefore

the efficiency obtained in the AFO was lower than those found in the literature for nitrogen

reduction 19 36 38 44

331Microbial counts

During ozonation oxidation can occur through direct reaction involving molecular ozone and

via an indirect pathway through hydroxyl radicals (OH) formed during ozone decomposition

The former selectively attacks organic compounds while the latter hydroxyl radicals reacts

non-selectively with many dissolved compounds (organic and inorganic contaminants) and

the water matrix 20 45-48 By oxidation of the specific cell wall components ozone disinfects

water and kills bacteria 48

To assess disinfection efficiency samples were analysed for TC and TVC Prior to the

ozonation step the average values of TC and TVC in the filtrate were found to be 14times104

CFU100 ml and 46times109 CFU100 ml respectively Similar values were reported in the

literature 9 18 49

3311 Total Coliforms

In this study a complete inactivation of TC (4 log reduction) was achieved after dosing

the filtrate samples with ozone at 71 plusmn 17 mg O3L for 10 minutes (Figure 5) In the

literature 1 50 it is reported that up to 6 log of bacterial inactivation (Faecal Coliforms TC

and E coli mainly) were achieved after having ozonised industrial or municipal

wastewater Additionally Figure 5 shows that within the first two minutes of ozonation

the number of TC remained constant This behaviour is attributed to the presence of a

high amount of organic matter as Arayan et al 51 reported They found no bacterial

inactivation in the first minute of ozone exposure time when using 001 and 0001

fetal bovine serum (FBS) as organic matter However when the FBS concentration was

decreased to 00001 bacterial inactivation was observed within the first minute of

ozonation In the same way Liberti et al 52 showed a sudden bacterial disinfection within

the first 01 minute with a total dissolved organic carbon value of 7 mgL which is much

lower in comparison to the carbon values reported in this study Xu et al30 also reported

the importance of organic matter on ozone demand and inactivation time

Neither filtration nor ASP HRT reduction significantly affected the final disinfection

efficiency (a complete inactivation of TC was achieved with and without filtration for

both 12 h and 24 h ASP HRT after applying ozone for 10 min)

Figure 5 TC progress as a function of ozonation exposure

The World Health Organisation (WHO) recommends less than 1000 geometric mean

number of faecal coliforms per 100 ml for unrestricted irrigation for edible crops sports

fields and public parks 53 When it comes to drinking water standards the maximum

acceptable concentration of TC is zero per 100 ml noting that for water put into bottles or

containers the limit is set at zero per 250 ml 54 Both limits were met after an ozone

contact time of 10 minutes in the AFO system

3312 Total Viable Counts

On the contrary ozone could not completely remove TVC even after increasing the

ozone exposure time up to 1 hour as seen in Figure 6 However 6 log of inactivation was

obtained when subjecting the filtrate to 30 min of ozonation The average TVC after

ozonation was 6times103 CFU100 ml Increasing ozone contact time to 1 hour did not further

inactivate TVC In references 25 30 52 similar observations were made where there were no

further changes in the FC inactivation when the ozone exposure time was increased from

2 to 10 min and from 5 to 15 min In references 55 56 increasing ozonation time from 10 to

40 min did not result in further bacterial reduction

Figure 6 TVC progress as a function of ozonation exposure

The few TVC that remained alive after 30 min of ozone exposure could be resistant to

ozone These TVC could have developed defence mechanisms against ozone and be

resistant to its oxidation 57 58[52] producing ozone resistant coatings 59 or the formation of

ozone resistant pigments and biofilms 56 Microbes could also have remained within the

suspended solids left in wastewater where the solids acted as a barrier against ozone

oxidation 55 57 The setup of the ozonation chamber may have also played a role in the

mixing and transfer efficiency of ozone in wastewater 60 resulting in a lower TVC

removal It is important to mention that after 30 min contact time with ozone all the TVC

values in the wastewater were below the drinking water limit set by the European

Commission at 100 CFUml 54

Filtration had negligible effect on TC and TVC contrary to what was reported by Liberti

et al 52 According to their report 1 log difference on bacterial inactivation was achieved

between clarified and clarified-filtered feeds when using a multilayer pressure filter (deep

bed sand filter) filled with high purity silica sand and gravel The difference between the

results could be explain by the better solid removal efficiency of the deep bed sand filter

compared to the filter paper used in the present study as well as the applied ozone dose

Liberti et al 52 used an ozone dose between 7 and 15 mg O3L while in this study a much

higher ozone dose was applied (71 mg O3L) Such a high ozone dose could have led to

the inactivation of almost all the microorganisms (lt100 CFUml) regardless the amount

of TSS before ozonation Thus comparing the amount of TSS between the 24 h ASP

HRT (24 mgL) and 12 h ASP HRT (60 mgL) no difference in the final TVC was

measured after ozonating both feeds At the same time Venosa et al 60 concluded that

filtration improves substantially coliform (total and faecal) inactivation if secondary

effluent is of poor quality while not being necessary effluent filtration before ozonation if

total COD values are already low enough In this study a negligible difference in COD

was measured between filtered (178 mgL) and non-filtered (179 mgL) feeds agreeing

with the conclusion drawn by Venosa et al 60

34 Process analysis and assessment

In the combined AFO system filtration had no significant effect on organic matter and TSS

removal while ozonation worked as a polishing step on the reduction of COD BOD and TSS

Filtration however showed the potential to reduce the aforementioned parameters for the non-

steady state ASP effluent and therefore it could work as a backup process along with ozone if

the ASP fails At the same time the ASP HRT could be further reduced with a minimal effect on

substrate (BOD) removal efficiency increasing the overall efficiency of the process

On the other hand ozone was highly effective in microorganisms inactivation reducing TC and

TVC values below drinking water standards 54 Neither filtration nor ASP HRT reduction made a

significant difference in the final disinfection efficiency considering the high disinfection

potential of ozone and the applied dose

Based on the results presented in the study and considering the possible improvements for the

ASP (eg SRT and HRT adjustment nitrogen reduction etc) and the ozonation chamber (eg

increase ozone transfer efficiency) it is reasonable to say that the combined AFO system has the

potential to reach water reuse levels or even meet drinking water standards when treating abattoir

wastewater

4 Conclusions

The experimental results obtained in the AFO system proved the process is effective in reducing

organic load as well as TSS P and microbial content

COD and BOD reduction by 93 (128 mgL) and 98 (12 mgL) respectively

TSS and P reduction by 99 (3 mgL) and 98 (19 mgL) respectively

A complete inactivation (100) of TC after 10 min of ozonation

6 log reduction of TVC after 30 min of ozonation

Additionally no appreciable difference was observed between filtered and non-filtered systems

once the ASP reached the steady state For the two ASP HRTs under investigation 24 h and 12 h

and excluding TSS values no difference was found Increasing ozonation exposure from 30

minutes to 1 hour did not improve the overall efficiency of the process

Overall the combined process was sufficient to meet discharge requirements without further

treatment for the measured parameters (COD BOD TSS P TC and TVC)

Acknowledgements

We thank Worldwide Industries Pte Ltd for financial support We also acknowledge Mr C Burt and

Mr B Gibbons for their help as well as Dr D Herrera for his comments and feedback

References

1 Janex M L Xu P Savoye P Laine J M Lazarova V In Ozonation as a wastewater

disinfection process to meet reuse regulations Proceedings of the ozone world congress 1999

International ozone association 1999 pp 81-92

2 Council Directive 91271EEC concerning urban waste-water treatment L 30 European

Commission In 1991 pp 40-52

3 Amec Foster Wheeler Environment amp Infrastructure UK Ltd I ACTeon IMDEA and

NTUA EU-level instruments on water reuse European Comission In Publications Office of the

European Union Luxembourg 2016

4 Gerbens-Leenes P W Mekonnen M M Hoekstra A Y The water footprint of poultry

pork and beef A comparative study in different countries and production systems Water Resources

and Industry 2013 1-2 25-36

5 Rami Z Water and energy use and wastewater production in a beef packing plant MSc

thesis University of Nebraska-Lincoln 2015

6 Mekonnen M M Hoekstra A Y The green blue and grey water footprint of crops and

derived crop products UNESCO-IHE Delft The Netherlands Value of Water Research Report

Series 2010

7 Mekonnen M M Hoekstra A Y A global assessment of the water fooprint of farm animal

products Ecosystems 2012 15 401-415

8 Arvanitoyannis I S Ladas D Meat waste treatment methods and potential uses

International Journal of Food Science amp Technology 2008 43 (3) 543-559

9 Padilla-Gasca E Lopez-Lopez A Gallardo-Valdez J Evaluation of Stability Factors in

the Anaerobic Treatment of Slaughterhouse Wastewater Journal of Bioremediation amp

Biodegradation 2011 02 (01)

10 Bustillo-Lecompte C F Mehrvar M Treatment of an actual slaughterhouse wastewater by

integration of biological and advanced oxidation processes Modeling optimization and cost-

effectiveness analysis Journal of Environmental Management 2016 182 651-66

11 Wu J Doan H Disinfection of recycled red-meat-processing wastewater by ozone Journal

of Chemical Technology amp Biotechnology 2005 80 (7) 828-833

12 Travers S M Lovett D A Activated sludge treatment of abattoir wastewater-II Influence

of dissolved oxygen concentration Water research 1984 18 (4) 435-439

13 Al-Mutairi N Z Al-Sharifi F A Al-Shammari S B Evaluation study of a slaughterhouse

wastewater treatment plant including contact-assisted activated sludge and DAF Desalination 2008

225 (1-3) 167-175

14 Paboacuten S L Suaacuterez Geacutelvez J H Starting-up operating a full-scale activated sludge system

for slaughterhouse wastewater Revista Ingenieriacutea e Investigacioacuten 2009 29 (2) 53-58

15 Johns M R Developments in wastewater treatment in the meat processing industry a

review Bioresource technology 1995 54 (3) 203-216

16 Hsiao T H Huang J S Huang Y I Process kinetics of an activated-sludge reactor

system treating poultry slaughterhouse wastewater Environ Technol 2012 33 (7-9) 829-35

17 Chen C K Lo S L Treatment of slaughterhouse wastewater using an activated

sludgecontact aeration process Water Science amp Technology 2003 47 (12) 285-292

18 Um M M Barraud O Kerouredan M Gaschet M Stalder T Oswald E Dagot C

Ploy M C Brugere H Bibbal D Comparison of the incidence of pathogenic and antibiotic-

resistant Escherichia coli strains in adult cattle and veal calf slaughterhouse effluents highlighted

different risks for public health Water Research 2016 88 30-8

19 Heddle J F Activated sludge treatment of slaughterhouse wastes with protein recovery

Water research 1979 13 581-584

20 Gehr R Wagner M Veerasubramanian P Payment P Disinfection efficiency of

peracetic acid UV and ozone after enhanced primary treatment of municipal wastewater Water

Research 2003 37 (19) 4573-4586

21 Gehr R Wright H UV disinfection of wastewater coagulated with ferric chloride

recalcitrance and fouling problems Water Science amp Technology 1998 38 (3) 15-23

22 Lazarova V Janex M L Fiksdal L Oberg C Barcina I Pommepuy M Advanced

wastewater disinfection technologies short and long term efficiency Water Science amp Technology

1998 38 (12) 109-117

23 Paraskeva P Graham N J D Treatment of a secondary municipal effluent by ozone UV

and microfiltration microbial reduction and effect on effluent quality Desalination 2005 186 (1-3)

47-56

24 Tripathi S Pathak V Tripathi D M Tripathi B D Application of ozone based

treatments of secondary effluents Bioresource Technology 2011 102 (3) 2481-6

25 Lazarova V Liechti P-A Savoye P Hausler R Ozone disinfection main parameters for

process design in wastewater treatment and reuse Journal of Water Reuse and Desalination 2013 3

(4) 337

26 Absi F Gamache F Gehr R Liechti P Nicell J Pilot plant investigation of ozone

disinfection of physico-chemically treatedmunicipal wastewater Ozone Water Wastewater Treatment

1993 1 (7) 33-42

27 Langlais B Legube B Beuffe H Dore M Study of the nature of the by-products formed

and the risks of toxicity when disinfecting a secondary effluent with ozone Water Science amp

Technology 1992 25 (12) 135-143

28 Nebel C Gottschling D Hutchinson R L McBride T J Taylor D M Pavoni J L

Tittlebaum M E Spencer H E Fleischman M Ozone disinfection of industrial municipal

secondary effluents Water pollution control federation 1974 45 (12) 2493-2507

29 Pavoni J L Tittlebaum M E Spencer H E Fleischman M Nebel C Gottschling D

Virus removal from wastewater using ozone Water and sewage works 1972 119 (12) 59-67

30 Xu P Janex M-L Savoye P Cockx A Lazarova V Wastewater disinfection by ozone

main parameters for process design Water Research 2002 36 (4) 1043-1055

31 Millamena O M Ozone treatment of slaughterhouse and laboratory wastewaters

Aquacultural Engineering 1991 11 23-31

32 Roux A Renovation of wastewater for direct re-use in an abattoir MSc thesis University of

Pretoria 1996

33 Proesmans P De Vil R Gerards R Vriends L Advanced treatment of industrial

wastewaters combination of biological treatment and ozonation Mededelingen-faculteit

landbouwkundige en toegepaste biologische wetenschappen 1997 62 (4) 1729-1736

34 APHA American Public Health Association Standard Methods for the Examination of

Water and Wastewater 20 ed Washington DC 1998

35 Al-Mutairi N Z Hamoda M F Al-Ghusain I A Performance-Based Characterization of

a Contact Stabilization Process for Slaughterhouse Wastewater Journal of Environmental Science

and Health Part A 2003 38 (10) 2287-2300

36 Fongsatitkul P Wareham D G Elefsiniotis P Charoensuk P Treatment of a

slaughterhouse wastewater effect of internal recycle rate on chemical oxygen demand total Kjeldahl

nitrogen and total phosphorus removal Environmental Technology 2011 32 (15) 1755-1759

37 Environmental Protection Agency Wastewater treatment manuals Primary secondary and

tertiary treatment Ardcavan Wexford Ireland 1997

38 Lovett D A Travers S M Davey K R Activated sludge treatment of abattoir

wastewater-I Influence of sludge age and feeding pattern Water Research 1984 18 (4) 429-434

39 Abbas H Seif H Moursy A Effect of hydraulic retention time on the activated sludge

system In Sixth International Water Technology Conference Alexandria Egypt 2001 pp 277-284

40 Zhang Y Wang X Hu M Li P Effect of hydraulic retention time (HRT) on the

biodegradation of trichloroethylene wastewater and anaerobic bacterial community in the UASB

reactor Applied microbiology biotechnology 2015 99 (4) 1977-87

41 Martiacutenez S B Peacuterez-Parra J Suay R Use of Ozone in Wastewater Treatment to Produce

Water Suitable for Irrigation Water Resources Management 2011 25 (9) 2109-2124

42 Gerardi M Settleability problems and loss of solids in the activated sludge process New

Jersey USA John Wiley and Sons 2002 179 p 2002

43 Paraskeva P Lambert S D Graham N J D Influence of Ozonation Conditions on the

Treatability of Secondary Effluents Ozone Science amp Engineering 1998 20 (2) 133-150

44 Bustillo-Lecompte C F Mehrvar M Quinones-Bolanos E Combined anaerobic-aerobic

and UVH2O2 processes for the treatment of synthetic slaughterhouse wastewater Environmental

Science and Health Part A Toxichazardous substances amp environmetal engineering 2013 48 (9)

1122-35

45 von Gunten U Ozonation of drinking water Part I Oxidation kinetics and product

formation Water Research 2003 37 (7) 1443-1467

46 Jin X Peldszus S Huck P M Reaction kinetics of selected micropollutants in ozonation

and advanced oxidation processes Water Research 2012 46 (19) 6519-30

47 Masten S J Davies S H R The use of ozonation to degrade organic contaminants in

wastewaters Environmental science amp technology 1994 28 (4) 180-185

48 Gray N F Ozone disinfection In Microbiology of waterborne diseases ElsevierAcademic

Press 2014 pp 599-615

49 Wu P F Mittal G S Characterization of provincial inspected slaughterhouse wastewater

in Ontario Canada Canadian biosystems engineering 2001 53 (6) 9-18

50 Finch G R Smith D W Ozone dose-response of Escherichia coli in activated sludge

effluent Water Research 1989 23 (8) 1017-1025

51 Arayan L Alisha W B Reyes Huynh T Hop Huy T Xuan Eun J Baek Han S Yang

Hong H Chang Suk Kim Antimicrobial effect of different concentrations of ozonate water in the

sanitation of water experimentally inoculated with Escherichia coli Preventive Veterinary Medicine

2017 41 (2) 84-87

52 Liberti L Notarnicola M Lopez A Advanced Treatment For Municipal Wastewater

Reuse In Agriculture III - Ozone Disinfection Ozone Science amp Engineering 2000 22 (2) 151-166

53 Mara D Cairncross S Guidelines for the safe use of wastewater and excreta in agriculture

and aquaculture In World Health Organization Geneva 1989

54 Council Directive 9883EC on the quality of water intended for human consumption O

European Union In 1998 p 42

55 Dietrich J P Loge F J Ginn T R Basagaoglu H Inactivation of particle-associated

microorganisms in wastewater disinfection modeling of ozone and chlorine reactive diffusive

transport in polydispersed suspensions Water Research 2007 41 (10) 2189-201

56 Hess S Gallert C Sensitivity of antibiotic resistant and antibiotic susceptible Escherichia

coli Enterococcus and Staphylococcus strains against ozone Water Health 2015 13 (4) 1020-8

57 Patil S Bourke P Frias J M Tiwari B K Cullen P J Inactivation of Escherichia coli

in orange juice using ozone Innovative Food Science amp Emerging Technologies 2009 10 (4) 551-

557

58 Czekalski N Imminger S Salhi E Veljkovic M Kleffel K Drissner D Hammes F

Burgmann H von Gunten U Inactivation of Antibiotic Resistant Bacteria and Resistance Genes by

Ozone From Laboratory Experiments to Full-Scale Wastewater Treatment Environmental Science amp

Technology 2016 50 (21) 11862-11871

59 Young S B Setlow P Mechanisms of Bacillus subtilis spore resistance to and killing by

aqueous ozone Applied microbiology 2004 96 (5) 1133-42

60 Venosa A D Meckes M C Opatken E J Disinfection of filtered and unfiltered

secondary effluent in two ozone contactors Environment International 1981 4 299-311

Once the steady state was established for the ASP the mixed liquor from the ASP was filtered

followed by ozonation The COD and BOD of the liquid at each treatment step are plotted in

Figure 3 It can be seen that the AFO process (24 h HRT ASP) reduced the COD and BOD levels

down to 128 plusmn 41 mgL and 12 plusmn 1 mgL respectively This corresponds to an average reduction

of 929 (COD) and 981 (BOD) relative to the raw wastewater In this AFO process the 17

min of ozonation worked as a polishing step to slightly reduce the COD level while not affecting

the final BOD value In this particular case carbon was reduced almost entirely during the

biological process resulting in a reduction of 901 (COD) and 974 (BOD) The filtration step

had no significant effect on COD and BOD Increasing ozonation time did not further reduce both

COD and BOD

The highest reduction in COD found in the literature was reported by Proesmans et al 33 where

they combined a biological-ozonation system to treat abattoir wastewater They reported a higher

reduction in COD by ozonation from 89 mgL (after biological treatment) to 30 mgL (after

ozonation) However in that study an ozone concentration of up to 200 mg O3L was used This

ozone dose is three times higher than the one used in the present study The dependence of the

applied ozone dose on the COD reduction is also stated by Tripathi et al 24

The reduction of the ASP HRT from 24 h to 12 h had a minimal effect on organic load removal

where similar COD values were observed for both HRTs (Figure 3) For the BOD values

decreasing the HRT increased the BOD from 17 mgL to 32 mgL This is attributed to the

bacteria having a shorter residence time in the ASP reactor for BOD reduction (such as hard BOD

or less readily biodegradable organic matter)39 40 Although minimal this led to a decrease in the

final reduction in the AFO process for BOD when the HRT was reduced from 24 h (98) to 12 h

(97)

Figure 3 Average COD and BOD values for every step of the AFO process at 24 h and 12 h ASP HRT with

17 min ozonation time

Research however has shown the potential of ozone in reducing COD and BOD by applying it to

abattoir wastewater without a previous biological treatment 11 31

Besides removing organic matter the AFO system also efficiently reduced TSS Figure 4 depicts

a final reduction of 988 after applying 17 min ozonation to the filtrate Such a reduction is

translated into a TSS average value of 3 plusmn 2 mgL agreeing with reported values elsewhere 28 41

905 of the reduction was measured after the ASP decreasing TSS value from 250 mgL (raw

effluent) to 238 mgL (mixed liquor)

Figure 4 TSS content for every step of the AFO process at 24h and 12h ASP HRT with 17 min ozonation

time

As observed with carbon filtration by 4-7 microm pore size filter paper did not reduce TSS and

neither did increasing ozone exposure time However from the experimental results obtained

during the preliminary phase (non-steady state for the ASP) a notable reduction in all the

measured parameters (COD BOD TSS and P) was obtained after filtration compared to those

before the filtration step During this non-steady state phase COD was reduced from 270 plusmn 15

mgL to 230 plusmn 10 mgL BOD from 31 plusmn 10 mgL to 15plusmn1 TSS from 30 plusmn 3 mgL to 16 plusmn 5 mgL

and P from 17 plusmn 5 mgL to 10 plusmn 5 mgL Therefore it could be underlined that filtration could

work as a backup process along with ozonation if the ASP fails

Analysing samples from the 12 h HRT in the ASP TSS reduction after the combined system falls

to 90 in comparison to that of 24 h HRT (988) with a final value of 22 mgL after the AFO

This value is notably higher than the value of 3 mgL for the 24 h HRT A similar explanation

used to address the different BOD results could be applied to the TSS That is in the 12 h HRT

ASP bacteria had less time to degrade the solids in the raw influent leading to a higher value in

the ASP effluent (24 mgL and 60 mgL after 24 h and 12 h HRT ASP respectively) Therefore

decreasing HRT could have adversely affected the solubilisation of colloidal and particulate

BOD resulting in the increase in the final TSS 42

P analyses show post ozonation values in the order of 19 plusmn 1 mgL (984 reduction) The ASP

reduced P values down to 195 plusmn 7 mgL (83) further lowering P values to 132 plusmn 9 mgL

(885) with filtration As observed with TSS increasing ozone contact time did not further

decrease P The change in ASP HRT did not make a significant difference either

In regards to pH raw wastewater samples had a pH of around 53 while the pH throughout the

AFO process ranged between 79 and 83 agreeing with already published data 28 41 43 pH

increase could be attributed to the formation of free ammonia during the ASP and its subsequent

reaction with CO2 produced during the aerobic process This results in ammonium bicarbonate

increasing alkalinity and generating a buffering capacity in the system 9

The total dissolved nitrogen content was also measured and found a reduction of 30 (from 224 plusmn

95 mgL for raw wastewater) after the ASP and maintained at a constant value of 160 plusmn 27 mgL

throughout the rest of the process Ammonia (NH4-N) reduction also happened mainly in the

bioreactor reducing NH4-N by 22 and reaching a constant value of 116 plusmn 12 mgL during

filtration and ozonation Finally nitrate was reduced by 85 during the biological step achieving

a value of 2 plusmn 1 mgL after the ASP The ASP was not design for nitrogen removal and therefore

the efficiency obtained in the AFO was lower than those found in the literature for nitrogen

reduction 19 36 38 44

331Microbial counts

During ozonation oxidation can occur through direct reaction involving molecular ozone and

via an indirect pathway through hydroxyl radicals (OH) formed during ozone decomposition

The former selectively attacks organic compounds while the latter hydroxyl radicals reacts

non-selectively with many dissolved compounds (organic and inorganic contaminants) and

the water matrix 20 45-48 By oxidation of the specific cell wall components ozone disinfects

water and kills bacteria 48

To assess disinfection efficiency samples were analysed for TC and TVC Prior to the

ozonation step the average values of TC and TVC in the filtrate were found to be 14times104

CFU100 ml and 46times109 CFU100 ml respectively Similar values were reported in the

literature 9 18 49

3311 Total Coliforms

In this study a complete inactivation of TC (4 log reduction) was achieved after dosing

the filtrate samples with ozone at 71 plusmn 17 mg O3L for 10 minutes (Figure 5) In the

literature 1 50 it is reported that up to 6 log of bacterial inactivation (Faecal Coliforms TC

and E coli mainly) were achieved after having ozonised industrial or municipal

wastewater Additionally Figure 5 shows that within the first two minutes of ozonation

the number of TC remained constant This behaviour is attributed to the presence of a

high amount of organic matter as Arayan et al 51 reported They found no bacterial

inactivation in the first minute of ozone exposure time when using 001 and 0001

fetal bovine serum (FBS) as organic matter However when the FBS concentration was

decreased to 00001 bacterial inactivation was observed within the first minute of

ozonation In the same way Liberti et al 52 showed a sudden bacterial disinfection within

the first 01 minute with a total dissolved organic carbon value of 7 mgL which is much

lower in comparison to the carbon values reported in this study Xu et al30 also reported

the importance of organic matter on ozone demand and inactivation time

Neither filtration nor ASP HRT reduction significantly affected the final disinfection

efficiency (a complete inactivation of TC was achieved with and without filtration for

both 12 h and 24 h ASP HRT after applying ozone for 10 min)

Figure 5 TC progress as a function of ozonation exposure

The World Health Organisation (WHO) recommends less than 1000 geometric mean

number of faecal coliforms per 100 ml for unrestricted irrigation for edible crops sports

fields and public parks 53 When it comes to drinking water standards the maximum

acceptable concentration of TC is zero per 100 ml noting that for water put into bottles or

containers the limit is set at zero per 250 ml 54 Both limits were met after an ozone

contact time of 10 minutes in the AFO system

3312 Total Viable Counts

On the contrary ozone could not completely remove TVC even after increasing the

ozone exposure time up to 1 hour as seen in Figure 6 However 6 log of inactivation was

obtained when subjecting the filtrate to 30 min of ozonation The average TVC after

ozonation was 6times103 CFU100 ml Increasing ozone contact time to 1 hour did not further

inactivate TVC In references 25 30 52 similar observations were made where there were no

further changes in the FC inactivation when the ozone exposure time was increased from

2 to 10 min and from 5 to 15 min In references 55 56 increasing ozonation time from 10 to

40 min did not result in further bacterial reduction

Figure 6 TVC progress as a function of ozonation exposure

The few TVC that remained alive after 30 min of ozone exposure could be resistant to

ozone These TVC could have developed defence mechanisms against ozone and be

resistant to its oxidation 57 58[52] producing ozone resistant coatings 59 or the formation of

ozone resistant pigments and biofilms 56 Microbes could also have remained within the

suspended solids left in wastewater where the solids acted as a barrier against ozone

oxidation 55 57 The setup of the ozonation chamber may have also played a role in the

mixing and transfer efficiency of ozone in wastewater 60 resulting in a lower TVC

removal It is important to mention that after 30 min contact time with ozone all the TVC

values in the wastewater were below the drinking water limit set by the European

Commission at 100 CFUml 54

Filtration had negligible effect on TC and TVC contrary to what was reported by Liberti

et al 52 According to their report 1 log difference on bacterial inactivation was achieved

between clarified and clarified-filtered feeds when using a multilayer pressure filter (deep

bed sand filter) filled with high purity silica sand and gravel The difference between the

results could be explain by the better solid removal efficiency of the deep bed sand filter

compared to the filter paper used in the present study as well as the applied ozone dose

Liberti et al 52 used an ozone dose between 7 and 15 mg O3L while in this study a much

higher ozone dose was applied (71 mg O3L) Such a high ozone dose could have led to

the inactivation of almost all the microorganisms (lt100 CFUml) regardless the amount

of TSS before ozonation Thus comparing the amount of TSS between the 24 h ASP

HRT (24 mgL) and 12 h ASP HRT (60 mgL) no difference in the final TVC was

measured after ozonating both feeds At the same time Venosa et al 60 concluded that

filtration improves substantially coliform (total and faecal) inactivation if secondary

effluent is of poor quality while not being necessary effluent filtration before ozonation if

total COD values are already low enough In this study a negligible difference in COD

was measured between filtered (178 mgL) and non-filtered (179 mgL) feeds agreeing

with the conclusion drawn by Venosa et al 60

34 Process analysis and assessment

In the combined AFO system filtration had no significant effect on organic matter and TSS

removal while ozonation worked as a polishing step on the reduction of COD BOD and TSS

Filtration however showed the potential to reduce the aforementioned parameters for the non-

steady state ASP effluent and therefore it could work as a backup process along with ozone if

the ASP fails At the same time the ASP HRT could be further reduced with a minimal effect on

substrate (BOD) removal efficiency increasing the overall efficiency of the process

On the other hand ozone was highly effective in microorganisms inactivation reducing TC and

TVC values below drinking water standards 54 Neither filtration nor ASP HRT reduction made a

significant difference in the final disinfection efficiency considering the high disinfection

potential of ozone and the applied dose

Based on the results presented in the study and considering the possible improvements for the

ASP (eg SRT and HRT adjustment nitrogen reduction etc) and the ozonation chamber (eg

increase ozone transfer efficiency) it is reasonable to say that the combined AFO system has the

potential to reach water reuse levels or even meet drinking water standards when treating abattoir

wastewater

4 Conclusions

The experimental results obtained in the AFO system proved the process is effective in reducing

organic load as well as TSS P and microbial content

COD and BOD reduction by 93 (128 mgL) and 98 (12 mgL) respectively

TSS and P reduction by 99 (3 mgL) and 98 (19 mgL) respectively

A complete inactivation (100) of TC after 10 min of ozonation

6 log reduction of TVC after 30 min of ozonation

Additionally no appreciable difference was observed between filtered and non-filtered systems

once the ASP reached the steady state For the two ASP HRTs under investigation 24 h and 12 h

and excluding TSS values no difference was found Increasing ozonation exposure from 30

minutes to 1 hour did not improve the overall efficiency of the process

Overall the combined process was sufficient to meet discharge requirements without further

treatment for the measured parameters (COD BOD TSS P TC and TVC)

Acknowledgements

We thank Worldwide Industries Pte Ltd for financial support We also acknowledge Mr C Burt and

Mr B Gibbons for their help as well as Dr D Herrera for his comments and feedback

References

1 Janex M L Xu P Savoye P Laine J M Lazarova V In Ozonation as a wastewater

disinfection process to meet reuse regulations Proceedings of the ozone world congress 1999

International ozone association 1999 pp 81-92

2 Council Directive 91271EEC concerning urban waste-water treatment L 30 European

Commission In 1991 pp 40-52

3 Amec Foster Wheeler Environment amp Infrastructure UK Ltd I ACTeon IMDEA and

NTUA EU-level instruments on water reuse European Comission In Publications Office of the

European Union Luxembourg 2016

4 Gerbens-Leenes P W Mekonnen M M Hoekstra A Y The water footprint of poultry

pork and beef A comparative study in different countries and production systems Water Resources

and Industry 2013 1-2 25-36

5 Rami Z Water and energy use and wastewater production in a beef packing plant MSc

thesis University of Nebraska-Lincoln 2015

6 Mekonnen M M Hoekstra A Y The green blue and grey water footprint of crops and

derived crop products UNESCO-IHE Delft The Netherlands Value of Water Research Report

Series 2010

7 Mekonnen M M Hoekstra A Y A global assessment of the water fooprint of farm animal

products Ecosystems 2012 15 401-415

8 Arvanitoyannis I S Ladas D Meat waste treatment methods and potential uses

International Journal of Food Science amp Technology 2008 43 (3) 543-559

9 Padilla-Gasca E Lopez-Lopez A Gallardo-Valdez J Evaluation of Stability Factors in

the Anaerobic Treatment of Slaughterhouse Wastewater Journal of Bioremediation amp

Biodegradation 2011 02 (01)

10 Bustillo-Lecompte C F Mehrvar M Treatment of an actual slaughterhouse wastewater by

integration of biological and advanced oxidation processes Modeling optimization and cost-

effectiveness analysis Journal of Environmental Management 2016 182 651-66

11 Wu J Doan H Disinfection of recycled red-meat-processing wastewater by ozone Journal

of Chemical Technology amp Biotechnology 2005 80 (7) 828-833

12 Travers S M Lovett D A Activated sludge treatment of abattoir wastewater-II Influence

of dissolved oxygen concentration Water research 1984 18 (4) 435-439

13 Al-Mutairi N Z Al-Sharifi F A Al-Shammari S B Evaluation study of a slaughterhouse

wastewater treatment plant including contact-assisted activated sludge and DAF Desalination 2008

225 (1-3) 167-175

14 Paboacuten S L Suaacuterez Geacutelvez J H Starting-up operating a full-scale activated sludge system

for slaughterhouse wastewater Revista Ingenieriacutea e Investigacioacuten 2009 29 (2) 53-58

15 Johns M R Developments in wastewater treatment in the meat processing industry a

review Bioresource technology 1995 54 (3) 203-216

16 Hsiao T H Huang J S Huang Y I Process kinetics of an activated-sludge reactor

system treating poultry slaughterhouse wastewater Environ Technol 2012 33 (7-9) 829-35

17 Chen C K Lo S L Treatment of slaughterhouse wastewater using an activated

sludgecontact aeration process Water Science amp Technology 2003 47 (12) 285-292

18 Um M M Barraud O Kerouredan M Gaschet M Stalder T Oswald E Dagot C

Ploy M C Brugere H Bibbal D Comparison of the incidence of pathogenic and antibiotic-

resistant Escherichia coli strains in adult cattle and veal calf slaughterhouse effluents highlighted

different risks for public health Water Research 2016 88 30-8

19 Heddle J F Activated sludge treatment of slaughterhouse wastes with protein recovery

Water research 1979 13 581-584

20 Gehr R Wagner M Veerasubramanian P Payment P Disinfection efficiency of

peracetic acid UV and ozone after enhanced primary treatment of municipal wastewater Water

Research 2003 37 (19) 4573-4586

21 Gehr R Wright H UV disinfection of wastewater coagulated with ferric chloride

recalcitrance and fouling problems Water Science amp Technology 1998 38 (3) 15-23

22 Lazarova V Janex M L Fiksdal L Oberg C Barcina I Pommepuy M Advanced

wastewater disinfection technologies short and long term efficiency Water Science amp Technology

1998 38 (12) 109-117

23 Paraskeva P Graham N J D Treatment of a secondary municipal effluent by ozone UV

and microfiltration microbial reduction and effect on effluent quality Desalination 2005 186 (1-3)

47-56

24 Tripathi S Pathak V Tripathi D M Tripathi B D Application of ozone based

treatments of secondary effluents Bioresource Technology 2011 102 (3) 2481-6

25 Lazarova V Liechti P-A Savoye P Hausler R Ozone disinfection main parameters for

process design in wastewater treatment and reuse Journal of Water Reuse and Desalination 2013 3

(4) 337

26 Absi F Gamache F Gehr R Liechti P Nicell J Pilot plant investigation of ozone

disinfection of physico-chemically treatedmunicipal wastewater Ozone Water Wastewater Treatment

1993 1 (7) 33-42

27 Langlais B Legube B Beuffe H Dore M Study of the nature of the by-products formed

and the risks of toxicity when disinfecting a secondary effluent with ozone Water Science amp

Technology 1992 25 (12) 135-143

28 Nebel C Gottschling D Hutchinson R L McBride T J Taylor D M Pavoni J L

Tittlebaum M E Spencer H E Fleischman M Ozone disinfection of industrial municipal

secondary effluents Water pollution control federation 1974 45 (12) 2493-2507

29 Pavoni J L Tittlebaum M E Spencer H E Fleischman M Nebel C Gottschling D

Virus removal from wastewater using ozone Water and sewage works 1972 119 (12) 59-67

30 Xu P Janex M-L Savoye P Cockx A Lazarova V Wastewater disinfection by ozone

main parameters for process design Water Research 2002 36 (4) 1043-1055

31 Millamena O M Ozone treatment of slaughterhouse and laboratory wastewaters

Aquacultural Engineering 1991 11 23-31

32 Roux A Renovation of wastewater for direct re-use in an abattoir MSc thesis University of

Pretoria 1996

33 Proesmans P De Vil R Gerards R Vriends L Advanced treatment of industrial

wastewaters combination of biological treatment and ozonation Mededelingen-faculteit

landbouwkundige en toegepaste biologische wetenschappen 1997 62 (4) 1729-1736

34 APHA American Public Health Association Standard Methods for the Examination of

Water and Wastewater 20 ed Washington DC 1998

35 Al-Mutairi N Z Hamoda M F Al-Ghusain I A Performance-Based Characterization of

a Contact Stabilization Process for Slaughterhouse Wastewater Journal of Environmental Science

and Health Part A 2003 38 (10) 2287-2300

36 Fongsatitkul P Wareham D G Elefsiniotis P Charoensuk P Treatment of a

slaughterhouse wastewater effect of internal recycle rate on chemical oxygen demand total Kjeldahl

nitrogen and total phosphorus removal Environmental Technology 2011 32 (15) 1755-1759

37 Environmental Protection Agency Wastewater treatment manuals Primary secondary and

tertiary treatment Ardcavan Wexford Ireland 1997

38 Lovett D A Travers S M Davey K R Activated sludge treatment of abattoir

wastewater-I Influence of sludge age and feeding pattern Water Research 1984 18 (4) 429-434

39 Abbas H Seif H Moursy A Effect of hydraulic retention time on the activated sludge

system In Sixth International Water Technology Conference Alexandria Egypt 2001 pp 277-284

40 Zhang Y Wang X Hu M Li P Effect of hydraulic retention time (HRT) on the

biodegradation of trichloroethylene wastewater and anaerobic bacterial community in the UASB

reactor Applied microbiology biotechnology 2015 99 (4) 1977-87

41 Martiacutenez S B Peacuterez-Parra J Suay R Use of Ozone in Wastewater Treatment to Produce

Water Suitable for Irrigation Water Resources Management 2011 25 (9) 2109-2124

42 Gerardi M Settleability problems and loss of solids in the activated sludge process New

Jersey USA John Wiley and Sons 2002 179 p 2002

43 Paraskeva P Lambert S D Graham N J D Influence of Ozonation Conditions on the

Treatability of Secondary Effluents Ozone Science amp Engineering 1998 20 (2) 133-150

44 Bustillo-Lecompte C F Mehrvar M Quinones-Bolanos E Combined anaerobic-aerobic

and UVH2O2 processes for the treatment of synthetic slaughterhouse wastewater Environmental

Science and Health Part A Toxichazardous substances amp environmetal engineering 2013 48 (9)

1122-35

45 von Gunten U Ozonation of drinking water Part I Oxidation kinetics and product

formation Water Research 2003 37 (7) 1443-1467

46 Jin X Peldszus S Huck P M Reaction kinetics of selected micropollutants in ozonation

and advanced oxidation processes Water Research 2012 46 (19) 6519-30

47 Masten S J Davies S H R The use of ozonation to degrade organic contaminants in

wastewaters Environmental science amp technology 1994 28 (4) 180-185

48 Gray N F Ozone disinfection In Microbiology of waterborne diseases ElsevierAcademic

Press 2014 pp 599-615

49 Wu P F Mittal G S Characterization of provincial inspected slaughterhouse wastewater

in Ontario Canada Canadian biosystems engineering 2001 53 (6) 9-18

50 Finch G R Smith D W Ozone dose-response of Escherichia coli in activated sludge

effluent Water Research 1989 23 (8) 1017-1025

51 Arayan L Alisha W B Reyes Huynh T Hop Huy T Xuan Eun J Baek Han S Yang

Hong H Chang Suk Kim Antimicrobial effect of different concentrations of ozonate water in the

sanitation of water experimentally inoculated with Escherichia coli Preventive Veterinary Medicine

2017 41 (2) 84-87

52 Liberti L Notarnicola M Lopez A Advanced Treatment For Municipal Wastewater

Reuse In Agriculture III - Ozone Disinfection Ozone Science amp Engineering 2000 22 (2) 151-166

53 Mara D Cairncross S Guidelines for the safe use of wastewater and excreta in agriculture

and aquaculture In World Health Organization Geneva 1989

54 Council Directive 9883EC on the quality of water intended for human consumption O

European Union In 1998 p 42

55 Dietrich J P Loge F J Ginn T R Basagaoglu H Inactivation of particle-associated

microorganisms in wastewater disinfection modeling of ozone and chlorine reactive diffusive

transport in polydispersed suspensions Water Research 2007 41 (10) 2189-201

56 Hess S Gallert C Sensitivity of antibiotic resistant and antibiotic susceptible Escherichia

coli Enterococcus and Staphylococcus strains against ozone Water Health 2015 13 (4) 1020-8

57 Patil S Bourke P Frias J M Tiwari B K Cullen P J Inactivation of Escherichia coli

in orange juice using ozone Innovative Food Science amp Emerging Technologies 2009 10 (4) 551-

557

58 Czekalski N Imminger S Salhi E Veljkovic M Kleffel K Drissner D Hammes F

Burgmann H von Gunten U Inactivation of Antibiotic Resistant Bacteria and Resistance Genes by

Ozone From Laboratory Experiments to Full-Scale Wastewater Treatment Environmental Science amp

Technology 2016 50 (21) 11862-11871

59 Young S B Setlow P Mechanisms of Bacillus subtilis spore resistance to and killing by

aqueous ozone Applied microbiology 2004 96 (5) 1133-42

60 Venosa A D Meckes M C Opatken E J Disinfection of filtered and unfiltered

secondary effluent in two ozone contactors Environment International 1981 4 299-311

Figure 3 Average COD and BOD values for every step of the AFO process at 24 h and 12 h ASP HRT with

17 min ozonation time

Research however has shown the potential of ozone in reducing COD and BOD by applying it to

abattoir wastewater without a previous biological treatment 11 31

Besides removing organic matter the AFO system also efficiently reduced TSS Figure 4 depicts

a final reduction of 988 after applying 17 min ozonation to the filtrate Such a reduction is

translated into a TSS average value of 3 plusmn 2 mgL agreeing with reported values elsewhere 28 41

905 of the reduction was measured after the ASP decreasing TSS value from 250 mgL (raw

effluent) to 238 mgL (mixed liquor)

Figure 4 TSS content for every step of the AFO process at 24h and 12h ASP HRT with 17 min ozonation

time

As observed with carbon filtration by 4-7 microm pore size filter paper did not reduce TSS and

neither did increasing ozone exposure time However from the experimental results obtained

during the preliminary phase (non-steady state for the ASP) a notable reduction in all the

measured parameters (COD BOD TSS and P) was obtained after filtration compared to those

before the filtration step During this non-steady state phase COD was reduced from 270 plusmn 15

mgL to 230 plusmn 10 mgL BOD from 31 plusmn 10 mgL to 15plusmn1 TSS from 30 plusmn 3 mgL to 16 plusmn 5 mgL

and P from 17 plusmn 5 mgL to 10 plusmn 5 mgL Therefore it could be underlined that filtration could

work as a backup process along with ozonation if the ASP fails

Analysing samples from the 12 h HRT in the ASP TSS reduction after the combined system falls

to 90 in comparison to that of 24 h HRT (988) with a final value of 22 mgL after the AFO

This value is notably higher than the value of 3 mgL for the 24 h HRT A similar explanation

used to address the different BOD results could be applied to the TSS That is in the 12 h HRT

ASP bacteria had less time to degrade the solids in the raw influent leading to a higher value in

the ASP effluent (24 mgL and 60 mgL after 24 h and 12 h HRT ASP respectively) Therefore

decreasing HRT could have adversely affected the solubilisation of colloidal and particulate

BOD resulting in the increase in the final TSS 42

P analyses show post ozonation values in the order of 19 plusmn 1 mgL (984 reduction) The ASP

reduced P values down to 195 plusmn 7 mgL (83) further lowering P values to 132 plusmn 9 mgL

(885) with filtration As observed with TSS increasing ozone contact time did not further

decrease P The change in ASP HRT did not make a significant difference either

In regards to pH raw wastewater samples had a pH of around 53 while the pH throughout the

AFO process ranged between 79 and 83 agreeing with already published data 28 41 43 pH

increase could be attributed to the formation of free ammonia during the ASP and its subsequent

reaction with CO2 produced during the aerobic process This results in ammonium bicarbonate

increasing alkalinity and generating a buffering capacity in the system 9

The total dissolved nitrogen content was also measured and found a reduction of 30 (from 224 plusmn

95 mgL for raw wastewater) after the ASP and maintained at a constant value of 160 plusmn 27 mgL

throughout the rest of the process Ammonia (NH4-N) reduction also happened mainly in the

bioreactor reducing NH4-N by 22 and reaching a constant value of 116 plusmn 12 mgL during

filtration and ozonation Finally nitrate was reduced by 85 during the biological step achieving

a value of 2 plusmn 1 mgL after the ASP The ASP was not design for nitrogen removal and therefore

the efficiency obtained in the AFO was lower than those found in the literature for nitrogen

reduction 19 36 38 44

331Microbial counts

During ozonation oxidation can occur through direct reaction involving molecular ozone and

via an indirect pathway through hydroxyl radicals (OH) formed during ozone decomposition

The former selectively attacks organic compounds while the latter hydroxyl radicals reacts

non-selectively with many dissolved compounds (organic and inorganic contaminants) and

the water matrix 20 45-48 By oxidation of the specific cell wall components ozone disinfects

water and kills bacteria 48

To assess disinfection efficiency samples were analysed for TC and TVC Prior to the

ozonation step the average values of TC and TVC in the filtrate were found to be 14times104

CFU100 ml and 46times109 CFU100 ml respectively Similar values were reported in the

literature 9 18 49

3311 Total Coliforms

In this study a complete inactivation of TC (4 log reduction) was achieved after dosing

the filtrate samples with ozone at 71 plusmn 17 mg O3L for 10 minutes (Figure 5) In the

literature 1 50 it is reported that up to 6 log of bacterial inactivation (Faecal Coliforms TC

and E coli mainly) were achieved after having ozonised industrial or municipal

wastewater Additionally Figure 5 shows that within the first two minutes of ozonation

the number of TC remained constant This behaviour is attributed to the presence of a

high amount of organic matter as Arayan et al 51 reported They found no bacterial

inactivation in the first minute of ozone exposure time when using 001 and 0001

fetal bovine serum (FBS) as organic matter However when the FBS concentration was

decreased to 00001 bacterial inactivation was observed within the first minute of

ozonation In the same way Liberti et al 52 showed a sudden bacterial disinfection within

the first 01 minute with a total dissolved organic carbon value of 7 mgL which is much

lower in comparison to the carbon values reported in this study Xu et al30 also reported

the importance of organic matter on ozone demand and inactivation time

Neither filtration nor ASP HRT reduction significantly affected the final disinfection

efficiency (a complete inactivation of TC was achieved with and without filtration for

both 12 h and 24 h ASP HRT after applying ozone for 10 min)

Figure 5 TC progress as a function of ozonation exposure

The World Health Organisation (WHO) recommends less than 1000 geometric mean

number of faecal coliforms per 100 ml for unrestricted irrigation for edible crops sports

fields and public parks 53 When it comes to drinking water standards the maximum

acceptable concentration of TC is zero per 100 ml noting that for water put into bottles or

containers the limit is set at zero per 250 ml 54 Both limits were met after an ozone

contact time of 10 minutes in the AFO system

3312 Total Viable Counts

On the contrary ozone could not completely remove TVC even after increasing the

ozone exposure time up to 1 hour as seen in Figure 6 However 6 log of inactivation was

obtained when subjecting the filtrate to 30 min of ozonation The average TVC after

ozonation was 6times103 CFU100 ml Increasing ozone contact time to 1 hour did not further

inactivate TVC In references 25 30 52 similar observations were made where there were no

further changes in the FC inactivation when the ozone exposure time was increased from

2 to 10 min and from 5 to 15 min In references 55 56 increasing ozonation time from 10 to

40 min did not result in further bacterial reduction

Figure 6 TVC progress as a function of ozonation exposure

The few TVC that remained alive after 30 min of ozone exposure could be resistant to

ozone These TVC could have developed defence mechanisms against ozone and be

resistant to its oxidation 57 58[52] producing ozone resistant coatings 59 or the formation of

ozone resistant pigments and biofilms 56 Microbes could also have remained within the

suspended solids left in wastewater where the solids acted as a barrier against ozone

oxidation 55 57 The setup of the ozonation chamber may have also played a role in the

mixing and transfer efficiency of ozone in wastewater 60 resulting in a lower TVC

removal It is important to mention that after 30 min contact time with ozone all the TVC

values in the wastewater were below the drinking water limit set by the European

Commission at 100 CFUml 54

Filtration had negligible effect on TC and TVC contrary to what was reported by Liberti

et al 52 According to their report 1 log difference on bacterial inactivation was achieved

between clarified and clarified-filtered feeds when using a multilayer pressure filter (deep

bed sand filter) filled with high purity silica sand and gravel The difference between the

results could be explain by the better solid removal efficiency of the deep bed sand filter

compared to the filter paper used in the present study as well as the applied ozone dose

Liberti et al 52 used an ozone dose between 7 and 15 mg O3L while in this study a much

higher ozone dose was applied (71 mg O3L) Such a high ozone dose could have led to

the inactivation of almost all the microorganisms (lt100 CFUml) regardless the amount

of TSS before ozonation Thus comparing the amount of TSS between the 24 h ASP

HRT (24 mgL) and 12 h ASP HRT (60 mgL) no difference in the final TVC was

measured after ozonating both feeds At the same time Venosa et al 60 concluded that

filtration improves substantially coliform (total and faecal) inactivation if secondary

effluent is of poor quality while not being necessary effluent filtration before ozonation if

total COD values are already low enough In this study a negligible difference in COD

was measured between filtered (178 mgL) and non-filtered (179 mgL) feeds agreeing

with the conclusion drawn by Venosa et al 60

34 Process analysis and assessment

In the combined AFO system filtration had no significant effect on organic matter and TSS

removal while ozonation worked as a polishing step on the reduction of COD BOD and TSS

Filtration however showed the potential to reduce the aforementioned parameters for the non-

steady state ASP effluent and therefore it could work as a backup process along with ozone if

the ASP fails At the same time the ASP HRT could be further reduced with a minimal effect on

substrate (BOD) removal efficiency increasing the overall efficiency of the process

On the other hand ozone was highly effective in microorganisms inactivation reducing TC and

TVC values below drinking water standards 54 Neither filtration nor ASP HRT reduction made a

significant difference in the final disinfection efficiency considering the high disinfection

potential of ozone and the applied dose

Based on the results presented in the study and considering the possible improvements for the

ASP (eg SRT and HRT adjustment nitrogen reduction etc) and the ozonation chamber (eg

increase ozone transfer efficiency) it is reasonable to say that the combined AFO system has the

potential to reach water reuse levels or even meet drinking water standards when treating abattoir

wastewater

4 Conclusions

The experimental results obtained in the AFO system proved the process is effective in reducing

organic load as well as TSS P and microbial content

COD and BOD reduction by 93 (128 mgL) and 98 (12 mgL) respectively

TSS and P reduction by 99 (3 mgL) and 98 (19 mgL) respectively

A complete inactivation (100) of TC after 10 min of ozonation

6 log reduction of TVC after 30 min of ozonation

Additionally no appreciable difference was observed between filtered and non-filtered systems

once the ASP reached the steady state For the two ASP HRTs under investigation 24 h and 12 h

and excluding TSS values no difference was found Increasing ozonation exposure from 30

minutes to 1 hour did not improve the overall efficiency of the process

Overall the combined process was sufficient to meet discharge requirements without further

treatment for the measured parameters (COD BOD TSS P TC and TVC)

Acknowledgements

We thank Worldwide Industries Pte Ltd for financial support We also acknowledge Mr C Burt and

Mr B Gibbons for their help as well as Dr D Herrera for his comments and feedback

References

1 Janex M L Xu P Savoye P Laine J M Lazarova V In Ozonation as a wastewater

disinfection process to meet reuse regulations Proceedings of the ozone world congress 1999

International ozone association 1999 pp 81-92

2 Council Directive 91271EEC concerning urban waste-water treatment L 30 European

Commission In 1991 pp 40-52

3 Amec Foster Wheeler Environment amp Infrastructure UK Ltd I ACTeon IMDEA and

NTUA EU-level instruments on water reuse European Comission In Publications Office of the

European Union Luxembourg 2016

4 Gerbens-Leenes P W Mekonnen M M Hoekstra A Y The water footprint of poultry

pork and beef A comparative study in different countries and production systems Water Resources

and Industry 2013 1-2 25-36

5 Rami Z Water and energy use and wastewater production in a beef packing plant MSc

thesis University of Nebraska-Lincoln 2015

6 Mekonnen M M Hoekstra A Y The green blue and grey water footprint of crops and

derived crop products UNESCO-IHE Delft The Netherlands Value of Water Research Report

Series 2010

7 Mekonnen M M Hoekstra A Y A global assessment of the water fooprint of farm animal

products Ecosystems 2012 15 401-415

8 Arvanitoyannis I S Ladas D Meat waste treatment methods and potential uses

International Journal of Food Science amp Technology 2008 43 (3) 543-559

9 Padilla-Gasca E Lopez-Lopez A Gallardo-Valdez J Evaluation of Stability Factors in

the Anaerobic Treatment of Slaughterhouse Wastewater Journal of Bioremediation amp

Biodegradation 2011 02 (01)

10 Bustillo-Lecompte C F Mehrvar M Treatment of an actual slaughterhouse wastewater by

integration of biological and advanced oxidation processes Modeling optimization and cost-

effectiveness analysis Journal of Environmental Management 2016 182 651-66

11 Wu J Doan H Disinfection of recycled red-meat-processing wastewater by ozone Journal

of Chemical Technology amp Biotechnology 2005 80 (7) 828-833

12 Travers S M Lovett D A Activated sludge treatment of abattoir wastewater-II Influence

of dissolved oxygen concentration Water research 1984 18 (4) 435-439

13 Al-Mutairi N Z Al-Sharifi F A Al-Shammari S B Evaluation study of a slaughterhouse

wastewater treatment plant including contact-assisted activated sludge and DAF Desalination 2008

225 (1-3) 167-175

14 Paboacuten S L Suaacuterez Geacutelvez J H Starting-up operating a full-scale activated sludge system

for slaughterhouse wastewater Revista Ingenieriacutea e Investigacioacuten 2009 29 (2) 53-58

15 Johns M R Developments in wastewater treatment in the meat processing industry a

review Bioresource technology 1995 54 (3) 203-216

16 Hsiao T H Huang J S Huang Y I Process kinetics of an activated-sludge reactor

system treating poultry slaughterhouse wastewater Environ Technol 2012 33 (7-9) 829-35

17 Chen C K Lo S L Treatment of slaughterhouse wastewater using an activated

sludgecontact aeration process Water Science amp Technology 2003 47 (12) 285-292

18 Um M M Barraud O Kerouredan M Gaschet M Stalder T Oswald E Dagot C

Ploy M C Brugere H Bibbal D Comparison of the incidence of pathogenic and antibiotic-

resistant Escherichia coli strains in adult cattle and veal calf slaughterhouse effluents highlighted

different risks for public health Water Research 2016 88 30-8

19 Heddle J F Activated sludge treatment of slaughterhouse wastes with protein recovery

Water research 1979 13 581-584

20 Gehr R Wagner M Veerasubramanian P Payment P Disinfection efficiency of

peracetic acid UV and ozone after enhanced primary treatment of municipal wastewater Water

Research 2003 37 (19) 4573-4586

21 Gehr R Wright H UV disinfection of wastewater coagulated with ferric chloride

recalcitrance and fouling problems Water Science amp Technology 1998 38 (3) 15-23

22 Lazarova V Janex M L Fiksdal L Oberg C Barcina I Pommepuy M Advanced

wastewater disinfection technologies short and long term efficiency Water Science amp Technology

1998 38 (12) 109-117

23 Paraskeva P Graham N J D Treatment of a secondary municipal effluent by ozone UV

and microfiltration microbial reduction and effect on effluent quality Desalination 2005 186 (1-3)

47-56

24 Tripathi S Pathak V Tripathi D M Tripathi B D Application of ozone based

treatments of secondary effluents Bioresource Technology 2011 102 (3) 2481-6

25 Lazarova V Liechti P-A Savoye P Hausler R Ozone disinfection main parameters for

process design in wastewater treatment and reuse Journal of Water Reuse and Desalination 2013 3

(4) 337

26 Absi F Gamache F Gehr R Liechti P Nicell J Pilot plant investigation of ozone

disinfection of physico-chemically treatedmunicipal wastewater Ozone Water Wastewater Treatment

1993 1 (7) 33-42

27 Langlais B Legube B Beuffe H Dore M Study of the nature of the by-products formed

and the risks of toxicity when disinfecting a secondary effluent with ozone Water Science amp

Technology 1992 25 (12) 135-143

28 Nebel C Gottschling D Hutchinson R L McBride T J Taylor D M Pavoni J L

Tittlebaum M E Spencer H E Fleischman M Ozone disinfection of industrial municipal

secondary effluents Water pollution control federation 1974 45 (12) 2493-2507

29 Pavoni J L Tittlebaum M E Spencer H E Fleischman M Nebel C Gottschling D

Virus removal from wastewater using ozone Water and sewage works 1972 119 (12) 59-67

30 Xu P Janex M-L Savoye P Cockx A Lazarova V Wastewater disinfection by ozone

main parameters for process design Water Research 2002 36 (4) 1043-1055

31 Millamena O M Ozone treatment of slaughterhouse and laboratory wastewaters

Aquacultural Engineering 1991 11 23-31

32 Roux A Renovation of wastewater for direct re-use in an abattoir MSc thesis University of

Pretoria 1996

33 Proesmans P De Vil R Gerards R Vriends L Advanced treatment of industrial

wastewaters combination of biological treatment and ozonation Mededelingen-faculteit

landbouwkundige en toegepaste biologische wetenschappen 1997 62 (4) 1729-1736

34 APHA American Public Health Association Standard Methods for the Examination of

Water and Wastewater 20 ed Washington DC 1998

35 Al-Mutairi N Z Hamoda M F Al-Ghusain I A Performance-Based Characterization of

a Contact Stabilization Process for Slaughterhouse Wastewater Journal of Environmental Science

and Health Part A 2003 38 (10) 2287-2300

36 Fongsatitkul P Wareham D G Elefsiniotis P Charoensuk P Treatment of a

slaughterhouse wastewater effect of internal recycle rate on chemical oxygen demand total Kjeldahl

nitrogen and total phosphorus removal Environmental Technology 2011 32 (15) 1755-1759

37 Environmental Protection Agency Wastewater treatment manuals Primary secondary and

tertiary treatment Ardcavan Wexford Ireland 1997

38 Lovett D A Travers S M Davey K R Activated sludge treatment of abattoir

wastewater-I Influence of sludge age and feeding pattern Water Research 1984 18 (4) 429-434

39 Abbas H Seif H Moursy A Effect of hydraulic retention time on the activated sludge

system In Sixth International Water Technology Conference Alexandria Egypt 2001 pp 277-284

40 Zhang Y Wang X Hu M Li P Effect of hydraulic retention time (HRT) on the

biodegradation of trichloroethylene wastewater and anaerobic bacterial community in the UASB

reactor Applied microbiology biotechnology 2015 99 (4) 1977-87

41 Martiacutenez S B Peacuterez-Parra J Suay R Use of Ozone in Wastewater Treatment to Produce

Water Suitable for Irrigation Water Resources Management 2011 25 (9) 2109-2124

42 Gerardi M Settleability problems and loss of solids in the activated sludge process New

Jersey USA John Wiley and Sons 2002 179 p 2002

43 Paraskeva P Lambert S D Graham N J D Influence of Ozonation Conditions on the

Treatability of Secondary Effluents Ozone Science amp Engineering 1998 20 (2) 133-150

44 Bustillo-Lecompte C F Mehrvar M Quinones-Bolanos E Combined anaerobic-aerobic

and UVH2O2 processes for the treatment of synthetic slaughterhouse wastewater Environmental

Science and Health Part A Toxichazardous substances amp environmetal engineering 2013 48 (9)

1122-35

45 von Gunten U Ozonation of drinking water Part I Oxidation kinetics and product

formation Water Research 2003 37 (7) 1443-1467

46 Jin X Peldszus S Huck P M Reaction kinetics of selected micropollutants in ozonation

and advanced oxidation processes Water Research 2012 46 (19) 6519-30

47 Masten S J Davies S H R The use of ozonation to degrade organic contaminants in

wastewaters Environmental science amp technology 1994 28 (4) 180-185

48 Gray N F Ozone disinfection In Microbiology of waterborne diseases ElsevierAcademic

Press 2014 pp 599-615

49 Wu P F Mittal G S Characterization of provincial inspected slaughterhouse wastewater

in Ontario Canada Canadian biosystems engineering 2001 53 (6) 9-18

50 Finch G R Smith D W Ozone dose-response of Escherichia coli in activated sludge

effluent Water Research 1989 23 (8) 1017-1025

51 Arayan L Alisha W B Reyes Huynh T Hop Huy T Xuan Eun J Baek Han S Yang

Hong H Chang Suk Kim Antimicrobial effect of different concentrations of ozonate water in the

sanitation of water experimentally inoculated with Escherichia coli Preventive Veterinary Medicine

2017 41 (2) 84-87

52 Liberti L Notarnicola M Lopez A Advanced Treatment For Municipal Wastewater

Reuse In Agriculture III - Ozone Disinfection Ozone Science amp Engineering 2000 22 (2) 151-166

53 Mara D Cairncross S Guidelines for the safe use of wastewater and excreta in agriculture

and aquaculture In World Health Organization Geneva 1989

54 Council Directive 9883EC on the quality of water intended for human consumption O

European Union In 1998 p 42

55 Dietrich J P Loge F J Ginn T R Basagaoglu H Inactivation of particle-associated

microorganisms in wastewater disinfection modeling of ozone and chlorine reactive diffusive

transport in polydispersed suspensions Water Research 2007 41 (10) 2189-201

56 Hess S Gallert C Sensitivity of antibiotic resistant and antibiotic susceptible Escherichia

coli Enterococcus and Staphylococcus strains against ozone Water Health 2015 13 (4) 1020-8

57 Patil S Bourke P Frias J M Tiwari B K Cullen P J Inactivation of Escherichia coli

in orange juice using ozone Innovative Food Science amp Emerging Technologies 2009 10 (4) 551-

557

58 Czekalski N Imminger S Salhi E Veljkovic M Kleffel K Drissner D Hammes F

Burgmann H von Gunten U Inactivation of Antibiotic Resistant Bacteria and Resistance Genes by

Ozone From Laboratory Experiments to Full-Scale Wastewater Treatment Environmental Science amp

Technology 2016 50 (21) 11862-11871

59 Young S B Setlow P Mechanisms of Bacillus subtilis spore resistance to and killing by

aqueous ozone Applied microbiology 2004 96 (5) 1133-42

60 Venosa A D Meckes M C Opatken E J Disinfection of filtered and unfiltered

secondary effluent in two ozone contactors Environment International 1981 4 299-311

As observed with carbon filtration by 4-7 microm pore size filter paper did not reduce TSS and

neither did increasing ozone exposure time However from the experimental results obtained

during the preliminary phase (non-steady state for the ASP) a notable reduction in all the

measured parameters (COD BOD TSS and P) was obtained after filtration compared to those

before the filtration step During this non-steady state phase COD was reduced from 270 plusmn 15

mgL to 230 plusmn 10 mgL BOD from 31 plusmn 10 mgL to 15plusmn1 TSS from 30 plusmn 3 mgL to 16 plusmn 5 mgL

and P from 17 plusmn 5 mgL to 10 plusmn 5 mgL Therefore it could be underlined that filtration could

work as a backup process along with ozonation if the ASP fails

Analysing samples from the 12 h HRT in the ASP TSS reduction after the combined system falls

to 90 in comparison to that of 24 h HRT (988) with a final value of 22 mgL after the AFO

This value is notably higher than the value of 3 mgL for the 24 h HRT A similar explanation

used to address the different BOD results could be applied to the TSS That is in the 12 h HRT

ASP bacteria had less time to degrade the solids in the raw influent leading to a higher value in

the ASP effluent (24 mgL and 60 mgL after 24 h and 12 h HRT ASP respectively) Therefore

decreasing HRT could have adversely affected the solubilisation of colloidal and particulate

BOD resulting in the increase in the final TSS 42

P analyses show post ozonation values in the order of 19 plusmn 1 mgL (984 reduction) The ASP

reduced P values down to 195 plusmn 7 mgL (83) further lowering P values to 132 plusmn 9 mgL

(885) with filtration As observed with TSS increasing ozone contact time did not further

decrease P The change in ASP HRT did not make a significant difference either

In regards to pH raw wastewater samples had a pH of around 53 while the pH throughout the

AFO process ranged between 79 and 83 agreeing with already published data 28 41 43 pH

increase could be attributed to the formation of free ammonia during the ASP and its subsequent

reaction with CO2 produced during the aerobic process This results in ammonium bicarbonate

increasing alkalinity and generating a buffering capacity in the system 9

The total dissolved nitrogen content was also measured and found a reduction of 30 (from 224 plusmn

95 mgL for raw wastewater) after the ASP and maintained at a constant value of 160 plusmn 27 mgL

throughout the rest of the process Ammonia (NH4-N) reduction also happened mainly in the

bioreactor reducing NH4-N by 22 and reaching a constant value of 116 plusmn 12 mgL during

filtration and ozonation Finally nitrate was reduced by 85 during the biological step achieving

a value of 2 plusmn 1 mgL after the ASP The ASP was not design for nitrogen removal and therefore

the efficiency obtained in the AFO was lower than those found in the literature for nitrogen

reduction 19 36 38 44

331Microbial counts

During ozonation oxidation can occur through direct reaction involving molecular ozone and

via an indirect pathway through hydroxyl radicals (OH) formed during ozone decomposition

The former selectively attacks organic compounds while the latter hydroxyl radicals reacts

non-selectively with many dissolved compounds (organic and inorganic contaminants) and

the water matrix 20 45-48 By oxidation of the specific cell wall components ozone disinfects

water and kills bacteria 48

To assess disinfection efficiency samples were analysed for TC and TVC Prior to the

ozonation step the average values of TC and TVC in the filtrate were found to be 14times104

CFU100 ml and 46times109 CFU100 ml respectively Similar values were reported in the

literature 9 18 49

3311 Total Coliforms

In this study a complete inactivation of TC (4 log reduction) was achieved after dosing

the filtrate samples with ozone at 71 plusmn 17 mg O3L for 10 minutes (Figure 5) In the

literature 1 50 it is reported that up to 6 log of bacterial inactivation (Faecal Coliforms TC

and E coli mainly) were achieved after having ozonised industrial or municipal

wastewater Additionally Figure 5 shows that within the first two minutes of ozonation

the number of TC remained constant This behaviour is attributed to the presence of a

high amount of organic matter as Arayan et al 51 reported They found no bacterial

inactivation in the first minute of ozone exposure time when using 001 and 0001

fetal bovine serum (FBS) as organic matter However when the FBS concentration was

decreased to 00001 bacterial inactivation was observed within the first minute of

ozonation In the same way Liberti et al 52 showed a sudden bacterial disinfection within

the first 01 minute with a total dissolved organic carbon value of 7 mgL which is much

lower in comparison to the carbon values reported in this study Xu et al30 also reported

the importance of organic matter on ozone demand and inactivation time

Neither filtration nor ASP HRT reduction significantly affected the final disinfection

efficiency (a complete inactivation of TC was achieved with and without filtration for

both 12 h and 24 h ASP HRT after applying ozone for 10 min)

Figure 5 TC progress as a function of ozonation exposure

The World Health Organisation (WHO) recommends less than 1000 geometric mean

number of faecal coliforms per 100 ml for unrestricted irrigation for edible crops sports

fields and public parks 53 When it comes to drinking water standards the maximum

acceptable concentration of TC is zero per 100 ml noting that for water put into bottles or

containers the limit is set at zero per 250 ml 54 Both limits were met after an ozone

contact time of 10 minutes in the AFO system

3312 Total Viable Counts

On the contrary ozone could not completely remove TVC even after increasing the

ozone exposure time up to 1 hour as seen in Figure 6 However 6 log of inactivation was

obtained when subjecting the filtrate to 30 min of ozonation The average TVC after

ozonation was 6times103 CFU100 ml Increasing ozone contact time to 1 hour did not further

inactivate TVC In references 25 30 52 similar observations were made where there were no

further changes in the FC inactivation when the ozone exposure time was increased from

2 to 10 min and from 5 to 15 min In references 55 56 increasing ozonation time from 10 to

40 min did not result in further bacterial reduction

Figure 6 TVC progress as a function of ozonation exposure

The few TVC that remained alive after 30 min of ozone exposure could be resistant to

ozone These TVC could have developed defence mechanisms against ozone and be

resistant to its oxidation 57 58[52] producing ozone resistant coatings 59 or the formation of

ozone resistant pigments and biofilms 56 Microbes could also have remained within the

suspended solids left in wastewater where the solids acted as a barrier against ozone

oxidation 55 57 The setup of the ozonation chamber may have also played a role in the

mixing and transfer efficiency of ozone in wastewater 60 resulting in a lower TVC

removal It is important to mention that after 30 min contact time with ozone all the TVC

values in the wastewater were below the drinking water limit set by the European

Commission at 100 CFUml 54

Filtration had negligible effect on TC and TVC contrary to what was reported by Liberti

et al 52 According to their report 1 log difference on bacterial inactivation was achieved

between clarified and clarified-filtered feeds when using a multilayer pressure filter (deep

bed sand filter) filled with high purity silica sand and gravel The difference between the

results could be explain by the better solid removal efficiency of the deep bed sand filter

compared to the filter paper used in the present study as well as the applied ozone dose

Liberti et al 52 used an ozone dose between 7 and 15 mg O3L while in this study a much

higher ozone dose was applied (71 mg O3L) Such a high ozone dose could have led to

the inactivation of almost all the microorganisms (lt100 CFUml) regardless the amount

of TSS before ozonation Thus comparing the amount of TSS between the 24 h ASP

HRT (24 mgL) and 12 h ASP HRT (60 mgL) no difference in the final TVC was

measured after ozonating both feeds At the same time Venosa et al 60 concluded that

filtration improves substantially coliform (total and faecal) inactivation if secondary

effluent is of poor quality while not being necessary effluent filtration before ozonation if

total COD values are already low enough In this study a negligible difference in COD

was measured between filtered (178 mgL) and non-filtered (179 mgL) feeds agreeing

with the conclusion drawn by Venosa et al 60

34 Process analysis and assessment

In the combined AFO system filtration had no significant effect on organic matter and TSS

removal while ozonation worked as a polishing step on the reduction of COD BOD and TSS

Filtration however showed the potential to reduce the aforementioned parameters for the non-

steady state ASP effluent and therefore it could work as a backup process along with ozone if

the ASP fails At the same time the ASP HRT could be further reduced with a minimal effect on

substrate (BOD) removal efficiency increasing the overall efficiency of the process

On the other hand ozone was highly effective in microorganisms inactivation reducing TC and

TVC values below drinking water standards 54 Neither filtration nor ASP HRT reduction made a

significant difference in the final disinfection efficiency considering the high disinfection

potential of ozone and the applied dose

Based on the results presented in the study and considering the possible improvements for the

ASP (eg SRT and HRT adjustment nitrogen reduction etc) and the ozonation chamber (eg

increase ozone transfer efficiency) it is reasonable to say that the combined AFO system has the

potential to reach water reuse levels or even meet drinking water standards when treating abattoir

wastewater

4 Conclusions

The experimental results obtained in the AFO system proved the process is effective in reducing

organic load as well as TSS P and microbial content

COD and BOD reduction by 93 (128 mgL) and 98 (12 mgL) respectively

TSS and P reduction by 99 (3 mgL) and 98 (19 mgL) respectively

A complete inactivation (100) of TC after 10 min of ozonation

6 log reduction of TVC after 30 min of ozonation

Additionally no appreciable difference was observed between filtered and non-filtered systems

once the ASP reached the steady state For the two ASP HRTs under investigation 24 h and 12 h

and excluding TSS values no difference was found Increasing ozonation exposure from 30

minutes to 1 hour did not improve the overall efficiency of the process

Overall the combined process was sufficient to meet discharge requirements without further

treatment for the measured parameters (COD BOD TSS P TC and TVC)

Acknowledgements

We thank Worldwide Industries Pte Ltd for financial support We also acknowledge Mr C Burt and

Mr B Gibbons for their help as well as Dr D Herrera for his comments and feedback

References

1 Janex M L Xu P Savoye P Laine J M Lazarova V In Ozonation as a wastewater

disinfection process to meet reuse regulations Proceedings of the ozone world congress 1999

International ozone association 1999 pp 81-92

2 Council Directive 91271EEC concerning urban waste-water treatment L 30 European

Commission In 1991 pp 40-52

3 Amec Foster Wheeler Environment amp Infrastructure UK Ltd I ACTeon IMDEA and

NTUA EU-level instruments on water reuse European Comission In Publications Office of the

European Union Luxembourg 2016

4 Gerbens-Leenes P W Mekonnen M M Hoekstra A Y The water footprint of poultry

pork and beef A comparative study in different countries and production systems Water Resources

and Industry 2013 1-2 25-36

5 Rami Z Water and energy use and wastewater production in a beef packing plant MSc

thesis University of Nebraska-Lincoln 2015

6 Mekonnen M M Hoekstra A Y The green blue and grey water footprint of crops and

derived crop products UNESCO-IHE Delft The Netherlands Value of Water Research Report

Series 2010

7 Mekonnen M M Hoekstra A Y A global assessment of the water fooprint of farm animal

products Ecosystems 2012 15 401-415

8 Arvanitoyannis I S Ladas D Meat waste treatment methods and potential uses

International Journal of Food Science amp Technology 2008 43 (3) 543-559

9 Padilla-Gasca E Lopez-Lopez A Gallardo-Valdez J Evaluation of Stability Factors in

the Anaerobic Treatment of Slaughterhouse Wastewater Journal of Bioremediation amp

Biodegradation 2011 02 (01)

10 Bustillo-Lecompte C F Mehrvar M Treatment of an actual slaughterhouse wastewater by

integration of biological and advanced oxidation processes Modeling optimization and cost-

effectiveness analysis Journal of Environmental Management 2016 182 651-66

11 Wu J Doan H Disinfection of recycled red-meat-processing wastewater by ozone Journal

of Chemical Technology amp Biotechnology 2005 80 (7) 828-833

12 Travers S M Lovett D A Activated sludge treatment of abattoir wastewater-II Influence

of dissolved oxygen concentration Water research 1984 18 (4) 435-439

13 Al-Mutairi N Z Al-Sharifi F A Al-Shammari S B Evaluation study of a slaughterhouse

wastewater treatment plant including contact-assisted activated sludge and DAF Desalination 2008

225 (1-3) 167-175

14 Paboacuten S L Suaacuterez Geacutelvez J H Starting-up operating a full-scale activated sludge system

for slaughterhouse wastewater Revista Ingenieriacutea e Investigacioacuten 2009 29 (2) 53-58

15 Johns M R Developments in wastewater treatment in the meat processing industry a

review Bioresource technology 1995 54 (3) 203-216

16 Hsiao T H Huang J S Huang Y I Process kinetics of an activated-sludge reactor

system treating poultry slaughterhouse wastewater Environ Technol 2012 33 (7-9) 829-35

17 Chen C K Lo S L Treatment of slaughterhouse wastewater using an activated

sludgecontact aeration process Water Science amp Technology 2003 47 (12) 285-292

18 Um M M Barraud O Kerouredan M Gaschet M Stalder T Oswald E Dagot C

Ploy M C Brugere H Bibbal D Comparison of the incidence of pathogenic and antibiotic-

resistant Escherichia coli strains in adult cattle and veal calf slaughterhouse effluents highlighted

different risks for public health Water Research 2016 88 30-8

19 Heddle J F Activated sludge treatment of slaughterhouse wastes with protein recovery

Water research 1979 13 581-584

20 Gehr R Wagner M Veerasubramanian P Payment P Disinfection efficiency of

peracetic acid UV and ozone after enhanced primary treatment of municipal wastewater Water

Research 2003 37 (19) 4573-4586

21 Gehr R Wright H UV disinfection of wastewater coagulated with ferric chloride

recalcitrance and fouling problems Water Science amp Technology 1998 38 (3) 15-23

22 Lazarova V Janex M L Fiksdal L Oberg C Barcina I Pommepuy M Advanced

wastewater disinfection technologies short and long term efficiency Water Science amp Technology

1998 38 (12) 109-117

23 Paraskeva P Graham N J D Treatment of a secondary municipal effluent by ozone UV

and microfiltration microbial reduction and effect on effluent quality Desalination 2005 186 (1-3)

47-56

24 Tripathi S Pathak V Tripathi D M Tripathi B D Application of ozone based

treatments of secondary effluents Bioresource Technology 2011 102 (3) 2481-6

25 Lazarova V Liechti P-A Savoye P Hausler R Ozone disinfection main parameters for

process design in wastewater treatment and reuse Journal of Water Reuse and Desalination 2013 3

(4) 337

26 Absi F Gamache F Gehr R Liechti P Nicell J Pilot plant investigation of ozone

disinfection of physico-chemically treatedmunicipal wastewater Ozone Water Wastewater Treatment

1993 1 (7) 33-42

27 Langlais B Legube B Beuffe H Dore M Study of the nature of the by-products formed

and the risks of toxicity when disinfecting a secondary effluent with ozone Water Science amp

Technology 1992 25 (12) 135-143

28 Nebel C Gottschling D Hutchinson R L McBride T J Taylor D M Pavoni J L

Tittlebaum M E Spencer H E Fleischman M Ozone disinfection of industrial municipal

secondary effluents Water pollution control federation 1974 45 (12) 2493-2507

29 Pavoni J L Tittlebaum M E Spencer H E Fleischman M Nebel C Gottschling D

Virus removal from wastewater using ozone Water and sewage works 1972 119 (12) 59-67

30 Xu P Janex M-L Savoye P Cockx A Lazarova V Wastewater disinfection by ozone

main parameters for process design Water Research 2002 36 (4) 1043-1055

31 Millamena O M Ozone treatment of slaughterhouse and laboratory wastewaters

Aquacultural Engineering 1991 11 23-31

32 Roux A Renovation of wastewater for direct re-use in an abattoir MSc thesis University of

Pretoria 1996

33 Proesmans P De Vil R Gerards R Vriends L Advanced treatment of industrial

wastewaters combination of biological treatment and ozonation Mededelingen-faculteit

landbouwkundige en toegepaste biologische wetenschappen 1997 62 (4) 1729-1736

34 APHA American Public Health Association Standard Methods for the Examination of

Water and Wastewater 20 ed Washington DC 1998

35 Al-Mutairi N Z Hamoda M F Al-Ghusain I A Performance-Based Characterization of

a Contact Stabilization Process for Slaughterhouse Wastewater Journal of Environmental Science

and Health Part A 2003 38 (10) 2287-2300

36 Fongsatitkul P Wareham D G Elefsiniotis P Charoensuk P Treatment of a

slaughterhouse wastewater effect of internal recycle rate on chemical oxygen demand total Kjeldahl

nitrogen and total phosphorus removal Environmental Technology 2011 32 (15) 1755-1759

37 Environmental Protection Agency Wastewater treatment manuals Primary secondary and

tertiary treatment Ardcavan Wexford Ireland 1997

38 Lovett D A Travers S M Davey K R Activated sludge treatment of abattoir

wastewater-I Influence of sludge age and feeding pattern Water Research 1984 18 (4) 429-434

39 Abbas H Seif H Moursy A Effect of hydraulic retention time on the activated sludge

system In Sixth International Water Technology Conference Alexandria Egypt 2001 pp 277-284

40 Zhang Y Wang X Hu M Li P Effect of hydraulic retention time (HRT) on the

biodegradation of trichloroethylene wastewater and anaerobic bacterial community in the UASB

reactor Applied microbiology biotechnology 2015 99 (4) 1977-87

41 Martiacutenez S B Peacuterez-Parra J Suay R Use of Ozone in Wastewater Treatment to Produce

Water Suitable for Irrigation Water Resources Management 2011 25 (9) 2109-2124

42 Gerardi M Settleability problems and loss of solids in the activated sludge process New

Jersey USA John Wiley and Sons 2002 179 p 2002

43 Paraskeva P Lambert S D Graham N J D Influence of Ozonation Conditions on the

Treatability of Secondary Effluents Ozone Science amp Engineering 1998 20 (2) 133-150

44 Bustillo-Lecompte C F Mehrvar M Quinones-Bolanos E Combined anaerobic-aerobic

and UVH2O2 processes for the treatment of synthetic slaughterhouse wastewater Environmental

Science and Health Part A Toxichazardous substances amp environmetal engineering 2013 48 (9)

1122-35

45 von Gunten U Ozonation of drinking water Part I Oxidation kinetics and product

formation Water Research 2003 37 (7) 1443-1467

46 Jin X Peldszus S Huck P M Reaction kinetics of selected micropollutants in ozonation

and advanced oxidation processes Water Research 2012 46 (19) 6519-30

47 Masten S J Davies S H R The use of ozonation to degrade organic contaminants in

wastewaters Environmental science amp technology 1994 28 (4) 180-185

48 Gray N F Ozone disinfection In Microbiology of waterborne diseases ElsevierAcademic

Press 2014 pp 599-615

49 Wu P F Mittal G S Characterization of provincial inspected slaughterhouse wastewater

in Ontario Canada Canadian biosystems engineering 2001 53 (6) 9-18

50 Finch G R Smith D W Ozone dose-response of Escherichia coli in activated sludge

effluent Water Research 1989 23 (8) 1017-1025

51 Arayan L Alisha W B Reyes Huynh T Hop Huy T Xuan Eun J Baek Han S Yang

Hong H Chang Suk Kim Antimicrobial effect of different concentrations of ozonate water in the

sanitation of water experimentally inoculated with Escherichia coli Preventive Veterinary Medicine

2017 41 (2) 84-87

52 Liberti L Notarnicola M Lopez A Advanced Treatment For Municipal Wastewater

Reuse In Agriculture III - Ozone Disinfection Ozone Science amp Engineering 2000 22 (2) 151-166

53 Mara D Cairncross S Guidelines for the safe use of wastewater and excreta in agriculture

and aquaculture In World Health Organization Geneva 1989

54 Council Directive 9883EC on the quality of water intended for human consumption O

European Union In 1998 p 42

55 Dietrich J P Loge F J Ginn T R Basagaoglu H Inactivation of particle-associated

microorganisms in wastewater disinfection modeling of ozone and chlorine reactive diffusive

transport in polydispersed suspensions Water Research 2007 41 (10) 2189-201

56 Hess S Gallert C Sensitivity of antibiotic resistant and antibiotic susceptible Escherichia

coli Enterococcus and Staphylococcus strains against ozone Water Health 2015 13 (4) 1020-8

57 Patil S Bourke P Frias J M Tiwari B K Cullen P J Inactivation of Escherichia coli

in orange juice using ozone Innovative Food Science amp Emerging Technologies 2009 10 (4) 551-

557

58 Czekalski N Imminger S Salhi E Veljkovic M Kleffel K Drissner D Hammes F

Burgmann H von Gunten U Inactivation of Antibiotic Resistant Bacteria and Resistance Genes by

Ozone From Laboratory Experiments to Full-Scale Wastewater Treatment Environmental Science amp

Technology 2016 50 (21) 11862-11871

59 Young S B Setlow P Mechanisms of Bacillus subtilis spore resistance to and killing by

aqueous ozone Applied microbiology 2004 96 (5) 1133-42

60 Venosa A D Meckes M C Opatken E J Disinfection of filtered and unfiltered

secondary effluent in two ozone contactors Environment International 1981 4 299-311

The total dissolved nitrogen content was also measured and found a reduction of 30 (from 224 plusmn

95 mgL for raw wastewater) after the ASP and maintained at a constant value of 160 plusmn 27 mgL

throughout the rest of the process Ammonia (NH4-N) reduction also happened mainly in the

bioreactor reducing NH4-N by 22 and reaching a constant value of 116 plusmn 12 mgL during

filtration and ozonation Finally nitrate was reduced by 85 during the biological step achieving

a value of 2 plusmn 1 mgL after the ASP The ASP was not design for nitrogen removal and therefore

the efficiency obtained in the AFO was lower than those found in the literature for nitrogen

reduction 19 36 38 44

331Microbial counts

During ozonation oxidation can occur through direct reaction involving molecular ozone and

via an indirect pathway through hydroxyl radicals (OH) formed during ozone decomposition

The former selectively attacks organic compounds while the latter hydroxyl radicals reacts

non-selectively with many dissolved compounds (organic and inorganic contaminants) and

the water matrix 20 45-48 By oxidation of the specific cell wall components ozone disinfects

water and kills bacteria 48

To assess disinfection efficiency samples were analysed for TC and TVC Prior to the

ozonation step the average values of TC and TVC in the filtrate were found to be 14times104

CFU100 ml and 46times109 CFU100 ml respectively Similar values were reported in the

literature 9 18 49

3311 Total Coliforms

In this study a complete inactivation of TC (4 log reduction) was achieved after dosing

the filtrate samples with ozone at 71 plusmn 17 mg O3L for 10 minutes (Figure 5) In the

literature 1 50 it is reported that up to 6 log of bacterial inactivation (Faecal Coliforms TC

and E coli mainly) were achieved after having ozonised industrial or municipal

wastewater Additionally Figure 5 shows that within the first two minutes of ozonation

the number of TC remained constant This behaviour is attributed to the presence of a

high amount of organic matter as Arayan et al 51 reported They found no bacterial

inactivation in the first minute of ozone exposure time when using 001 and 0001

fetal bovine serum (FBS) as organic matter However when the FBS concentration was

decreased to 00001 bacterial inactivation was observed within the first minute of

ozonation In the same way Liberti et al 52 showed a sudden bacterial disinfection within

the first 01 minute with a total dissolved organic carbon value of 7 mgL which is much

lower in comparison to the carbon values reported in this study Xu et al30 also reported

the importance of organic matter on ozone demand and inactivation time

Neither filtration nor ASP HRT reduction significantly affected the final disinfection

efficiency (a complete inactivation of TC was achieved with and without filtration for

both 12 h and 24 h ASP HRT after applying ozone for 10 min)

Figure 5 TC progress as a function of ozonation exposure

The World Health Organisation (WHO) recommends less than 1000 geometric mean

number of faecal coliforms per 100 ml for unrestricted irrigation for edible crops sports

fields and public parks 53 When it comes to drinking water standards the maximum

acceptable concentration of TC is zero per 100 ml noting that for water put into bottles or

containers the limit is set at zero per 250 ml 54 Both limits were met after an ozone

contact time of 10 minutes in the AFO system

3312 Total Viable Counts

On the contrary ozone could not completely remove TVC even after increasing the

ozone exposure time up to 1 hour as seen in Figure 6 However 6 log of inactivation was

obtained when subjecting the filtrate to 30 min of ozonation The average TVC after

ozonation was 6times103 CFU100 ml Increasing ozone contact time to 1 hour did not further

inactivate TVC In references 25 30 52 similar observations were made where there were no

further changes in the FC inactivation when the ozone exposure time was increased from

2 to 10 min and from 5 to 15 min In references 55 56 increasing ozonation time from 10 to

40 min did not result in further bacterial reduction

Figure 6 TVC progress as a function of ozonation exposure

The few TVC that remained alive after 30 min of ozone exposure could be resistant to

ozone These TVC could have developed defence mechanisms against ozone and be

resistant to its oxidation 57 58[52] producing ozone resistant coatings 59 or the formation of

ozone resistant pigments and biofilms 56 Microbes could also have remained within the

suspended solids left in wastewater where the solids acted as a barrier against ozone

oxidation 55 57 The setup of the ozonation chamber may have also played a role in the

mixing and transfer efficiency of ozone in wastewater 60 resulting in a lower TVC

removal It is important to mention that after 30 min contact time with ozone all the TVC

values in the wastewater were below the drinking water limit set by the European

Commission at 100 CFUml 54

Filtration had negligible effect on TC and TVC contrary to what was reported by Liberti

et al 52 According to their report 1 log difference on bacterial inactivation was achieved

between clarified and clarified-filtered feeds when using a multilayer pressure filter (deep

bed sand filter) filled with high purity silica sand and gravel The difference between the

results could be explain by the better solid removal efficiency of the deep bed sand filter

compared to the filter paper used in the present study as well as the applied ozone dose

Liberti et al 52 used an ozone dose between 7 and 15 mg O3L while in this study a much

higher ozone dose was applied (71 mg O3L) Such a high ozone dose could have led to

the inactivation of almost all the microorganisms (lt100 CFUml) regardless the amount

of TSS before ozonation Thus comparing the amount of TSS between the 24 h ASP

HRT (24 mgL) and 12 h ASP HRT (60 mgL) no difference in the final TVC was

measured after ozonating both feeds At the same time Venosa et al 60 concluded that

filtration improves substantially coliform (total and faecal) inactivation if secondary

effluent is of poor quality while not being necessary effluent filtration before ozonation if

total COD values are already low enough In this study a negligible difference in COD

was measured between filtered (178 mgL) and non-filtered (179 mgL) feeds agreeing

with the conclusion drawn by Venosa et al 60

34 Process analysis and assessment

In the combined AFO system filtration had no significant effect on organic matter and TSS

removal while ozonation worked as a polishing step on the reduction of COD BOD and TSS

Filtration however showed the potential to reduce the aforementioned parameters for the non-

steady state ASP effluent and therefore it could work as a backup process along with ozone if

the ASP fails At the same time the ASP HRT could be further reduced with a minimal effect on

substrate (BOD) removal efficiency increasing the overall efficiency of the process

On the other hand ozone was highly effective in microorganisms inactivation reducing TC and

TVC values below drinking water standards 54 Neither filtration nor ASP HRT reduction made a

significant difference in the final disinfection efficiency considering the high disinfection

potential of ozone and the applied dose

Based on the results presented in the study and considering the possible improvements for the

ASP (eg SRT and HRT adjustment nitrogen reduction etc) and the ozonation chamber (eg

increase ozone transfer efficiency) it is reasonable to say that the combined AFO system has the

potential to reach water reuse levels or even meet drinking water standards when treating abattoir

wastewater

4 Conclusions

The experimental results obtained in the AFO system proved the process is effective in reducing

organic load as well as TSS P and microbial content

COD and BOD reduction by 93 (128 mgL) and 98 (12 mgL) respectively

TSS and P reduction by 99 (3 mgL) and 98 (19 mgL) respectively

A complete inactivation (100) of TC after 10 min of ozonation

6 log reduction of TVC after 30 min of ozonation

Additionally no appreciable difference was observed between filtered and non-filtered systems

once the ASP reached the steady state For the two ASP HRTs under investigation 24 h and 12 h

and excluding TSS values no difference was found Increasing ozonation exposure from 30

minutes to 1 hour did not improve the overall efficiency of the process

Overall the combined process was sufficient to meet discharge requirements without further

treatment for the measured parameters (COD BOD TSS P TC and TVC)

Acknowledgements

We thank Worldwide Industries Pte Ltd for financial support We also acknowledge Mr C Burt and

Mr B Gibbons for their help as well as Dr D Herrera for his comments and feedback

References

1 Janex M L Xu P Savoye P Laine J M Lazarova V In Ozonation as a wastewater

disinfection process to meet reuse regulations Proceedings of the ozone world congress 1999

International ozone association 1999 pp 81-92

2 Council Directive 91271EEC concerning urban waste-water treatment L 30 European

Commission In 1991 pp 40-52

3 Amec Foster Wheeler Environment amp Infrastructure UK Ltd I ACTeon IMDEA and

NTUA EU-level instruments on water reuse European Comission In Publications Office of the

European Union Luxembourg 2016

4 Gerbens-Leenes P W Mekonnen M M Hoekstra A Y The water footprint of poultry

pork and beef A comparative study in different countries and production systems Water Resources

and Industry 2013 1-2 25-36

5 Rami Z Water and energy use and wastewater production in a beef packing plant MSc

thesis University of Nebraska-Lincoln 2015

6 Mekonnen M M Hoekstra A Y The green blue and grey water footprint of crops and

derived crop products UNESCO-IHE Delft The Netherlands Value of Water Research Report

Series 2010

7 Mekonnen M M Hoekstra A Y A global assessment of the water fooprint of farm animal

products Ecosystems 2012 15 401-415

8 Arvanitoyannis I S Ladas D Meat waste treatment methods and potential uses

International Journal of Food Science amp Technology 2008 43 (3) 543-559

9 Padilla-Gasca E Lopez-Lopez A Gallardo-Valdez J Evaluation of Stability Factors in

the Anaerobic Treatment of Slaughterhouse Wastewater Journal of Bioremediation amp

Biodegradation 2011 02 (01)

10 Bustillo-Lecompte C F Mehrvar M Treatment of an actual slaughterhouse wastewater by

integration of biological and advanced oxidation processes Modeling optimization and cost-

effectiveness analysis Journal of Environmental Management 2016 182 651-66

11 Wu J Doan H Disinfection of recycled red-meat-processing wastewater by ozone Journal

of Chemical Technology amp Biotechnology 2005 80 (7) 828-833

12 Travers S M Lovett D A Activated sludge treatment of abattoir wastewater-II Influence

of dissolved oxygen concentration Water research 1984 18 (4) 435-439

13 Al-Mutairi N Z Al-Sharifi F A Al-Shammari S B Evaluation study of a slaughterhouse

wastewater treatment plant including contact-assisted activated sludge and DAF Desalination 2008

225 (1-3) 167-175

14 Paboacuten S L Suaacuterez Geacutelvez J H Starting-up operating a full-scale activated sludge system

for slaughterhouse wastewater Revista Ingenieriacutea e Investigacioacuten 2009 29 (2) 53-58

15 Johns M R Developments in wastewater treatment in the meat processing industry a

review Bioresource technology 1995 54 (3) 203-216

16 Hsiao T H Huang J S Huang Y I Process kinetics of an activated-sludge reactor

system treating poultry slaughterhouse wastewater Environ Technol 2012 33 (7-9) 829-35

17 Chen C K Lo S L Treatment of slaughterhouse wastewater using an activated

sludgecontact aeration process Water Science amp Technology 2003 47 (12) 285-292

18 Um M M Barraud O Kerouredan M Gaschet M Stalder T Oswald E Dagot C

Ploy M C Brugere H Bibbal D Comparison of the incidence of pathogenic and antibiotic-

resistant Escherichia coli strains in adult cattle and veal calf slaughterhouse effluents highlighted

different risks for public health Water Research 2016 88 30-8

19 Heddle J F Activated sludge treatment of slaughterhouse wastes with protein recovery

Water research 1979 13 581-584

20 Gehr R Wagner M Veerasubramanian P Payment P Disinfection efficiency of

peracetic acid UV and ozone after enhanced primary treatment of municipal wastewater Water

Research 2003 37 (19) 4573-4586

21 Gehr R Wright H UV disinfection of wastewater coagulated with ferric chloride

recalcitrance and fouling problems Water Science amp Technology 1998 38 (3) 15-23

22 Lazarova V Janex M L Fiksdal L Oberg C Barcina I Pommepuy M Advanced

wastewater disinfection technologies short and long term efficiency Water Science amp Technology

1998 38 (12) 109-117

23 Paraskeva P Graham N J D Treatment of a secondary municipal effluent by ozone UV

and microfiltration microbial reduction and effect on effluent quality Desalination 2005 186 (1-3)

47-56

24 Tripathi S Pathak V Tripathi D M Tripathi B D Application of ozone based

treatments of secondary effluents Bioresource Technology 2011 102 (3) 2481-6

25 Lazarova V Liechti P-A Savoye P Hausler R Ozone disinfection main parameters for

process design in wastewater treatment and reuse Journal of Water Reuse and Desalination 2013 3

(4) 337

26 Absi F Gamache F Gehr R Liechti P Nicell J Pilot plant investigation of ozone

disinfection of physico-chemically treatedmunicipal wastewater Ozone Water Wastewater Treatment

1993 1 (7) 33-42

27 Langlais B Legube B Beuffe H Dore M Study of the nature of the by-products formed

and the risks of toxicity when disinfecting a secondary effluent with ozone Water Science amp

Technology 1992 25 (12) 135-143

28 Nebel C Gottschling D Hutchinson R L McBride T J Taylor D M Pavoni J L

Tittlebaum M E Spencer H E Fleischman M Ozone disinfection of industrial municipal

secondary effluents Water pollution control federation 1974 45 (12) 2493-2507

29 Pavoni J L Tittlebaum M E Spencer H E Fleischman M Nebel C Gottschling D

Virus removal from wastewater using ozone Water and sewage works 1972 119 (12) 59-67

30 Xu P Janex M-L Savoye P Cockx A Lazarova V Wastewater disinfection by ozone

main parameters for process design Water Research 2002 36 (4) 1043-1055

31 Millamena O M Ozone treatment of slaughterhouse and laboratory wastewaters

Aquacultural Engineering 1991 11 23-31

32 Roux A Renovation of wastewater for direct re-use in an abattoir MSc thesis University of

Pretoria 1996

33 Proesmans P De Vil R Gerards R Vriends L Advanced treatment of industrial

wastewaters combination of biological treatment and ozonation Mededelingen-faculteit

landbouwkundige en toegepaste biologische wetenschappen 1997 62 (4) 1729-1736

34 APHA American Public Health Association Standard Methods for the Examination of

Water and Wastewater 20 ed Washington DC 1998

35 Al-Mutairi N Z Hamoda M F Al-Ghusain I A Performance-Based Characterization of

a Contact Stabilization Process for Slaughterhouse Wastewater Journal of Environmental Science

and Health Part A 2003 38 (10) 2287-2300

36 Fongsatitkul P Wareham D G Elefsiniotis P Charoensuk P Treatment of a

slaughterhouse wastewater effect of internal recycle rate on chemical oxygen demand total Kjeldahl

nitrogen and total phosphorus removal Environmental Technology 2011 32 (15) 1755-1759

37 Environmental Protection Agency Wastewater treatment manuals Primary secondary and

tertiary treatment Ardcavan Wexford Ireland 1997

38 Lovett D A Travers S M Davey K R Activated sludge treatment of abattoir

wastewater-I Influence of sludge age and feeding pattern Water Research 1984 18 (4) 429-434

39 Abbas H Seif H Moursy A Effect of hydraulic retention time on the activated sludge

system In Sixth International Water Technology Conference Alexandria Egypt 2001 pp 277-284

40 Zhang Y Wang X Hu M Li P Effect of hydraulic retention time (HRT) on the

biodegradation of trichloroethylene wastewater and anaerobic bacterial community in the UASB

reactor Applied microbiology biotechnology 2015 99 (4) 1977-87

41 Martiacutenez S B Peacuterez-Parra J Suay R Use of Ozone in Wastewater Treatment to Produce

Water Suitable for Irrigation Water Resources Management 2011 25 (9) 2109-2124

42 Gerardi M Settleability problems and loss of solids in the activated sludge process New

Jersey USA John Wiley and Sons 2002 179 p 2002

43 Paraskeva P Lambert S D Graham N J D Influence of Ozonation Conditions on the

Treatability of Secondary Effluents Ozone Science amp Engineering 1998 20 (2) 133-150

44 Bustillo-Lecompte C F Mehrvar M Quinones-Bolanos E Combined anaerobic-aerobic

and UVH2O2 processes for the treatment of synthetic slaughterhouse wastewater Environmental

Science and Health Part A Toxichazardous substances amp environmetal engineering 2013 48 (9)

1122-35

45 von Gunten U Ozonation of drinking water Part I Oxidation kinetics and product

formation Water Research 2003 37 (7) 1443-1467

46 Jin X Peldszus S Huck P M Reaction kinetics of selected micropollutants in ozonation

and advanced oxidation processes Water Research 2012 46 (19) 6519-30

47 Masten S J Davies S H R The use of ozonation to degrade organic contaminants in

wastewaters Environmental science amp technology 1994 28 (4) 180-185

48 Gray N F Ozone disinfection In Microbiology of waterborne diseases ElsevierAcademic

Press 2014 pp 599-615

49 Wu P F Mittal G S Characterization of provincial inspected slaughterhouse wastewater

in Ontario Canada Canadian biosystems engineering 2001 53 (6) 9-18

50 Finch G R Smith D W Ozone dose-response of Escherichia coli in activated sludge

effluent Water Research 1989 23 (8) 1017-1025

51 Arayan L Alisha W B Reyes Huynh T Hop Huy T Xuan Eun J Baek Han S Yang

Hong H Chang Suk Kim Antimicrobial effect of different concentrations of ozonate water in the

sanitation of water experimentally inoculated with Escherichia coli Preventive Veterinary Medicine

2017 41 (2) 84-87

52 Liberti L Notarnicola M Lopez A Advanced Treatment For Municipal Wastewater

Reuse In Agriculture III - Ozone Disinfection Ozone Science amp Engineering 2000 22 (2) 151-166

53 Mara D Cairncross S Guidelines for the safe use of wastewater and excreta in agriculture

and aquaculture In World Health Organization Geneva 1989

54 Council Directive 9883EC on the quality of water intended for human consumption O

European Union In 1998 p 42

55 Dietrich J P Loge F J Ginn T R Basagaoglu H Inactivation of particle-associated

microorganisms in wastewater disinfection modeling of ozone and chlorine reactive diffusive

transport in polydispersed suspensions Water Research 2007 41 (10) 2189-201

56 Hess S Gallert C Sensitivity of antibiotic resistant and antibiotic susceptible Escherichia

coli Enterococcus and Staphylococcus strains against ozone Water Health 2015 13 (4) 1020-8

57 Patil S Bourke P Frias J M Tiwari B K Cullen P J Inactivation of Escherichia coli

in orange juice using ozone Innovative Food Science amp Emerging Technologies 2009 10 (4) 551-

557

58 Czekalski N Imminger S Salhi E Veljkovic M Kleffel K Drissner D Hammes F

Burgmann H von Gunten U Inactivation of Antibiotic Resistant Bacteria and Resistance Genes by

Ozone From Laboratory Experiments to Full-Scale Wastewater Treatment Environmental Science amp

Technology 2016 50 (21) 11862-11871

59 Young S B Setlow P Mechanisms of Bacillus subtilis spore resistance to and killing by

aqueous ozone Applied microbiology 2004 96 (5) 1133-42

60 Venosa A D Meckes M C Opatken E J Disinfection of filtered and unfiltered

secondary effluent in two ozone contactors Environment International 1981 4 299-311

high amount of organic matter as Arayan et al 51 reported They found no bacterial

inactivation in the first minute of ozone exposure time when using 001 and 0001

fetal bovine serum (FBS) as organic matter However when the FBS concentration was

decreased to 00001 bacterial inactivation was observed within the first minute of

ozonation In the same way Liberti et al 52 showed a sudden bacterial disinfection within

the first 01 minute with a total dissolved organic carbon value of 7 mgL which is much

lower in comparison to the carbon values reported in this study Xu et al30 also reported

the importance of organic matter on ozone demand and inactivation time

Neither filtration nor ASP HRT reduction significantly affected the final disinfection

efficiency (a complete inactivation of TC was achieved with and without filtration for

both 12 h and 24 h ASP HRT after applying ozone for 10 min)

Figure 5 TC progress as a function of ozonation exposure

The World Health Organisation (WHO) recommends less than 1000 geometric mean

number of faecal coliforms per 100 ml for unrestricted irrigation for edible crops sports

fields and public parks 53 When it comes to drinking water standards the maximum

acceptable concentration of TC is zero per 100 ml noting that for water put into bottles or

containers the limit is set at zero per 250 ml 54 Both limits were met after an ozone

contact time of 10 minutes in the AFO system

3312 Total Viable Counts

On the contrary ozone could not completely remove TVC even after increasing the

ozone exposure time up to 1 hour as seen in Figure 6 However 6 log of inactivation was

obtained when subjecting the filtrate to 30 min of ozonation The average TVC after

ozonation was 6times103 CFU100 ml Increasing ozone contact time to 1 hour did not further

inactivate TVC In references 25 30 52 similar observations were made where there were no

further changes in the FC inactivation when the ozone exposure time was increased from

2 to 10 min and from 5 to 15 min In references 55 56 increasing ozonation time from 10 to

40 min did not result in further bacterial reduction

Figure 6 TVC progress as a function of ozonation exposure

The few TVC that remained alive after 30 min of ozone exposure could be resistant to

ozone These TVC could have developed defence mechanisms against ozone and be

resistant to its oxidation 57 58[52] producing ozone resistant coatings 59 or the formation of

ozone resistant pigments and biofilms 56 Microbes could also have remained within the

suspended solids left in wastewater where the solids acted as a barrier against ozone

oxidation 55 57 The setup of the ozonation chamber may have also played a role in the

mixing and transfer efficiency of ozone in wastewater 60 resulting in a lower TVC

removal It is important to mention that after 30 min contact time with ozone all the TVC

values in the wastewater were below the drinking water limit set by the European

Commission at 100 CFUml 54

Filtration had negligible effect on TC and TVC contrary to what was reported by Liberti

et al 52 According to their report 1 log difference on bacterial inactivation was achieved

between clarified and clarified-filtered feeds when using a multilayer pressure filter (deep

bed sand filter) filled with high purity silica sand and gravel The difference between the

results could be explain by the better solid removal efficiency of the deep bed sand filter

compared to the filter paper used in the present study as well as the applied ozone dose

Liberti et al 52 used an ozone dose between 7 and 15 mg O3L while in this study a much

higher ozone dose was applied (71 mg O3L) Such a high ozone dose could have led to

the inactivation of almost all the microorganisms (lt100 CFUml) regardless the amount

of TSS before ozonation Thus comparing the amount of TSS between the 24 h ASP

HRT (24 mgL) and 12 h ASP HRT (60 mgL) no difference in the final TVC was

measured after ozonating both feeds At the same time Venosa et al 60 concluded that

filtration improves substantially coliform (total and faecal) inactivation if secondary

effluent is of poor quality while not being necessary effluent filtration before ozonation if

total COD values are already low enough In this study a negligible difference in COD

was measured between filtered (178 mgL) and non-filtered (179 mgL) feeds agreeing

with the conclusion drawn by Venosa et al 60

34 Process analysis and assessment

In the combined AFO system filtration had no significant effect on organic matter and TSS

removal while ozonation worked as a polishing step on the reduction of COD BOD and TSS

Filtration however showed the potential to reduce the aforementioned parameters for the non-

steady state ASP effluent and therefore it could work as a backup process along with ozone if

the ASP fails At the same time the ASP HRT could be further reduced with a minimal effect on

substrate (BOD) removal efficiency increasing the overall efficiency of the process

On the other hand ozone was highly effective in microorganisms inactivation reducing TC and

TVC values below drinking water standards 54 Neither filtration nor ASP HRT reduction made a

significant difference in the final disinfection efficiency considering the high disinfection

potential of ozone and the applied dose

Based on the results presented in the study and considering the possible improvements for the

ASP (eg SRT and HRT adjustment nitrogen reduction etc) and the ozonation chamber (eg

increase ozone transfer efficiency) it is reasonable to say that the combined AFO system has the

potential to reach water reuse levels or even meet drinking water standards when treating abattoir

wastewater

4 Conclusions

The experimental results obtained in the AFO system proved the process is effective in reducing

organic load as well as TSS P and microbial content

COD and BOD reduction by 93 (128 mgL) and 98 (12 mgL) respectively

TSS and P reduction by 99 (3 mgL) and 98 (19 mgL) respectively

A complete inactivation (100) of TC after 10 min of ozonation

6 log reduction of TVC after 30 min of ozonation

Additionally no appreciable difference was observed between filtered and non-filtered systems

once the ASP reached the steady state For the two ASP HRTs under investigation 24 h and 12 h

and excluding TSS values no difference was found Increasing ozonation exposure from 30

minutes to 1 hour did not improve the overall efficiency of the process

Overall the combined process was sufficient to meet discharge requirements without further

treatment for the measured parameters (COD BOD TSS P TC and TVC)

Acknowledgements

We thank Worldwide Industries Pte Ltd for financial support We also acknowledge Mr C Burt and

Mr B Gibbons for their help as well as Dr D Herrera for his comments and feedback

References

1 Janex M L Xu P Savoye P Laine J M Lazarova V In Ozonation as a wastewater

disinfection process to meet reuse regulations Proceedings of the ozone world congress 1999

International ozone association 1999 pp 81-92

2 Council Directive 91271EEC concerning urban waste-water treatment L 30 European

Commission In 1991 pp 40-52

3 Amec Foster Wheeler Environment amp Infrastructure UK Ltd I ACTeon IMDEA and

NTUA EU-level instruments on water reuse European Comission In Publications Office of the

European Union Luxembourg 2016

4 Gerbens-Leenes P W Mekonnen M M Hoekstra A Y The water footprint of poultry

pork and beef A comparative study in different countries and production systems Water Resources

and Industry 2013 1-2 25-36

5 Rami Z Water and energy use and wastewater production in a beef packing plant MSc

thesis University of Nebraska-Lincoln 2015

6 Mekonnen M M Hoekstra A Y The green blue and grey water footprint of crops and

derived crop products UNESCO-IHE Delft The Netherlands Value of Water Research Report

Series 2010

7 Mekonnen M M Hoekstra A Y A global assessment of the water fooprint of farm animal

products Ecosystems 2012 15 401-415

8 Arvanitoyannis I S Ladas D Meat waste treatment methods and potential uses

International Journal of Food Science amp Technology 2008 43 (3) 543-559

9 Padilla-Gasca E Lopez-Lopez A Gallardo-Valdez J Evaluation of Stability Factors in

the Anaerobic Treatment of Slaughterhouse Wastewater Journal of Bioremediation amp

Biodegradation 2011 02 (01)

10 Bustillo-Lecompte C F Mehrvar M Treatment of an actual slaughterhouse wastewater by

integration of biological and advanced oxidation processes Modeling optimization and cost-

effectiveness analysis Journal of Environmental Management 2016 182 651-66

11 Wu J Doan H Disinfection of recycled red-meat-processing wastewater by ozone Journal

of Chemical Technology amp Biotechnology 2005 80 (7) 828-833

12 Travers S M Lovett D A Activated sludge treatment of abattoir wastewater-II Influence

of dissolved oxygen concentration Water research 1984 18 (4) 435-439

13 Al-Mutairi N Z Al-Sharifi F A Al-Shammari S B Evaluation study of a slaughterhouse

wastewater treatment plant including contact-assisted activated sludge and DAF Desalination 2008

225 (1-3) 167-175

14 Paboacuten S L Suaacuterez Geacutelvez J H Starting-up operating a full-scale activated sludge system

for slaughterhouse wastewater Revista Ingenieriacutea e Investigacioacuten 2009 29 (2) 53-58

15 Johns M R Developments in wastewater treatment in the meat processing industry a

review Bioresource technology 1995 54 (3) 203-216

16 Hsiao T H Huang J S Huang Y I Process kinetics of an activated-sludge reactor

system treating poultry slaughterhouse wastewater Environ Technol 2012 33 (7-9) 829-35

17 Chen C K Lo S L Treatment of slaughterhouse wastewater using an activated

sludgecontact aeration process Water Science amp Technology 2003 47 (12) 285-292

18 Um M M Barraud O Kerouredan M Gaschet M Stalder T Oswald E Dagot C

Ploy M C Brugere H Bibbal D Comparison of the incidence of pathogenic and antibiotic-

resistant Escherichia coli strains in adult cattle and veal calf slaughterhouse effluents highlighted

different risks for public health Water Research 2016 88 30-8

19 Heddle J F Activated sludge treatment of slaughterhouse wastes with protein recovery

Water research 1979 13 581-584

20 Gehr R Wagner M Veerasubramanian P Payment P Disinfection efficiency of

peracetic acid UV and ozone after enhanced primary treatment of municipal wastewater Water

Research 2003 37 (19) 4573-4586

21 Gehr R Wright H UV disinfection of wastewater coagulated with ferric chloride

recalcitrance and fouling problems Water Science amp Technology 1998 38 (3) 15-23

22 Lazarova V Janex M L Fiksdal L Oberg C Barcina I Pommepuy M Advanced

wastewater disinfection technologies short and long term efficiency Water Science amp Technology

1998 38 (12) 109-117

23 Paraskeva P Graham N J D Treatment of a secondary municipal effluent by ozone UV

and microfiltration microbial reduction and effect on effluent quality Desalination 2005 186 (1-3)

47-56

24 Tripathi S Pathak V Tripathi D M Tripathi B D Application of ozone based

treatments of secondary effluents Bioresource Technology 2011 102 (3) 2481-6

25 Lazarova V Liechti P-A Savoye P Hausler R Ozone disinfection main parameters for

process design in wastewater treatment and reuse Journal of Water Reuse and Desalination 2013 3

(4) 337

26 Absi F Gamache F Gehr R Liechti P Nicell J Pilot plant investigation of ozone

disinfection of physico-chemically treatedmunicipal wastewater Ozone Water Wastewater Treatment

1993 1 (7) 33-42

27 Langlais B Legube B Beuffe H Dore M Study of the nature of the by-products formed

and the risks of toxicity when disinfecting a secondary effluent with ozone Water Science amp

Technology 1992 25 (12) 135-143

28 Nebel C Gottschling D Hutchinson R L McBride T J Taylor D M Pavoni J L

Tittlebaum M E Spencer H E Fleischman M Ozone disinfection of industrial municipal

secondary effluents Water pollution control federation 1974 45 (12) 2493-2507

29 Pavoni J L Tittlebaum M E Spencer H E Fleischman M Nebel C Gottschling D

Virus removal from wastewater using ozone Water and sewage works 1972 119 (12) 59-67

30 Xu P Janex M-L Savoye P Cockx A Lazarova V Wastewater disinfection by ozone

main parameters for process design Water Research 2002 36 (4) 1043-1055

31 Millamena O M Ozone treatment of slaughterhouse and laboratory wastewaters

Aquacultural Engineering 1991 11 23-31

32 Roux A Renovation of wastewater for direct re-use in an abattoir MSc thesis University of

Pretoria 1996

33 Proesmans P De Vil R Gerards R Vriends L Advanced treatment of industrial

wastewaters combination of biological treatment and ozonation Mededelingen-faculteit

landbouwkundige en toegepaste biologische wetenschappen 1997 62 (4) 1729-1736

34 APHA American Public Health Association Standard Methods for the Examination of

Water and Wastewater 20 ed Washington DC 1998

35 Al-Mutairi N Z Hamoda M F Al-Ghusain I A Performance-Based Characterization of

a Contact Stabilization Process for Slaughterhouse Wastewater Journal of Environmental Science

and Health Part A 2003 38 (10) 2287-2300

36 Fongsatitkul P Wareham D G Elefsiniotis P Charoensuk P Treatment of a

slaughterhouse wastewater effect of internal recycle rate on chemical oxygen demand total Kjeldahl

nitrogen and total phosphorus removal Environmental Technology 2011 32 (15) 1755-1759

37 Environmental Protection Agency Wastewater treatment manuals Primary secondary and

tertiary treatment Ardcavan Wexford Ireland 1997

38 Lovett D A Travers S M Davey K R Activated sludge treatment of abattoir

wastewater-I Influence of sludge age and feeding pattern Water Research 1984 18 (4) 429-434

39 Abbas H Seif H Moursy A Effect of hydraulic retention time on the activated sludge

system In Sixth International Water Technology Conference Alexandria Egypt 2001 pp 277-284

40 Zhang Y Wang X Hu M Li P Effect of hydraulic retention time (HRT) on the

biodegradation of trichloroethylene wastewater and anaerobic bacterial community in the UASB

reactor Applied microbiology biotechnology 2015 99 (4) 1977-87

41 Martiacutenez S B Peacuterez-Parra J Suay R Use of Ozone in Wastewater Treatment to Produce

Water Suitable for Irrigation Water Resources Management 2011 25 (9) 2109-2124

42 Gerardi M Settleability problems and loss of solids in the activated sludge process New

Jersey USA John Wiley and Sons 2002 179 p 2002

43 Paraskeva P Lambert S D Graham N J D Influence of Ozonation Conditions on the

Treatability of Secondary Effluents Ozone Science amp Engineering 1998 20 (2) 133-150

44 Bustillo-Lecompte C F Mehrvar M Quinones-Bolanos E Combined anaerobic-aerobic

and UVH2O2 processes for the treatment of synthetic slaughterhouse wastewater Environmental

Science and Health Part A Toxichazardous substances amp environmetal engineering 2013 48 (9)

1122-35

45 von Gunten U Ozonation of drinking water Part I Oxidation kinetics and product

formation Water Research 2003 37 (7) 1443-1467

46 Jin X Peldszus S Huck P M Reaction kinetics of selected micropollutants in ozonation

and advanced oxidation processes Water Research 2012 46 (19) 6519-30

47 Masten S J Davies S H R The use of ozonation to degrade organic contaminants in

wastewaters Environmental science amp technology 1994 28 (4) 180-185

48 Gray N F Ozone disinfection In Microbiology of waterborne diseases ElsevierAcademic

Press 2014 pp 599-615

49 Wu P F Mittal G S Characterization of provincial inspected slaughterhouse wastewater

in Ontario Canada Canadian biosystems engineering 2001 53 (6) 9-18

50 Finch G R Smith D W Ozone dose-response of Escherichia coli in activated sludge

effluent Water Research 1989 23 (8) 1017-1025

51 Arayan L Alisha W B Reyes Huynh T Hop Huy T Xuan Eun J Baek Han S Yang

Hong H Chang Suk Kim Antimicrobial effect of different concentrations of ozonate water in the

sanitation of water experimentally inoculated with Escherichia coli Preventive Veterinary Medicine

2017 41 (2) 84-87

52 Liberti L Notarnicola M Lopez A Advanced Treatment For Municipal Wastewater

Reuse In Agriculture III - Ozone Disinfection Ozone Science amp Engineering 2000 22 (2) 151-166

53 Mara D Cairncross S Guidelines for the safe use of wastewater and excreta in agriculture

and aquaculture In World Health Organization Geneva 1989

54 Council Directive 9883EC on the quality of water intended for human consumption O

European Union In 1998 p 42

55 Dietrich J P Loge F J Ginn T R Basagaoglu H Inactivation of particle-associated

microorganisms in wastewater disinfection modeling of ozone and chlorine reactive diffusive

transport in polydispersed suspensions Water Research 2007 41 (10) 2189-201

56 Hess S Gallert C Sensitivity of antibiotic resistant and antibiotic susceptible Escherichia

coli Enterococcus and Staphylococcus strains against ozone Water Health 2015 13 (4) 1020-8

57 Patil S Bourke P Frias J M Tiwari B K Cullen P J Inactivation of Escherichia coli

in orange juice using ozone Innovative Food Science amp Emerging Technologies 2009 10 (4) 551-

557

58 Czekalski N Imminger S Salhi E Veljkovic M Kleffel K Drissner D Hammes F

Burgmann H von Gunten U Inactivation of Antibiotic Resistant Bacteria and Resistance Genes by

Ozone From Laboratory Experiments to Full-Scale Wastewater Treatment Environmental Science amp

Technology 2016 50 (21) 11862-11871

59 Young S B Setlow P Mechanisms of Bacillus subtilis spore resistance to and killing by

aqueous ozone Applied microbiology 2004 96 (5) 1133-42

60 Venosa A D Meckes M C Opatken E J Disinfection of filtered and unfiltered

secondary effluent in two ozone contactors Environment International 1981 4 299-311

3312 Total Viable Counts

On the contrary ozone could not completely remove TVC even after increasing the

ozone exposure time up to 1 hour as seen in Figure 6 However 6 log of inactivation was

obtained when subjecting the filtrate to 30 min of ozonation The average TVC after

ozonation was 6times103 CFU100 ml Increasing ozone contact time to 1 hour did not further

inactivate TVC In references 25 30 52 similar observations were made where there were no

further changes in the FC inactivation when the ozone exposure time was increased from

2 to 10 min and from 5 to 15 min In references 55 56 increasing ozonation time from 10 to

40 min did not result in further bacterial reduction

Figure 6 TVC progress as a function of ozonation exposure

The few TVC that remained alive after 30 min of ozone exposure could be resistant to

ozone These TVC could have developed defence mechanisms against ozone and be

resistant to its oxidation 57 58[52] producing ozone resistant coatings 59 or the formation of

ozone resistant pigments and biofilms 56 Microbes could also have remained within the

suspended solids left in wastewater where the solids acted as a barrier against ozone

oxidation 55 57 The setup of the ozonation chamber may have also played a role in the

mixing and transfer efficiency of ozone in wastewater 60 resulting in a lower TVC

removal It is important to mention that after 30 min contact time with ozone all the TVC

values in the wastewater were below the drinking water limit set by the European

Commission at 100 CFUml 54

Filtration had negligible effect on TC and TVC contrary to what was reported by Liberti

et al 52 According to their report 1 log difference on bacterial inactivation was achieved

between clarified and clarified-filtered feeds when using a multilayer pressure filter (deep

bed sand filter) filled with high purity silica sand and gravel The difference between the

results could be explain by the better solid removal efficiency of the deep bed sand filter

compared to the filter paper used in the present study as well as the applied ozone dose

Liberti et al 52 used an ozone dose between 7 and 15 mg O3L while in this study a much

higher ozone dose was applied (71 mg O3L) Such a high ozone dose could have led to

the inactivation of almost all the microorganisms (lt100 CFUml) regardless the amount

of TSS before ozonation Thus comparing the amount of TSS between the 24 h ASP

HRT (24 mgL) and 12 h ASP HRT (60 mgL) no difference in the final TVC was

measured after ozonating both feeds At the same time Venosa et al 60 concluded that

filtration improves substantially coliform (total and faecal) inactivation if secondary

effluent is of poor quality while not being necessary effluent filtration before ozonation if

total COD values are already low enough In this study a negligible difference in COD

was measured between filtered (178 mgL) and non-filtered (179 mgL) feeds agreeing

with the conclusion drawn by Venosa et al 60

34 Process analysis and assessment

In the combined AFO system filtration had no significant effect on organic matter and TSS

removal while ozonation worked as a polishing step on the reduction of COD BOD and TSS

Filtration however showed the potential to reduce the aforementioned parameters for the non-

steady state ASP effluent and therefore it could work as a backup process along with ozone if

the ASP fails At the same time the ASP HRT could be further reduced with a minimal effect on

substrate (BOD) removal efficiency increasing the overall efficiency of the process

On the other hand ozone was highly effective in microorganisms inactivation reducing TC and

TVC values below drinking water standards 54 Neither filtration nor ASP HRT reduction made a

significant difference in the final disinfection efficiency considering the high disinfection

potential of ozone and the applied dose

Based on the results presented in the study and considering the possible improvements for the

ASP (eg SRT and HRT adjustment nitrogen reduction etc) and the ozonation chamber (eg

increase ozone transfer efficiency) it is reasonable to say that the combined AFO system has the

potential to reach water reuse levels or even meet drinking water standards when treating abattoir

wastewater

4 Conclusions

The experimental results obtained in the AFO system proved the process is effective in reducing

organic load as well as TSS P and microbial content

COD and BOD reduction by 93 (128 mgL) and 98 (12 mgL) respectively

TSS and P reduction by 99 (3 mgL) and 98 (19 mgL) respectively

A complete inactivation (100) of TC after 10 min of ozonation

6 log reduction of TVC after 30 min of ozonation

Additionally no appreciable difference was observed between filtered and non-filtered systems

once the ASP reached the steady state For the two ASP HRTs under investigation 24 h and 12 h

and excluding TSS values no difference was found Increasing ozonation exposure from 30

minutes to 1 hour did not improve the overall efficiency of the process

Overall the combined process was sufficient to meet discharge requirements without further

treatment for the measured parameters (COD BOD TSS P TC and TVC)

Acknowledgements

We thank Worldwide Industries Pte Ltd for financial support We also acknowledge Mr C Burt and

Mr B Gibbons for their help as well as Dr D Herrera for his comments and feedback

References

1 Janex M L Xu P Savoye P Laine J M Lazarova V In Ozonation as a wastewater

disinfection process to meet reuse regulations Proceedings of the ozone world congress 1999

International ozone association 1999 pp 81-92

2 Council Directive 91271EEC concerning urban waste-water treatment L 30 European

Commission In 1991 pp 40-52

3 Amec Foster Wheeler Environment amp Infrastructure UK Ltd I ACTeon IMDEA and

NTUA EU-level instruments on water reuse European Comission In Publications Office of the

European Union Luxembourg 2016

4 Gerbens-Leenes P W Mekonnen M M Hoekstra A Y The water footprint of poultry

pork and beef A comparative study in different countries and production systems Water Resources

and Industry 2013 1-2 25-36

5 Rami Z Water and energy use and wastewater production in a beef packing plant MSc

thesis University of Nebraska-Lincoln 2015

6 Mekonnen M M Hoekstra A Y The green blue and grey water footprint of crops and

derived crop products UNESCO-IHE Delft The Netherlands Value of Water Research Report

Series 2010

7 Mekonnen M M Hoekstra A Y A global assessment of the water fooprint of farm animal

products Ecosystems 2012 15 401-415

8 Arvanitoyannis I S Ladas D Meat waste treatment methods and potential uses

International Journal of Food Science amp Technology 2008 43 (3) 543-559

9 Padilla-Gasca E Lopez-Lopez A Gallardo-Valdez J Evaluation of Stability Factors in

the Anaerobic Treatment of Slaughterhouse Wastewater Journal of Bioremediation amp

Biodegradation 2011 02 (01)

10 Bustillo-Lecompte C F Mehrvar M Treatment of an actual slaughterhouse wastewater by

integration of biological and advanced oxidation processes Modeling optimization and cost-

effectiveness analysis Journal of Environmental Management 2016 182 651-66

11 Wu J Doan H Disinfection of recycled red-meat-processing wastewater by ozone Journal

of Chemical Technology amp Biotechnology 2005 80 (7) 828-833

12 Travers S M Lovett D A Activated sludge treatment of abattoir wastewater-II Influence

of dissolved oxygen concentration Water research 1984 18 (4) 435-439

13 Al-Mutairi N Z Al-Sharifi F A Al-Shammari S B Evaluation study of a slaughterhouse

wastewater treatment plant including contact-assisted activated sludge and DAF Desalination 2008

225 (1-3) 167-175

14 Paboacuten S L Suaacuterez Geacutelvez J H Starting-up operating a full-scale activated sludge system

for slaughterhouse wastewater Revista Ingenieriacutea e Investigacioacuten 2009 29 (2) 53-58

15 Johns M R Developments in wastewater treatment in the meat processing industry a

review Bioresource technology 1995 54 (3) 203-216

16 Hsiao T H Huang J S Huang Y I Process kinetics of an activated-sludge reactor

system treating poultry slaughterhouse wastewater Environ Technol 2012 33 (7-9) 829-35

17 Chen C K Lo S L Treatment of slaughterhouse wastewater using an activated

sludgecontact aeration process Water Science amp Technology 2003 47 (12) 285-292

18 Um M M Barraud O Kerouredan M Gaschet M Stalder T Oswald E Dagot C

Ploy M C Brugere H Bibbal D Comparison of the incidence of pathogenic and antibiotic-

resistant Escherichia coli strains in adult cattle and veal calf slaughterhouse effluents highlighted

different risks for public health Water Research 2016 88 30-8

19 Heddle J F Activated sludge treatment of slaughterhouse wastes with protein recovery

Water research 1979 13 581-584

20 Gehr R Wagner M Veerasubramanian P Payment P Disinfection efficiency of

peracetic acid UV and ozone after enhanced primary treatment of municipal wastewater Water

Research 2003 37 (19) 4573-4586

21 Gehr R Wright H UV disinfection of wastewater coagulated with ferric chloride

recalcitrance and fouling problems Water Science amp Technology 1998 38 (3) 15-23

22 Lazarova V Janex M L Fiksdal L Oberg C Barcina I Pommepuy M Advanced

wastewater disinfection technologies short and long term efficiency Water Science amp Technology

1998 38 (12) 109-117

23 Paraskeva P Graham N J D Treatment of a secondary municipal effluent by ozone UV

and microfiltration microbial reduction and effect on effluent quality Desalination 2005 186 (1-3)

47-56

24 Tripathi S Pathak V Tripathi D M Tripathi B D Application of ozone based

treatments of secondary effluents Bioresource Technology 2011 102 (3) 2481-6

25 Lazarova V Liechti P-A Savoye P Hausler R Ozone disinfection main parameters for

process design in wastewater treatment and reuse Journal of Water Reuse and Desalination 2013 3

(4) 337

26 Absi F Gamache F Gehr R Liechti P Nicell J Pilot plant investigation of ozone

disinfection of physico-chemically treatedmunicipal wastewater Ozone Water Wastewater Treatment

1993 1 (7) 33-42

27 Langlais B Legube B Beuffe H Dore M Study of the nature of the by-products formed

and the risks of toxicity when disinfecting a secondary effluent with ozone Water Science amp

Technology 1992 25 (12) 135-143

28 Nebel C Gottschling D Hutchinson R L McBride T J Taylor D M Pavoni J L

Tittlebaum M E Spencer H E Fleischman M Ozone disinfection of industrial municipal

secondary effluents Water pollution control federation 1974 45 (12) 2493-2507

29 Pavoni J L Tittlebaum M E Spencer H E Fleischman M Nebel C Gottschling D

Virus removal from wastewater using ozone Water and sewage works 1972 119 (12) 59-67

30 Xu P Janex M-L Savoye P Cockx A Lazarova V Wastewater disinfection by ozone

main parameters for process design Water Research 2002 36 (4) 1043-1055

31 Millamena O M Ozone treatment of slaughterhouse and laboratory wastewaters

Aquacultural Engineering 1991 11 23-31

32 Roux A Renovation of wastewater for direct re-use in an abattoir MSc thesis University of

Pretoria 1996

33 Proesmans P De Vil R Gerards R Vriends L Advanced treatment of industrial

wastewaters combination of biological treatment and ozonation Mededelingen-faculteit

landbouwkundige en toegepaste biologische wetenschappen 1997 62 (4) 1729-1736

34 APHA American Public Health Association Standard Methods for the Examination of

Water and Wastewater 20 ed Washington DC 1998

35 Al-Mutairi N Z Hamoda M F Al-Ghusain I A Performance-Based Characterization of

a Contact Stabilization Process for Slaughterhouse Wastewater Journal of Environmental Science

and Health Part A 2003 38 (10) 2287-2300

36 Fongsatitkul P Wareham D G Elefsiniotis P Charoensuk P Treatment of a

slaughterhouse wastewater effect of internal recycle rate on chemical oxygen demand total Kjeldahl

nitrogen and total phosphorus removal Environmental Technology 2011 32 (15) 1755-1759

37 Environmental Protection Agency Wastewater treatment manuals Primary secondary and

tertiary treatment Ardcavan Wexford Ireland 1997

38 Lovett D A Travers S M Davey K R Activated sludge treatment of abattoir

wastewater-I Influence of sludge age and feeding pattern Water Research 1984 18 (4) 429-434

39 Abbas H Seif H Moursy A Effect of hydraulic retention time on the activated sludge

system In Sixth International Water Technology Conference Alexandria Egypt 2001 pp 277-284

40 Zhang Y Wang X Hu M Li P Effect of hydraulic retention time (HRT) on the

biodegradation of trichloroethylene wastewater and anaerobic bacterial community in the UASB

reactor Applied microbiology biotechnology 2015 99 (4) 1977-87

41 Martiacutenez S B Peacuterez-Parra J Suay R Use of Ozone in Wastewater Treatment to Produce

Water Suitable for Irrigation Water Resources Management 2011 25 (9) 2109-2124

42 Gerardi M Settleability problems and loss of solids in the activated sludge process New

Jersey USA John Wiley and Sons 2002 179 p 2002

43 Paraskeva P Lambert S D Graham N J D Influence of Ozonation Conditions on the

Treatability of Secondary Effluents Ozone Science amp Engineering 1998 20 (2) 133-150

44 Bustillo-Lecompte C F Mehrvar M Quinones-Bolanos E Combined anaerobic-aerobic

and UVH2O2 processes for the treatment of synthetic slaughterhouse wastewater Environmental

Science and Health Part A Toxichazardous substances amp environmetal engineering 2013 48 (9)

1122-35

45 von Gunten U Ozonation of drinking water Part I Oxidation kinetics and product

formation Water Research 2003 37 (7) 1443-1467

46 Jin X Peldszus S Huck P M Reaction kinetics of selected micropollutants in ozonation

and advanced oxidation processes Water Research 2012 46 (19) 6519-30

47 Masten S J Davies S H R The use of ozonation to degrade organic contaminants in

wastewaters Environmental science amp technology 1994 28 (4) 180-185

48 Gray N F Ozone disinfection In Microbiology of waterborne diseases ElsevierAcademic

Press 2014 pp 599-615

49 Wu P F Mittal G S Characterization of provincial inspected slaughterhouse wastewater

in Ontario Canada Canadian biosystems engineering 2001 53 (6) 9-18

50 Finch G R Smith D W Ozone dose-response of Escherichia coli in activated sludge

effluent Water Research 1989 23 (8) 1017-1025

51 Arayan L Alisha W B Reyes Huynh T Hop Huy T Xuan Eun J Baek Han S Yang

Hong H Chang Suk Kim Antimicrobial effect of different concentrations of ozonate water in the

sanitation of water experimentally inoculated with Escherichia coli Preventive Veterinary Medicine

2017 41 (2) 84-87

52 Liberti L Notarnicola M Lopez A Advanced Treatment For Municipal Wastewater

Reuse In Agriculture III - Ozone Disinfection Ozone Science amp Engineering 2000 22 (2) 151-166

53 Mara D Cairncross S Guidelines for the safe use of wastewater and excreta in agriculture

and aquaculture In World Health Organization Geneva 1989

54 Council Directive 9883EC on the quality of water intended for human consumption O

European Union In 1998 p 42

55 Dietrich J P Loge F J Ginn T R Basagaoglu H Inactivation of particle-associated

microorganisms in wastewater disinfection modeling of ozone and chlorine reactive diffusive

transport in polydispersed suspensions Water Research 2007 41 (10) 2189-201

56 Hess S Gallert C Sensitivity of antibiotic resistant and antibiotic susceptible Escherichia

coli Enterococcus and Staphylococcus strains against ozone Water Health 2015 13 (4) 1020-8

57 Patil S Bourke P Frias J M Tiwari B K Cullen P J Inactivation of Escherichia coli

in orange juice using ozone Innovative Food Science amp Emerging Technologies 2009 10 (4) 551-

557

58 Czekalski N Imminger S Salhi E Veljkovic M Kleffel K Drissner D Hammes F

Burgmann H von Gunten U Inactivation of Antibiotic Resistant Bacteria and Resistance Genes by

Ozone From Laboratory Experiments to Full-Scale Wastewater Treatment Environmental Science amp

Technology 2016 50 (21) 11862-11871

59 Young S B Setlow P Mechanisms of Bacillus subtilis spore resistance to and killing by

aqueous ozone Applied microbiology 2004 96 (5) 1133-42

60 Venosa A D Meckes M C Opatken E J Disinfection of filtered and unfiltered

secondary effluent in two ozone contactors Environment International 1981 4 299-311

mixing and transfer efficiency of ozone in wastewater 60 resulting in a lower TVC

removal It is important to mention that after 30 min contact time with ozone all the TVC

values in the wastewater were below the drinking water limit set by the European

Commission at 100 CFUml 54

Filtration had negligible effect on TC and TVC contrary to what was reported by Liberti

et al 52 According to their report 1 log difference on bacterial inactivation was achieved

between clarified and clarified-filtered feeds when using a multilayer pressure filter (deep

bed sand filter) filled with high purity silica sand and gravel The difference between the

results could be explain by the better solid removal efficiency of the deep bed sand filter

compared to the filter paper used in the present study as well as the applied ozone dose

Liberti et al 52 used an ozone dose between 7 and 15 mg O3L while in this study a much

higher ozone dose was applied (71 mg O3L) Such a high ozone dose could have led to

the inactivation of almost all the microorganisms (lt100 CFUml) regardless the amount

of TSS before ozonation Thus comparing the amount of TSS between the 24 h ASP

HRT (24 mgL) and 12 h ASP HRT (60 mgL) no difference in the final TVC was

measured after ozonating both feeds At the same time Venosa et al 60 concluded that

filtration improves substantially coliform (total and faecal) inactivation if secondary

effluent is of poor quality while not being necessary effluent filtration before ozonation if

total COD values are already low enough In this study a negligible difference in COD

was measured between filtered (178 mgL) and non-filtered (179 mgL) feeds agreeing

with the conclusion drawn by Venosa et al 60

34 Process analysis and assessment

In the combined AFO system filtration had no significant effect on organic matter and TSS

removal while ozonation worked as a polishing step on the reduction of COD BOD and TSS

Filtration however showed the potential to reduce the aforementioned parameters for the non-

steady state ASP effluent and therefore it could work as a backup process along with ozone if

the ASP fails At the same time the ASP HRT could be further reduced with a minimal effect on

substrate (BOD) removal efficiency increasing the overall efficiency of the process

On the other hand ozone was highly effective in microorganisms inactivation reducing TC and

TVC values below drinking water standards 54 Neither filtration nor ASP HRT reduction made a

significant difference in the final disinfection efficiency considering the high disinfection

potential of ozone and the applied dose

Based on the results presented in the study and considering the possible improvements for the

ASP (eg SRT and HRT adjustment nitrogen reduction etc) and the ozonation chamber (eg

increase ozone transfer efficiency) it is reasonable to say that the combined AFO system has the

potential to reach water reuse levels or even meet drinking water standards when treating abattoir

wastewater

4 Conclusions

The experimental results obtained in the AFO system proved the process is effective in reducing

organic load as well as TSS P and microbial content

COD and BOD reduction by 93 (128 mgL) and 98 (12 mgL) respectively

TSS and P reduction by 99 (3 mgL) and 98 (19 mgL) respectively

A complete inactivation (100) of TC after 10 min of ozonation

6 log reduction of TVC after 30 min of ozonation

Additionally no appreciable difference was observed between filtered and non-filtered systems

once the ASP reached the steady state For the two ASP HRTs under investigation 24 h and 12 h

and excluding TSS values no difference was found Increasing ozonation exposure from 30

minutes to 1 hour did not improve the overall efficiency of the process

Overall the combined process was sufficient to meet discharge requirements without further

treatment for the measured parameters (COD BOD TSS P TC and TVC)

Acknowledgements

We thank Worldwide Industries Pte Ltd for financial support We also acknowledge Mr C Burt and

Mr B Gibbons for their help as well as Dr D Herrera for his comments and feedback

References

1 Janex M L Xu P Savoye P Laine J M Lazarova V In Ozonation as a wastewater

disinfection process to meet reuse regulations Proceedings of the ozone world congress 1999

International ozone association 1999 pp 81-92

2 Council Directive 91271EEC concerning urban waste-water treatment L 30 European

Commission In 1991 pp 40-52

3 Amec Foster Wheeler Environment amp Infrastructure UK Ltd I ACTeon IMDEA and

NTUA EU-level instruments on water reuse European Comission In Publications Office of the

European Union Luxembourg 2016

4 Gerbens-Leenes P W Mekonnen M M Hoekstra A Y The water footprint of poultry

pork and beef A comparative study in different countries and production systems Water Resources

and Industry 2013 1-2 25-36

5 Rami Z Water and energy use and wastewater production in a beef packing plant MSc

thesis University of Nebraska-Lincoln 2015

6 Mekonnen M M Hoekstra A Y The green blue and grey water footprint of crops and

derived crop products UNESCO-IHE Delft The Netherlands Value of Water Research Report

Series 2010

7 Mekonnen M M Hoekstra A Y A global assessment of the water fooprint of farm animal

products Ecosystems 2012 15 401-415

8 Arvanitoyannis I S Ladas D Meat waste treatment methods and potential uses

International Journal of Food Science amp Technology 2008 43 (3) 543-559

9 Padilla-Gasca E Lopez-Lopez A Gallardo-Valdez J Evaluation of Stability Factors in

the Anaerobic Treatment of Slaughterhouse Wastewater Journal of Bioremediation amp

Biodegradation 2011 02 (01)

10 Bustillo-Lecompte C F Mehrvar M Treatment of an actual slaughterhouse wastewater by

integration of biological and advanced oxidation processes Modeling optimization and cost-

effectiveness analysis Journal of Environmental Management 2016 182 651-66

11 Wu J Doan H Disinfection of recycled red-meat-processing wastewater by ozone Journal

of Chemical Technology amp Biotechnology 2005 80 (7) 828-833

12 Travers S M Lovett D A Activated sludge treatment of abattoir wastewater-II Influence

of dissolved oxygen concentration Water research 1984 18 (4) 435-439

13 Al-Mutairi N Z Al-Sharifi F A Al-Shammari S B Evaluation study of a slaughterhouse

wastewater treatment plant including contact-assisted activated sludge and DAF Desalination 2008

225 (1-3) 167-175

14 Paboacuten S L Suaacuterez Geacutelvez J H Starting-up operating a full-scale activated sludge system

for slaughterhouse wastewater Revista Ingenieriacutea e Investigacioacuten 2009 29 (2) 53-58

15 Johns M R Developments in wastewater treatment in the meat processing industry a

review Bioresource technology 1995 54 (3) 203-216

16 Hsiao T H Huang J S Huang Y I Process kinetics of an activated-sludge reactor

system treating poultry slaughterhouse wastewater Environ Technol 2012 33 (7-9) 829-35

17 Chen C K Lo S L Treatment of slaughterhouse wastewater using an activated

sludgecontact aeration process Water Science amp Technology 2003 47 (12) 285-292

18 Um M M Barraud O Kerouredan M Gaschet M Stalder T Oswald E Dagot C

Ploy M C Brugere H Bibbal D Comparison of the incidence of pathogenic and antibiotic-

resistant Escherichia coli strains in adult cattle and veal calf slaughterhouse effluents highlighted

different risks for public health Water Research 2016 88 30-8

19 Heddle J F Activated sludge treatment of slaughterhouse wastes with protein recovery

Water research 1979 13 581-584

20 Gehr R Wagner M Veerasubramanian P Payment P Disinfection efficiency of

peracetic acid UV and ozone after enhanced primary treatment of municipal wastewater Water

Research 2003 37 (19) 4573-4586

21 Gehr R Wright H UV disinfection of wastewater coagulated with ferric chloride

recalcitrance and fouling problems Water Science amp Technology 1998 38 (3) 15-23

22 Lazarova V Janex M L Fiksdal L Oberg C Barcina I Pommepuy M Advanced

wastewater disinfection technologies short and long term efficiency Water Science amp Technology

1998 38 (12) 109-117

23 Paraskeva P Graham N J D Treatment of a secondary municipal effluent by ozone UV

and microfiltration microbial reduction and effect on effluent quality Desalination 2005 186 (1-3)

47-56

24 Tripathi S Pathak V Tripathi D M Tripathi B D Application of ozone based

treatments of secondary effluents Bioresource Technology 2011 102 (3) 2481-6

25 Lazarova V Liechti P-A Savoye P Hausler R Ozone disinfection main parameters for

process design in wastewater treatment and reuse Journal of Water Reuse and Desalination 2013 3

(4) 337

26 Absi F Gamache F Gehr R Liechti P Nicell J Pilot plant investigation of ozone

disinfection of physico-chemically treatedmunicipal wastewater Ozone Water Wastewater Treatment

1993 1 (7) 33-42

27 Langlais B Legube B Beuffe H Dore M Study of the nature of the by-products formed

and the risks of toxicity when disinfecting a secondary effluent with ozone Water Science amp

Technology 1992 25 (12) 135-143

28 Nebel C Gottschling D Hutchinson R L McBride T J Taylor D M Pavoni J L

Tittlebaum M E Spencer H E Fleischman M Ozone disinfection of industrial municipal

secondary effluents Water pollution control federation 1974 45 (12) 2493-2507

29 Pavoni J L Tittlebaum M E Spencer H E Fleischman M Nebel C Gottschling D

Virus removal from wastewater using ozone Water and sewage works 1972 119 (12) 59-67

30 Xu P Janex M-L Savoye P Cockx A Lazarova V Wastewater disinfection by ozone

main parameters for process design Water Research 2002 36 (4) 1043-1055

31 Millamena O M Ozone treatment of slaughterhouse and laboratory wastewaters

Aquacultural Engineering 1991 11 23-31

32 Roux A Renovation of wastewater for direct re-use in an abattoir MSc thesis University of

Pretoria 1996

33 Proesmans P De Vil R Gerards R Vriends L Advanced treatment of industrial

wastewaters combination of biological treatment and ozonation Mededelingen-faculteit

landbouwkundige en toegepaste biologische wetenschappen 1997 62 (4) 1729-1736

34 APHA American Public Health Association Standard Methods for the Examination of

Water and Wastewater 20 ed Washington DC 1998

35 Al-Mutairi N Z Hamoda M F Al-Ghusain I A Performance-Based Characterization of

a Contact Stabilization Process for Slaughterhouse Wastewater Journal of Environmental Science

and Health Part A 2003 38 (10) 2287-2300

36 Fongsatitkul P Wareham D G Elefsiniotis P Charoensuk P Treatment of a

slaughterhouse wastewater effect of internal recycle rate on chemical oxygen demand total Kjeldahl

nitrogen and total phosphorus removal Environmental Technology 2011 32 (15) 1755-1759

37 Environmental Protection Agency Wastewater treatment manuals Primary secondary and

tertiary treatment Ardcavan Wexford Ireland 1997

38 Lovett D A Travers S M Davey K R Activated sludge treatment of abattoir

wastewater-I Influence of sludge age and feeding pattern Water Research 1984 18 (4) 429-434

39 Abbas H Seif H Moursy A Effect of hydraulic retention time on the activated sludge

system In Sixth International Water Technology Conference Alexandria Egypt 2001 pp 277-284

40 Zhang Y Wang X Hu M Li P Effect of hydraulic retention time (HRT) on the

biodegradation of trichloroethylene wastewater and anaerobic bacterial community in the UASB

reactor Applied microbiology biotechnology 2015 99 (4) 1977-87

41 Martiacutenez S B Peacuterez-Parra J Suay R Use of Ozone in Wastewater Treatment to Produce

Water Suitable for Irrigation Water Resources Management 2011 25 (9) 2109-2124

42 Gerardi M Settleability problems and loss of solids in the activated sludge process New

Jersey USA John Wiley and Sons 2002 179 p 2002

43 Paraskeva P Lambert S D Graham N J D Influence of Ozonation Conditions on the

Treatability of Secondary Effluents Ozone Science amp Engineering 1998 20 (2) 133-150

44 Bustillo-Lecompte C F Mehrvar M Quinones-Bolanos E Combined anaerobic-aerobic

and UVH2O2 processes for the treatment of synthetic slaughterhouse wastewater Environmental

Science and Health Part A Toxichazardous substances amp environmetal engineering 2013 48 (9)

1122-35

45 von Gunten U Ozonation of drinking water Part I Oxidation kinetics and product

formation Water Research 2003 37 (7) 1443-1467

46 Jin X Peldszus S Huck P M Reaction kinetics of selected micropollutants in ozonation

and advanced oxidation processes Water Research 2012 46 (19) 6519-30

47 Masten S J Davies S H R The use of ozonation to degrade organic contaminants in

wastewaters Environmental science amp technology 1994 28 (4) 180-185

48 Gray N F Ozone disinfection In Microbiology of waterborne diseases ElsevierAcademic

Press 2014 pp 599-615

49 Wu P F Mittal G S Characterization of provincial inspected slaughterhouse wastewater

in Ontario Canada Canadian biosystems engineering 2001 53 (6) 9-18

50 Finch G R Smith D W Ozone dose-response of Escherichia coli in activated sludge

effluent Water Research 1989 23 (8) 1017-1025

51 Arayan L Alisha W B Reyes Huynh T Hop Huy T Xuan Eun J Baek Han S Yang

Hong H Chang Suk Kim Antimicrobial effect of different concentrations of ozonate water in the

sanitation of water experimentally inoculated with Escherichia coli Preventive Veterinary Medicine

2017 41 (2) 84-87

52 Liberti L Notarnicola M Lopez A Advanced Treatment For Municipal Wastewater

Reuse In Agriculture III - Ozone Disinfection Ozone Science amp Engineering 2000 22 (2) 151-166

53 Mara D Cairncross S Guidelines for the safe use of wastewater and excreta in agriculture

and aquaculture In World Health Organization Geneva 1989

54 Council Directive 9883EC on the quality of water intended for human consumption O

European Union In 1998 p 42

55 Dietrich J P Loge F J Ginn T R Basagaoglu H Inactivation of particle-associated

microorganisms in wastewater disinfection modeling of ozone and chlorine reactive diffusive

transport in polydispersed suspensions Water Research 2007 41 (10) 2189-201

56 Hess S Gallert C Sensitivity of antibiotic resistant and antibiotic susceptible Escherichia

coli Enterococcus and Staphylococcus strains against ozone Water Health 2015 13 (4) 1020-8

57 Patil S Bourke P Frias J M Tiwari B K Cullen P J Inactivation of Escherichia coli

in orange juice using ozone Innovative Food Science amp Emerging Technologies 2009 10 (4) 551-

557

58 Czekalski N Imminger S Salhi E Veljkovic M Kleffel K Drissner D Hammes F

Burgmann H von Gunten U Inactivation of Antibiotic Resistant Bacteria and Resistance Genes by

Ozone From Laboratory Experiments to Full-Scale Wastewater Treatment Environmental Science amp

Technology 2016 50 (21) 11862-11871

59 Young S B Setlow P Mechanisms of Bacillus subtilis spore resistance to and killing by

aqueous ozone Applied microbiology 2004 96 (5) 1133-42

60 Venosa A D Meckes M C Opatken E J Disinfection of filtered and unfiltered

secondary effluent in two ozone contactors Environment International 1981 4 299-311

the ASP fails At the same time the ASP HRT could be further reduced with a minimal effect on

substrate (BOD) removal efficiency increasing the overall efficiency of the process

On the other hand ozone was highly effective in microorganisms inactivation reducing TC and

TVC values below drinking water standards 54 Neither filtration nor ASP HRT reduction made a

significant difference in the final disinfection efficiency considering the high disinfection

potential of ozone and the applied dose

Based on the results presented in the study and considering the possible improvements for the

ASP (eg SRT and HRT adjustment nitrogen reduction etc) and the ozonation chamber (eg

increase ozone transfer efficiency) it is reasonable to say that the combined AFO system has the

potential to reach water reuse levels or even meet drinking water standards when treating abattoir

wastewater

4 Conclusions

The experimental results obtained in the AFO system proved the process is effective in reducing

organic load as well as TSS P and microbial content

COD and BOD reduction by 93 (128 mgL) and 98 (12 mgL) respectively

TSS and P reduction by 99 (3 mgL) and 98 (19 mgL) respectively

A complete inactivation (100) of TC after 10 min of ozonation

6 log reduction of TVC after 30 min of ozonation

Additionally no appreciable difference was observed between filtered and non-filtered systems

once the ASP reached the steady state For the two ASP HRTs under investigation 24 h and 12 h

and excluding TSS values no difference was found Increasing ozonation exposure from 30

minutes to 1 hour did not improve the overall efficiency of the process

Overall the combined process was sufficient to meet discharge requirements without further

treatment for the measured parameters (COD BOD TSS P TC and TVC)

Acknowledgements

We thank Worldwide Industries Pte Ltd for financial support We also acknowledge Mr C Burt and

Mr B Gibbons for their help as well as Dr D Herrera for his comments and feedback

References

1 Janex M L Xu P Savoye P Laine J M Lazarova V In Ozonation as a wastewater

disinfection process to meet reuse regulations Proceedings of the ozone world congress 1999

International ozone association 1999 pp 81-92

2 Council Directive 91271EEC concerning urban waste-water treatment L 30 European

Commission In 1991 pp 40-52

3 Amec Foster Wheeler Environment amp Infrastructure UK Ltd I ACTeon IMDEA and

NTUA EU-level instruments on water reuse European Comission In Publications Office of the

European Union Luxembourg 2016

4 Gerbens-Leenes P W Mekonnen M M Hoekstra A Y The water footprint of poultry

pork and beef A comparative study in different countries and production systems Water Resources

and Industry 2013 1-2 25-36

5 Rami Z Water and energy use and wastewater production in a beef packing plant MSc

thesis University of Nebraska-Lincoln 2015

6 Mekonnen M M Hoekstra A Y The green blue and grey water footprint of crops and

derived crop products UNESCO-IHE Delft The Netherlands Value of Water Research Report

Series 2010

7 Mekonnen M M Hoekstra A Y A global assessment of the water fooprint of farm animal

products Ecosystems 2012 15 401-415

8 Arvanitoyannis I S Ladas D Meat waste treatment methods and potential uses

International Journal of Food Science amp Technology 2008 43 (3) 543-559

9 Padilla-Gasca E Lopez-Lopez A Gallardo-Valdez J Evaluation of Stability Factors in

the Anaerobic Treatment of Slaughterhouse Wastewater Journal of Bioremediation amp

Biodegradation 2011 02 (01)

10 Bustillo-Lecompte C F Mehrvar M Treatment of an actual slaughterhouse wastewater by

integration of biological and advanced oxidation processes Modeling optimization and cost-

effectiveness analysis Journal of Environmental Management 2016 182 651-66

11 Wu J Doan H Disinfection of recycled red-meat-processing wastewater by ozone Journal

of Chemical Technology amp Biotechnology 2005 80 (7) 828-833

12 Travers S M Lovett D A Activated sludge treatment of abattoir wastewater-II Influence

of dissolved oxygen concentration Water research 1984 18 (4) 435-439

13 Al-Mutairi N Z Al-Sharifi F A Al-Shammari S B Evaluation study of a slaughterhouse

wastewater treatment plant including contact-assisted activated sludge and DAF Desalination 2008

225 (1-3) 167-175

14 Paboacuten S L Suaacuterez Geacutelvez J H Starting-up operating a full-scale activated sludge system

for slaughterhouse wastewater Revista Ingenieriacutea e Investigacioacuten 2009 29 (2) 53-58

15 Johns M R Developments in wastewater treatment in the meat processing industry a

review Bioresource technology 1995 54 (3) 203-216

16 Hsiao T H Huang J S Huang Y I Process kinetics of an activated-sludge reactor

system treating poultry slaughterhouse wastewater Environ Technol 2012 33 (7-9) 829-35

17 Chen C K Lo S L Treatment of slaughterhouse wastewater using an activated

sludgecontact aeration process Water Science amp Technology 2003 47 (12) 285-292

18 Um M M Barraud O Kerouredan M Gaschet M Stalder T Oswald E Dagot C

Ploy M C Brugere H Bibbal D Comparison of the incidence of pathogenic and antibiotic-

resistant Escherichia coli strains in adult cattle and veal calf slaughterhouse effluents highlighted

different risks for public health Water Research 2016 88 30-8

19 Heddle J F Activated sludge treatment of slaughterhouse wastes with protein recovery

Water research 1979 13 581-584

20 Gehr R Wagner M Veerasubramanian P Payment P Disinfection efficiency of

peracetic acid UV and ozone after enhanced primary treatment of municipal wastewater Water

Research 2003 37 (19) 4573-4586

21 Gehr R Wright H UV disinfection of wastewater coagulated with ferric chloride

recalcitrance and fouling problems Water Science amp Technology 1998 38 (3) 15-23

22 Lazarova V Janex M L Fiksdal L Oberg C Barcina I Pommepuy M Advanced

wastewater disinfection technologies short and long term efficiency Water Science amp Technology

1998 38 (12) 109-117

23 Paraskeva P Graham N J D Treatment of a secondary municipal effluent by ozone UV

and microfiltration microbial reduction and effect on effluent quality Desalination 2005 186 (1-3)

47-56

24 Tripathi S Pathak V Tripathi D M Tripathi B D Application of ozone based

treatments of secondary effluents Bioresource Technology 2011 102 (3) 2481-6

25 Lazarova V Liechti P-A Savoye P Hausler R Ozone disinfection main parameters for

process design in wastewater treatment and reuse Journal of Water Reuse and Desalination 2013 3

(4) 337

26 Absi F Gamache F Gehr R Liechti P Nicell J Pilot plant investigation of ozone

disinfection of physico-chemically treatedmunicipal wastewater Ozone Water Wastewater Treatment

1993 1 (7) 33-42

27 Langlais B Legube B Beuffe H Dore M Study of the nature of the by-products formed

and the risks of toxicity when disinfecting a secondary effluent with ozone Water Science amp

Technology 1992 25 (12) 135-143

28 Nebel C Gottschling D Hutchinson R L McBride T J Taylor D M Pavoni J L

Tittlebaum M E Spencer H E Fleischman M Ozone disinfection of industrial municipal

secondary effluents Water pollution control federation 1974 45 (12) 2493-2507

29 Pavoni J L Tittlebaum M E Spencer H E Fleischman M Nebel C Gottschling D

Virus removal from wastewater using ozone Water and sewage works 1972 119 (12) 59-67

30 Xu P Janex M-L Savoye P Cockx A Lazarova V Wastewater disinfection by ozone

main parameters for process design Water Research 2002 36 (4) 1043-1055

31 Millamena O M Ozone treatment of slaughterhouse and laboratory wastewaters

Aquacultural Engineering 1991 11 23-31

32 Roux A Renovation of wastewater for direct re-use in an abattoir MSc thesis University of

Pretoria 1996

33 Proesmans P De Vil R Gerards R Vriends L Advanced treatment of industrial

wastewaters combination of biological treatment and ozonation Mededelingen-faculteit

landbouwkundige en toegepaste biologische wetenschappen 1997 62 (4) 1729-1736

34 APHA American Public Health Association Standard Methods for the Examination of

Water and Wastewater 20 ed Washington DC 1998

35 Al-Mutairi N Z Hamoda M F Al-Ghusain I A Performance-Based Characterization of

a Contact Stabilization Process for Slaughterhouse Wastewater Journal of Environmental Science

and Health Part A 2003 38 (10) 2287-2300

36 Fongsatitkul P Wareham D G Elefsiniotis P Charoensuk P Treatment of a

slaughterhouse wastewater effect of internal recycle rate on chemical oxygen demand total Kjeldahl

nitrogen and total phosphorus removal Environmental Technology 2011 32 (15) 1755-1759

37 Environmental Protection Agency Wastewater treatment manuals Primary secondary and

tertiary treatment Ardcavan Wexford Ireland 1997

38 Lovett D A Travers S M Davey K R Activated sludge treatment of abattoir

wastewater-I Influence of sludge age and feeding pattern Water Research 1984 18 (4) 429-434

39 Abbas H Seif H Moursy A Effect of hydraulic retention time on the activated sludge

system In Sixth International Water Technology Conference Alexandria Egypt 2001 pp 277-284

40 Zhang Y Wang X Hu M Li P Effect of hydraulic retention time (HRT) on the

biodegradation of trichloroethylene wastewater and anaerobic bacterial community in the UASB

reactor Applied microbiology biotechnology 2015 99 (4) 1977-87

41 Martiacutenez S B Peacuterez-Parra J Suay R Use of Ozone in Wastewater Treatment to Produce

Water Suitable for Irrigation Water Resources Management 2011 25 (9) 2109-2124

42 Gerardi M Settleability problems and loss of solids in the activated sludge process New

Jersey USA John Wiley and Sons 2002 179 p 2002

43 Paraskeva P Lambert S D Graham N J D Influence of Ozonation Conditions on the

Treatability of Secondary Effluents Ozone Science amp Engineering 1998 20 (2) 133-150

44 Bustillo-Lecompte C F Mehrvar M Quinones-Bolanos E Combined anaerobic-aerobic

and UVH2O2 processes for the treatment of synthetic slaughterhouse wastewater Environmental

Science and Health Part A Toxichazardous substances amp environmetal engineering 2013 48 (9)

1122-35

45 von Gunten U Ozonation of drinking water Part I Oxidation kinetics and product

formation Water Research 2003 37 (7) 1443-1467

46 Jin X Peldszus S Huck P M Reaction kinetics of selected micropollutants in ozonation

and advanced oxidation processes Water Research 2012 46 (19) 6519-30

47 Masten S J Davies S H R The use of ozonation to degrade organic contaminants in

wastewaters Environmental science amp technology 1994 28 (4) 180-185

48 Gray N F Ozone disinfection In Microbiology of waterborne diseases ElsevierAcademic

Press 2014 pp 599-615

49 Wu P F Mittal G S Characterization of provincial inspected slaughterhouse wastewater

in Ontario Canada Canadian biosystems engineering 2001 53 (6) 9-18

50 Finch G R Smith D W Ozone dose-response of Escherichia coli in activated sludge

effluent Water Research 1989 23 (8) 1017-1025

51 Arayan L Alisha W B Reyes Huynh T Hop Huy T Xuan Eun J Baek Han S Yang

Hong H Chang Suk Kim Antimicrobial effect of different concentrations of ozonate water in the

sanitation of water experimentally inoculated with Escherichia coli Preventive Veterinary Medicine

2017 41 (2) 84-87

52 Liberti L Notarnicola M Lopez A Advanced Treatment For Municipal Wastewater

Reuse In Agriculture III - Ozone Disinfection Ozone Science amp Engineering 2000 22 (2) 151-166

53 Mara D Cairncross S Guidelines for the safe use of wastewater and excreta in agriculture

and aquaculture In World Health Organization Geneva 1989

54 Council Directive 9883EC on the quality of water intended for human consumption O

European Union In 1998 p 42

55 Dietrich J P Loge F J Ginn T R Basagaoglu H Inactivation of particle-associated

microorganisms in wastewater disinfection modeling of ozone and chlorine reactive diffusive

transport in polydispersed suspensions Water Research 2007 41 (10) 2189-201

56 Hess S Gallert C Sensitivity of antibiotic resistant and antibiotic susceptible Escherichia

coli Enterococcus and Staphylococcus strains against ozone Water Health 2015 13 (4) 1020-8

57 Patil S Bourke P Frias J M Tiwari B K Cullen P J Inactivation of Escherichia coli

in orange juice using ozone Innovative Food Science amp Emerging Technologies 2009 10 (4) 551-

557

58 Czekalski N Imminger S Salhi E Veljkovic M Kleffel K Drissner D Hammes F

Burgmann H von Gunten U Inactivation of Antibiotic Resistant Bacteria and Resistance Genes by

Ozone From Laboratory Experiments to Full-Scale Wastewater Treatment Environmental Science amp

Technology 2016 50 (21) 11862-11871

59 Young S B Setlow P Mechanisms of Bacillus subtilis spore resistance to and killing by

aqueous ozone Applied microbiology 2004 96 (5) 1133-42

60 Venosa A D Meckes M C Opatken E J Disinfection of filtered and unfiltered

secondary effluent in two ozone contactors Environment International 1981 4 299-311

We thank Worldwide Industries Pte Ltd for financial support We also acknowledge Mr C Burt and

Mr B Gibbons for their help as well as Dr D Herrera for his comments and feedback

References

1 Janex M L Xu P Savoye P Laine J M Lazarova V In Ozonation as a wastewater

disinfection process to meet reuse regulations Proceedings of the ozone world congress 1999

International ozone association 1999 pp 81-92

2 Council Directive 91271EEC concerning urban waste-water treatment L 30 European

Commission In 1991 pp 40-52

3 Amec Foster Wheeler Environment amp Infrastructure UK Ltd I ACTeon IMDEA and

NTUA EU-level instruments on water reuse European Comission In Publications Office of the

European Union Luxembourg 2016

4 Gerbens-Leenes P W Mekonnen M M Hoekstra A Y The water footprint of poultry

pork and beef A comparative study in different countries and production systems Water Resources

and Industry 2013 1-2 25-36

5 Rami Z Water and energy use and wastewater production in a beef packing plant MSc

thesis University of Nebraska-Lincoln 2015

6 Mekonnen M M Hoekstra A Y The green blue and grey water footprint of crops and

derived crop products UNESCO-IHE Delft The Netherlands Value of Water Research Report

Series 2010

7 Mekonnen M M Hoekstra A Y A global assessment of the water fooprint of farm animal

products Ecosystems 2012 15 401-415

8 Arvanitoyannis I S Ladas D Meat waste treatment methods and potential uses

International Journal of Food Science amp Technology 2008 43 (3) 543-559

9 Padilla-Gasca E Lopez-Lopez A Gallardo-Valdez J Evaluation of Stability Factors in

the Anaerobic Treatment of Slaughterhouse Wastewater Journal of Bioremediation amp

Biodegradation 2011 02 (01)

10 Bustillo-Lecompte C F Mehrvar M Treatment of an actual slaughterhouse wastewater by

integration of biological and advanced oxidation processes Modeling optimization and cost-

effectiveness analysis Journal of Environmental Management 2016 182 651-66

11 Wu J Doan H Disinfection of recycled red-meat-processing wastewater by ozone Journal

of Chemical Technology amp Biotechnology 2005 80 (7) 828-833

12 Travers S M Lovett D A Activated sludge treatment of abattoir wastewater-II Influence

of dissolved oxygen concentration Water research 1984 18 (4) 435-439

13 Al-Mutairi N Z Al-Sharifi F A Al-Shammari S B Evaluation study of a slaughterhouse

wastewater treatment plant including contact-assisted activated sludge and DAF Desalination 2008

225 (1-3) 167-175

14 Paboacuten S L Suaacuterez Geacutelvez J H Starting-up operating a full-scale activated sludge system

for slaughterhouse wastewater Revista Ingenieriacutea e Investigacioacuten 2009 29 (2) 53-58

15 Johns M R Developments in wastewater treatment in the meat processing industry a

review Bioresource technology 1995 54 (3) 203-216

16 Hsiao T H Huang J S Huang Y I Process kinetics of an activated-sludge reactor

system treating poultry slaughterhouse wastewater Environ Technol 2012 33 (7-9) 829-35

17 Chen C K Lo S L Treatment of slaughterhouse wastewater using an activated

sludgecontact aeration process Water Science amp Technology 2003 47 (12) 285-292

18 Um M M Barraud O Kerouredan M Gaschet M Stalder T Oswald E Dagot C

Ploy M C Brugere H Bibbal D Comparison of the incidence of pathogenic and antibiotic-

resistant Escherichia coli strains in adult cattle and veal calf slaughterhouse effluents highlighted

different risks for public health Water Research 2016 88 30-8

19 Heddle J F Activated sludge treatment of slaughterhouse wastes with protein recovery

Water research 1979 13 581-584

20 Gehr R Wagner M Veerasubramanian P Payment P Disinfection efficiency of

peracetic acid UV and ozone after enhanced primary treatment of municipal wastewater Water

Research 2003 37 (19) 4573-4586

21 Gehr R Wright H UV disinfection of wastewater coagulated with ferric chloride

recalcitrance and fouling problems Water Science amp Technology 1998 38 (3) 15-23

22 Lazarova V Janex M L Fiksdal L Oberg C Barcina I Pommepuy M Advanced

wastewater disinfection technologies short and long term efficiency Water Science amp Technology

1998 38 (12) 109-117

23 Paraskeva P Graham N J D Treatment of a secondary municipal effluent by ozone UV

and microfiltration microbial reduction and effect on effluent quality Desalination 2005 186 (1-3)

47-56

24 Tripathi S Pathak V Tripathi D M Tripathi B D Application of ozone based

treatments of secondary effluents Bioresource Technology 2011 102 (3) 2481-6

25 Lazarova V Liechti P-A Savoye P Hausler R Ozone disinfection main parameters for

process design in wastewater treatment and reuse Journal of Water Reuse and Desalination 2013 3

(4) 337

26 Absi F Gamache F Gehr R Liechti P Nicell J Pilot plant investigation of ozone

disinfection of physico-chemically treatedmunicipal wastewater Ozone Water Wastewater Treatment

1993 1 (7) 33-42

27 Langlais B Legube B Beuffe H Dore M Study of the nature of the by-products formed

and the risks of toxicity when disinfecting a secondary effluent with ozone Water Science amp

Technology 1992 25 (12) 135-143

28 Nebel C Gottschling D Hutchinson R L McBride T J Taylor D M Pavoni J L

Tittlebaum M E Spencer H E Fleischman M Ozone disinfection of industrial municipal

secondary effluents Water pollution control federation 1974 45 (12) 2493-2507

29 Pavoni J L Tittlebaum M E Spencer H E Fleischman M Nebel C Gottschling D

Virus removal from wastewater using ozone Water and sewage works 1972 119 (12) 59-67

30 Xu P Janex M-L Savoye P Cockx A Lazarova V Wastewater disinfection by ozone

main parameters for process design Water Research 2002 36 (4) 1043-1055

31 Millamena O M Ozone treatment of slaughterhouse and laboratory wastewaters

Aquacultural Engineering 1991 11 23-31

32 Roux A Renovation of wastewater for direct re-use in an abattoir MSc thesis University of

Pretoria 1996

33 Proesmans P De Vil R Gerards R Vriends L Advanced treatment of industrial

wastewaters combination of biological treatment and ozonation Mededelingen-faculteit

landbouwkundige en toegepaste biologische wetenschappen 1997 62 (4) 1729-1736

34 APHA American Public Health Association Standard Methods for the Examination of

Water and Wastewater 20 ed Washington DC 1998

35 Al-Mutairi N Z Hamoda M F Al-Ghusain I A Performance-Based Characterization of

a Contact Stabilization Process for Slaughterhouse Wastewater Journal of Environmental Science

and Health Part A 2003 38 (10) 2287-2300

36 Fongsatitkul P Wareham D G Elefsiniotis P Charoensuk P Treatment of a

slaughterhouse wastewater effect of internal recycle rate on chemical oxygen demand total Kjeldahl

nitrogen and total phosphorus removal Environmental Technology 2011 32 (15) 1755-1759

37 Environmental Protection Agency Wastewater treatment manuals Primary secondary and

tertiary treatment Ardcavan Wexford Ireland 1997

38 Lovett D A Travers S M Davey K R Activated sludge treatment of abattoir

wastewater-I Influence of sludge age and feeding pattern Water Research 1984 18 (4) 429-434

39 Abbas H Seif H Moursy A Effect of hydraulic retention time on the activated sludge

system In Sixth International Water Technology Conference Alexandria Egypt 2001 pp 277-284

40 Zhang Y Wang X Hu M Li P Effect of hydraulic retention time (HRT) on the

biodegradation of trichloroethylene wastewater and anaerobic bacterial community in the UASB

reactor Applied microbiology biotechnology 2015 99 (4) 1977-87

41 Martiacutenez S B Peacuterez-Parra J Suay R Use of Ozone in Wastewater Treatment to Produce

Water Suitable for Irrigation Water Resources Management 2011 25 (9) 2109-2124

42 Gerardi M Settleability problems and loss of solids in the activated sludge process New

Jersey USA John Wiley and Sons 2002 179 p 2002

43 Paraskeva P Lambert S D Graham N J D Influence of Ozonation Conditions on the

Treatability of Secondary Effluents Ozone Science amp Engineering 1998 20 (2) 133-150

44 Bustillo-Lecompte C F Mehrvar M Quinones-Bolanos E Combined anaerobic-aerobic

and UVH2O2 processes for the treatment of synthetic slaughterhouse wastewater Environmental

Science and Health Part A Toxichazardous substances amp environmetal engineering 2013 48 (9)

1122-35

45 von Gunten U Ozonation of drinking water Part I Oxidation kinetics and product

formation Water Research 2003 37 (7) 1443-1467

46 Jin X Peldszus S Huck P M Reaction kinetics of selected micropollutants in ozonation

and advanced oxidation processes Water Research 2012 46 (19) 6519-30

47 Masten S J Davies S H R The use of ozonation to degrade organic contaminants in

wastewaters Environmental science amp technology 1994 28 (4) 180-185

48 Gray N F Ozone disinfection In Microbiology of waterborne diseases ElsevierAcademic

Press 2014 pp 599-615

49 Wu P F Mittal G S Characterization of provincial inspected slaughterhouse wastewater

in Ontario Canada Canadian biosystems engineering 2001 53 (6) 9-18

50 Finch G R Smith D W Ozone dose-response of Escherichia coli in activated sludge

effluent Water Research 1989 23 (8) 1017-1025

51 Arayan L Alisha W B Reyes Huynh T Hop Huy T Xuan Eun J Baek Han S Yang

Hong H Chang Suk Kim Antimicrobial effect of different concentrations of ozonate water in the

sanitation of water experimentally inoculated with Escherichia coli Preventive Veterinary Medicine

2017 41 (2) 84-87

52 Liberti L Notarnicola M Lopez A Advanced Treatment For Municipal Wastewater

Reuse In Agriculture III - Ozone Disinfection Ozone Science amp Engineering 2000 22 (2) 151-166

53 Mara D Cairncross S Guidelines for the safe use of wastewater and excreta in agriculture

and aquaculture In World Health Organization Geneva 1989

54 Council Directive 9883EC on the quality of water intended for human consumption O

European Union In 1998 p 42

55 Dietrich J P Loge F J Ginn T R Basagaoglu H Inactivation of particle-associated

microorganisms in wastewater disinfection modeling of ozone and chlorine reactive diffusive

transport in polydispersed suspensions Water Research 2007 41 (10) 2189-201

56 Hess S Gallert C Sensitivity of antibiotic resistant and antibiotic susceptible Escherichia

coli Enterococcus and Staphylococcus strains against ozone Water Health 2015 13 (4) 1020-8

57 Patil S Bourke P Frias J M Tiwari B K Cullen P J Inactivation of Escherichia coli

in orange juice using ozone Innovative Food Science amp Emerging Technologies 2009 10 (4) 551-

557

58 Czekalski N Imminger S Salhi E Veljkovic M Kleffel K Drissner D Hammes F

Burgmann H von Gunten U Inactivation of Antibiotic Resistant Bacteria and Resistance Genes by

Ozone From Laboratory Experiments to Full-Scale Wastewater Treatment Environmental Science amp

Technology 2016 50 (21) 11862-11871

59 Young S B Setlow P Mechanisms of Bacillus subtilis spore resistance to and killing by

aqueous ozone Applied microbiology 2004 96 (5) 1133-42

60 Venosa A D Meckes M C Opatken E J Disinfection of filtered and unfiltered

secondary effluent in two ozone contactors Environment International 1981 4 299-311

10 Bustillo-Lecompte C F Mehrvar M Treatment of an actual slaughterhouse wastewater by

integration of biological and advanced oxidation processes Modeling optimization and cost-

effectiveness analysis Journal of Environmental Management 2016 182 651-66

11 Wu J Doan H Disinfection of recycled red-meat-processing wastewater by ozone Journal

of Chemical Technology amp Biotechnology 2005 80 (7) 828-833

12 Travers S M Lovett D A Activated sludge treatment of abattoir wastewater-II Influence

of dissolved oxygen concentration Water research 1984 18 (4) 435-439

13 Al-Mutairi N Z Al-Sharifi F A Al-Shammari S B Evaluation study of a slaughterhouse

wastewater treatment plant including contact-assisted activated sludge and DAF Desalination 2008

225 (1-3) 167-175

14 Paboacuten S L Suaacuterez Geacutelvez J H Starting-up operating a full-scale activated sludge system

for slaughterhouse wastewater Revista Ingenieriacutea e Investigacioacuten 2009 29 (2) 53-58

15 Johns M R Developments in wastewater treatment in the meat processing industry a

review Bioresource technology 1995 54 (3) 203-216

16 Hsiao T H Huang J S Huang Y I Process kinetics of an activated-sludge reactor

system treating poultry slaughterhouse wastewater Environ Technol 2012 33 (7-9) 829-35

17 Chen C K Lo S L Treatment of slaughterhouse wastewater using an activated

sludgecontact aeration process Water Science amp Technology 2003 47 (12) 285-292

18 Um M M Barraud O Kerouredan M Gaschet M Stalder T Oswald E Dagot C

Ploy M C Brugere H Bibbal D Comparison of the incidence of pathogenic and antibiotic-

resistant Escherichia coli strains in adult cattle and veal calf slaughterhouse effluents highlighted

different risks for public health Water Research 2016 88 30-8

19 Heddle J F Activated sludge treatment of slaughterhouse wastes with protein recovery

Water research 1979 13 581-584

20 Gehr R Wagner M Veerasubramanian P Payment P Disinfection efficiency of

peracetic acid UV and ozone after enhanced primary treatment of municipal wastewater Water

Research 2003 37 (19) 4573-4586

21 Gehr R Wright H UV disinfection of wastewater coagulated with ferric chloride

recalcitrance and fouling problems Water Science amp Technology 1998 38 (3) 15-23

22 Lazarova V Janex M L Fiksdal L Oberg C Barcina I Pommepuy M Advanced

wastewater disinfection technologies short and long term efficiency Water Science amp Technology

1998 38 (12) 109-117

23 Paraskeva P Graham N J D Treatment of a secondary municipal effluent by ozone UV

and microfiltration microbial reduction and effect on effluent quality Desalination 2005 186 (1-3)

47-56

24 Tripathi S Pathak V Tripathi D M Tripathi B D Application of ozone based

treatments of secondary effluents Bioresource Technology 2011 102 (3) 2481-6

25 Lazarova V Liechti P-A Savoye P Hausler R Ozone disinfection main parameters for

process design in wastewater treatment and reuse Journal of Water Reuse and Desalination 2013 3

(4) 337

26 Absi F Gamache F Gehr R Liechti P Nicell J Pilot plant investigation of ozone

disinfection of physico-chemically treatedmunicipal wastewater Ozone Water Wastewater Treatment

1993 1 (7) 33-42

27 Langlais B Legube B Beuffe H Dore M Study of the nature of the by-products formed

and the risks of toxicity when disinfecting a secondary effluent with ozone Water Science amp

Technology 1992 25 (12) 135-143

28 Nebel C Gottschling D Hutchinson R L McBride T J Taylor D M Pavoni J L

Tittlebaum M E Spencer H E Fleischman M Ozone disinfection of industrial municipal

secondary effluents Water pollution control federation 1974 45 (12) 2493-2507

29 Pavoni J L Tittlebaum M E Spencer H E Fleischman M Nebel C Gottschling D

Virus removal from wastewater using ozone Water and sewage works 1972 119 (12) 59-67

30 Xu P Janex M-L Savoye P Cockx A Lazarova V Wastewater disinfection by ozone

main parameters for process design Water Research 2002 36 (4) 1043-1055

31 Millamena O M Ozone treatment of slaughterhouse and laboratory wastewaters

Aquacultural Engineering 1991 11 23-31

32 Roux A Renovation of wastewater for direct re-use in an abattoir MSc thesis University of

Pretoria 1996

33 Proesmans P De Vil R Gerards R Vriends L Advanced treatment of industrial

wastewaters combination of biological treatment and ozonation Mededelingen-faculteit

landbouwkundige en toegepaste biologische wetenschappen 1997 62 (4) 1729-1736

34 APHA American Public Health Association Standard Methods for the Examination of

Water and Wastewater 20 ed Washington DC 1998

35 Al-Mutairi N Z Hamoda M F Al-Ghusain I A Performance-Based Characterization of

a Contact Stabilization Process for Slaughterhouse Wastewater Journal of Environmental Science

and Health Part A 2003 38 (10) 2287-2300

36 Fongsatitkul P Wareham D G Elefsiniotis P Charoensuk P Treatment of a

slaughterhouse wastewater effect of internal recycle rate on chemical oxygen demand total Kjeldahl

nitrogen and total phosphorus removal Environmental Technology 2011 32 (15) 1755-1759

37 Environmental Protection Agency Wastewater treatment manuals Primary secondary and

tertiary treatment Ardcavan Wexford Ireland 1997

38 Lovett D A Travers S M Davey K R Activated sludge treatment of abattoir

wastewater-I Influence of sludge age and feeding pattern Water Research 1984 18 (4) 429-434

39 Abbas H Seif H Moursy A Effect of hydraulic retention time on the activated sludge

system In Sixth International Water Technology Conference Alexandria Egypt 2001 pp 277-284

40 Zhang Y Wang X Hu M Li P Effect of hydraulic retention time (HRT) on the

biodegradation of trichloroethylene wastewater and anaerobic bacterial community in the UASB

reactor Applied microbiology biotechnology 2015 99 (4) 1977-87

41 Martiacutenez S B Peacuterez-Parra J Suay R Use of Ozone in Wastewater Treatment to Produce

Water Suitable for Irrigation Water Resources Management 2011 25 (9) 2109-2124

42 Gerardi M Settleability problems and loss of solids in the activated sludge process New

Jersey USA John Wiley and Sons 2002 179 p 2002

43 Paraskeva P Lambert S D Graham N J D Influence of Ozonation Conditions on the

Treatability of Secondary Effluents Ozone Science amp Engineering 1998 20 (2) 133-150

44 Bustillo-Lecompte C F Mehrvar M Quinones-Bolanos E Combined anaerobic-aerobic

and UVH2O2 processes for the treatment of synthetic slaughterhouse wastewater Environmental

Science and Health Part A Toxichazardous substances amp environmetal engineering 2013 48 (9)

1122-35

45 von Gunten U Ozonation of drinking water Part I Oxidation kinetics and product

formation Water Research 2003 37 (7) 1443-1467

46 Jin X Peldszus S Huck P M Reaction kinetics of selected micropollutants in ozonation

and advanced oxidation processes Water Research 2012 46 (19) 6519-30

47 Masten S J Davies S H R The use of ozonation to degrade organic contaminants in

wastewaters Environmental science amp technology 1994 28 (4) 180-185

48 Gray N F Ozone disinfection In Microbiology of waterborne diseases ElsevierAcademic

Press 2014 pp 599-615

49 Wu P F Mittal G S Characterization of provincial inspected slaughterhouse wastewater

in Ontario Canada Canadian biosystems engineering 2001 53 (6) 9-18

50 Finch G R Smith D W Ozone dose-response of Escherichia coli in activated sludge

effluent Water Research 1989 23 (8) 1017-1025

51 Arayan L Alisha W B Reyes Huynh T Hop Huy T Xuan Eun J Baek Han S Yang

Hong H Chang Suk Kim Antimicrobial effect of different concentrations of ozonate water in the

sanitation of water experimentally inoculated with Escherichia coli Preventive Veterinary Medicine

2017 41 (2) 84-87

52 Liberti L Notarnicola M Lopez A Advanced Treatment For Municipal Wastewater

Reuse In Agriculture III - Ozone Disinfection Ozone Science amp Engineering 2000 22 (2) 151-166

53 Mara D Cairncross S Guidelines for the safe use of wastewater and excreta in agriculture

and aquaculture In World Health Organization Geneva 1989

54 Council Directive 9883EC on the quality of water intended for human consumption O

European Union In 1998 p 42

55 Dietrich J P Loge F J Ginn T R Basagaoglu H Inactivation of particle-associated

microorganisms in wastewater disinfection modeling of ozone and chlorine reactive diffusive

transport in polydispersed suspensions Water Research 2007 41 (10) 2189-201

56 Hess S Gallert C Sensitivity of antibiotic resistant and antibiotic susceptible Escherichia

coli Enterococcus and Staphylococcus strains against ozone Water Health 2015 13 (4) 1020-8

57 Patil S Bourke P Frias J M Tiwari B K Cullen P J Inactivation of Escherichia coli

in orange juice using ozone Innovative Food Science amp Emerging Technologies 2009 10 (4) 551-

557

58 Czekalski N Imminger S Salhi E Veljkovic M Kleffel K Drissner D Hammes F

Burgmann H von Gunten U Inactivation of Antibiotic Resistant Bacteria and Resistance Genes by

Ozone From Laboratory Experiments to Full-Scale Wastewater Treatment Environmental Science amp

Technology 2016 50 (21) 11862-11871

59 Young S B Setlow P Mechanisms of Bacillus subtilis spore resistance to and killing by

aqueous ozone Applied microbiology 2004 96 (5) 1133-42

60 Venosa A D Meckes M C Opatken E J Disinfection of filtered and unfiltered

secondary effluent in two ozone contactors Environment International 1981 4 299-311

21 Gehr R Wright H UV disinfection of wastewater coagulated with ferric chloride

recalcitrance and fouling problems Water Science amp Technology 1998 38 (3) 15-23

22 Lazarova V Janex M L Fiksdal L Oberg C Barcina I Pommepuy M Advanced

wastewater disinfection technologies short and long term efficiency Water Science amp Technology

1998 38 (12) 109-117

23 Paraskeva P Graham N J D Treatment of a secondary municipal effluent by ozone UV

and microfiltration microbial reduction and effect on effluent quality Desalination 2005 186 (1-3)

47-56

24 Tripathi S Pathak V Tripathi D M Tripathi B D Application of ozone based

treatments of secondary effluents Bioresource Technology 2011 102 (3) 2481-6

25 Lazarova V Liechti P-A Savoye P Hausler R Ozone disinfection main parameters for

process design in wastewater treatment and reuse Journal of Water Reuse and Desalination 2013 3

(4) 337

26 Absi F Gamache F Gehr R Liechti P Nicell J Pilot plant investigation of ozone

disinfection of physico-chemically treatedmunicipal wastewater Ozone Water Wastewater Treatment

1993 1 (7) 33-42

27 Langlais B Legube B Beuffe H Dore M Study of the nature of the by-products formed

and the risks of toxicity when disinfecting a secondary effluent with ozone Water Science amp

Technology 1992 25 (12) 135-143

28 Nebel C Gottschling D Hutchinson R L McBride T J Taylor D M Pavoni J L

Tittlebaum M E Spencer H E Fleischman M Ozone disinfection of industrial municipal

secondary effluents Water pollution control federation 1974 45 (12) 2493-2507

29 Pavoni J L Tittlebaum M E Spencer H E Fleischman M Nebel C Gottschling D

Virus removal from wastewater using ozone Water and sewage works 1972 119 (12) 59-67

30 Xu P Janex M-L Savoye P Cockx A Lazarova V Wastewater disinfection by ozone

main parameters for process design Water Research 2002 36 (4) 1043-1055

31 Millamena O M Ozone treatment of slaughterhouse and laboratory wastewaters

Aquacultural Engineering 1991 11 23-31

32 Roux A Renovation of wastewater for direct re-use in an abattoir MSc thesis University of

Pretoria 1996

33 Proesmans P De Vil R Gerards R Vriends L Advanced treatment of industrial

wastewaters combination of biological treatment and ozonation Mededelingen-faculteit

landbouwkundige en toegepaste biologische wetenschappen 1997 62 (4) 1729-1736

34 APHA American Public Health Association Standard Methods for the Examination of

Water and Wastewater 20 ed Washington DC 1998

35 Al-Mutairi N Z Hamoda M F Al-Ghusain I A Performance-Based Characterization of

a Contact Stabilization Process for Slaughterhouse Wastewater Journal of Environmental Science

and Health Part A 2003 38 (10) 2287-2300

36 Fongsatitkul P Wareham D G Elefsiniotis P Charoensuk P Treatment of a

slaughterhouse wastewater effect of internal recycle rate on chemical oxygen demand total Kjeldahl

nitrogen and total phosphorus removal Environmental Technology 2011 32 (15) 1755-1759

37 Environmental Protection Agency Wastewater treatment manuals Primary secondary and

tertiary treatment Ardcavan Wexford Ireland 1997

38 Lovett D A Travers S M Davey K R Activated sludge treatment of abattoir

wastewater-I Influence of sludge age and feeding pattern Water Research 1984 18 (4) 429-434

39 Abbas H Seif H Moursy A Effect of hydraulic retention time on the activated sludge

system In Sixth International Water Technology Conference Alexandria Egypt 2001 pp 277-284

40 Zhang Y Wang X Hu M Li P Effect of hydraulic retention time (HRT) on the

biodegradation of trichloroethylene wastewater and anaerobic bacterial community in the UASB

reactor Applied microbiology biotechnology 2015 99 (4) 1977-87

41 Martiacutenez S B Peacuterez-Parra J Suay R Use of Ozone in Wastewater Treatment to Produce

Water Suitable for Irrigation Water Resources Management 2011 25 (9) 2109-2124

42 Gerardi M Settleability problems and loss of solids in the activated sludge process New

Jersey USA John Wiley and Sons 2002 179 p 2002

43 Paraskeva P Lambert S D Graham N J D Influence of Ozonation Conditions on the

Treatability of Secondary Effluents Ozone Science amp Engineering 1998 20 (2) 133-150

44 Bustillo-Lecompte C F Mehrvar M Quinones-Bolanos E Combined anaerobic-aerobic

and UVH2O2 processes for the treatment of synthetic slaughterhouse wastewater Environmental

Science and Health Part A Toxichazardous substances amp environmetal engineering 2013 48 (9)

1122-35

45 von Gunten U Ozonation of drinking water Part I Oxidation kinetics and product

formation Water Research 2003 37 (7) 1443-1467

46 Jin X Peldszus S Huck P M Reaction kinetics of selected micropollutants in ozonation

and advanced oxidation processes Water Research 2012 46 (19) 6519-30

47 Masten S J Davies S H R The use of ozonation to degrade organic contaminants in

wastewaters Environmental science amp technology 1994 28 (4) 180-185

48 Gray N F Ozone disinfection In Microbiology of waterborne diseases ElsevierAcademic

Press 2014 pp 599-615

49 Wu P F Mittal G S Characterization of provincial inspected slaughterhouse wastewater

in Ontario Canada Canadian biosystems engineering 2001 53 (6) 9-18

50 Finch G R Smith D W Ozone dose-response of Escherichia coli in activated sludge

effluent Water Research 1989 23 (8) 1017-1025

51 Arayan L Alisha W B Reyes Huynh T Hop Huy T Xuan Eun J Baek Han S Yang

Hong H Chang Suk Kim Antimicrobial effect of different concentrations of ozonate water in the

sanitation of water experimentally inoculated with Escherichia coli Preventive Veterinary Medicine

2017 41 (2) 84-87

52 Liberti L Notarnicola M Lopez A Advanced Treatment For Municipal Wastewater

Reuse In Agriculture III - Ozone Disinfection Ozone Science amp Engineering 2000 22 (2) 151-166

53 Mara D Cairncross S Guidelines for the safe use of wastewater and excreta in agriculture

and aquaculture In World Health Organization Geneva 1989

54 Council Directive 9883EC on the quality of water intended for human consumption O

European Union In 1998 p 42

55 Dietrich J P Loge F J Ginn T R Basagaoglu H Inactivation of particle-associated

microorganisms in wastewater disinfection modeling of ozone and chlorine reactive diffusive

transport in polydispersed suspensions Water Research 2007 41 (10) 2189-201

56 Hess S Gallert C Sensitivity of antibiotic resistant and antibiotic susceptible Escherichia

coli Enterococcus and Staphylococcus strains against ozone Water Health 2015 13 (4) 1020-8

57 Patil S Bourke P Frias J M Tiwari B K Cullen P J Inactivation of Escherichia coli

in orange juice using ozone Innovative Food Science amp Emerging Technologies 2009 10 (4) 551-

557

58 Czekalski N Imminger S Salhi E Veljkovic M Kleffel K Drissner D Hammes F

Burgmann H von Gunten U Inactivation of Antibiotic Resistant Bacteria and Resistance Genes by

Ozone From Laboratory Experiments to Full-Scale Wastewater Treatment Environmental Science amp

Technology 2016 50 (21) 11862-11871

59 Young S B Setlow P Mechanisms of Bacillus subtilis spore resistance to and killing by

aqueous ozone Applied microbiology 2004 96 (5) 1133-42

60 Venosa A D Meckes M C Opatken E J Disinfection of filtered and unfiltered

secondary effluent in two ozone contactors Environment International 1981 4 299-311

32 Roux A Renovation of wastewater for direct re-use in an abattoir MSc thesis University of

Pretoria 1996

33 Proesmans P De Vil R Gerards R Vriends L Advanced treatment of industrial

wastewaters combination of biological treatment and ozonation Mededelingen-faculteit

landbouwkundige en toegepaste biologische wetenschappen 1997 62 (4) 1729-1736

34 APHA American Public Health Association Standard Methods for the Examination of

Water and Wastewater 20 ed Washington DC 1998

35 Al-Mutairi N Z Hamoda M F Al-Ghusain I A Performance-Based Characterization of

a Contact Stabilization Process for Slaughterhouse Wastewater Journal of Environmental Science

and Health Part A 2003 38 (10) 2287-2300

36 Fongsatitkul P Wareham D G Elefsiniotis P Charoensuk P Treatment of a

slaughterhouse wastewater effect of internal recycle rate on chemical oxygen demand total Kjeldahl

nitrogen and total phosphorus removal Environmental Technology 2011 32 (15) 1755-1759

37 Environmental Protection Agency Wastewater treatment manuals Primary secondary and

tertiary treatment Ardcavan Wexford Ireland 1997

38 Lovett D A Travers S M Davey K R Activated sludge treatment of abattoir

wastewater-I Influence of sludge age and feeding pattern Water Research 1984 18 (4) 429-434

39 Abbas H Seif H Moursy A Effect of hydraulic retention time on the activated sludge

system In Sixth International Water Technology Conference Alexandria Egypt 2001 pp 277-284

40 Zhang Y Wang X Hu M Li P Effect of hydraulic retention time (HRT) on the

biodegradation of trichloroethylene wastewater and anaerobic bacterial community in the UASB

reactor Applied microbiology biotechnology 2015 99 (4) 1977-87

41 Martiacutenez S B Peacuterez-Parra J Suay R Use of Ozone in Wastewater Treatment to Produce

Water Suitable for Irrigation Water Resources Management 2011 25 (9) 2109-2124

42 Gerardi M Settleability problems and loss of solids in the activated sludge process New

Jersey USA John Wiley and Sons 2002 179 p 2002

43 Paraskeva P Lambert S D Graham N J D Influence of Ozonation Conditions on the

Treatability of Secondary Effluents Ozone Science amp Engineering 1998 20 (2) 133-150

44 Bustillo-Lecompte C F Mehrvar M Quinones-Bolanos E Combined anaerobic-aerobic

and UVH2O2 processes for the treatment of synthetic slaughterhouse wastewater Environmental

Science and Health Part A Toxichazardous substances amp environmetal engineering 2013 48 (9)

1122-35

45 von Gunten U Ozonation of drinking water Part I Oxidation kinetics and product

formation Water Research 2003 37 (7) 1443-1467

46 Jin X Peldszus S Huck P M Reaction kinetics of selected micropollutants in ozonation

and advanced oxidation processes Water Research 2012 46 (19) 6519-30

47 Masten S J Davies S H R The use of ozonation to degrade organic contaminants in

wastewaters Environmental science amp technology 1994 28 (4) 180-185

48 Gray N F Ozone disinfection In Microbiology of waterborne diseases ElsevierAcademic

Press 2014 pp 599-615

49 Wu P F Mittal G S Characterization of provincial inspected slaughterhouse wastewater

in Ontario Canada Canadian biosystems engineering 2001 53 (6) 9-18

50 Finch G R Smith D W Ozone dose-response of Escherichia coli in activated sludge

effluent Water Research 1989 23 (8) 1017-1025

51 Arayan L Alisha W B Reyes Huynh T Hop Huy T Xuan Eun J Baek Han S Yang

Hong H Chang Suk Kim Antimicrobial effect of different concentrations of ozonate water in the

sanitation of water experimentally inoculated with Escherichia coli Preventive Veterinary Medicine

2017 41 (2) 84-87

52 Liberti L Notarnicola M Lopez A Advanced Treatment For Municipal Wastewater

Reuse In Agriculture III - Ozone Disinfection Ozone Science amp Engineering 2000 22 (2) 151-166

53 Mara D Cairncross S Guidelines for the safe use of wastewater and excreta in agriculture

and aquaculture In World Health Organization Geneva 1989

54 Council Directive 9883EC on the quality of water intended for human consumption O

European Union In 1998 p 42

55 Dietrich J P Loge F J Ginn T R Basagaoglu H Inactivation of particle-associated

microorganisms in wastewater disinfection modeling of ozone and chlorine reactive diffusive

transport in polydispersed suspensions Water Research 2007 41 (10) 2189-201

56 Hess S Gallert C Sensitivity of antibiotic resistant and antibiotic susceptible Escherichia

coli Enterococcus and Staphylococcus strains against ozone Water Health 2015 13 (4) 1020-8

57 Patil S Bourke P Frias J M Tiwari B K Cullen P J Inactivation of Escherichia coli

in orange juice using ozone Innovative Food Science amp Emerging Technologies 2009 10 (4) 551-

557

58 Czekalski N Imminger S Salhi E Veljkovic M Kleffel K Drissner D Hammes F

Burgmann H von Gunten U Inactivation of Antibiotic Resistant Bacteria and Resistance Genes by

Ozone From Laboratory Experiments to Full-Scale Wastewater Treatment Environmental Science amp

Technology 2016 50 (21) 11862-11871

59 Young S B Setlow P Mechanisms of Bacillus subtilis spore resistance to and killing by

aqueous ozone Applied microbiology 2004 96 (5) 1133-42

60 Venosa A D Meckes M C Opatken E J Disinfection of filtered and unfiltered

secondary effluent in two ozone contactors Environment International 1981 4 299-311

44 Bustillo-Lecompte C F Mehrvar M Quinones-Bolanos E Combined anaerobic-aerobic

and UVH2O2 processes for the treatment of synthetic slaughterhouse wastewater Environmental

Science and Health Part A Toxichazardous substances amp environmetal engineering 2013 48 (9)

1122-35

45 von Gunten U Ozonation of drinking water Part I Oxidation kinetics and product

formation Water Research 2003 37 (7) 1443-1467

46 Jin X Peldszus S Huck P M Reaction kinetics of selected micropollutants in ozonation

and advanced oxidation processes Water Research 2012 46 (19) 6519-30

47 Masten S J Davies S H R The use of ozonation to degrade organic contaminants in

wastewaters Environmental science amp technology 1994 28 (4) 180-185

48 Gray N F Ozone disinfection In Microbiology of waterborne diseases ElsevierAcademic

Press 2014 pp 599-615

49 Wu P F Mittal G S Characterization of provincial inspected slaughterhouse wastewater

in Ontario Canada Canadian biosystems engineering 2001 53 (6) 9-18

50 Finch G R Smith D W Ozone dose-response of Escherichia coli in activated sludge

effluent Water Research 1989 23 (8) 1017-1025

51 Arayan L Alisha W B Reyes Huynh T Hop Huy T Xuan Eun J Baek Han S Yang

Hong H Chang Suk Kim Antimicrobial effect of different concentrations of ozonate water in the

sanitation of water experimentally inoculated with Escherichia coli Preventive Veterinary Medicine

2017 41 (2) 84-87

52 Liberti L Notarnicola M Lopez A Advanced Treatment For Municipal Wastewater

Reuse In Agriculture III - Ozone Disinfection Ozone Science amp Engineering 2000 22 (2) 151-166

53 Mara D Cairncross S Guidelines for the safe use of wastewater and excreta in agriculture

and aquaculture In World Health Organization Geneva 1989

54 Council Directive 9883EC on the quality of water intended for human consumption O

European Union In 1998 p 42

55 Dietrich J P Loge F J Ginn T R Basagaoglu H Inactivation of particle-associated

microorganisms in wastewater disinfection modeling of ozone and chlorine reactive diffusive

transport in polydispersed suspensions Water Research 2007 41 (10) 2189-201

56 Hess S Gallert C Sensitivity of antibiotic resistant and antibiotic susceptible Escherichia

coli Enterococcus and Staphylococcus strains against ozone Water Health 2015 13 (4) 1020-8

57 Patil S Bourke P Frias J M Tiwari B K Cullen P J Inactivation of Escherichia coli

in orange juice using ozone Innovative Food Science amp Emerging Technologies 2009 10 (4) 551-

557

58 Czekalski N Imminger S Salhi E Veljkovic M Kleffel K Drissner D Hammes F

Burgmann H von Gunten U Inactivation of Antibiotic Resistant Bacteria and Resistance Genes by

Ozone From Laboratory Experiments to Full-Scale Wastewater Treatment Environmental Science amp

Technology 2016 50 (21) 11862-11871

59 Young S B Setlow P Mechanisms of Bacillus subtilis spore resistance to and killing by

aqueous ozone Applied microbiology 2004 96 (5) 1133-42

60 Venosa A D Meckes M C Opatken E J Disinfection of filtered and unfiltered

secondary effluent in two ozone contactors Environment International 1981 4 299-311

55 Dietrich J P Loge F J Ginn T R Basagaoglu H Inactivation of particle-associated

microorganisms in wastewater disinfection modeling of ozone and chlorine reactive diffusive

transport in polydispersed suspensions Water Research 2007 41 (10) 2189-201

56 Hess S Gallert C Sensitivity of antibiotic resistant and antibiotic susceptible Escherichia

coli Enterococcus and Staphylococcus strains against ozone Water Health 2015 13 (4) 1020-8

57 Patil S Bourke P Frias J M Tiwari B K Cullen P J Inactivation of Escherichia coli

in orange juice using ozone Innovative Food Science amp Emerging Technologies 2009 10 (4) 551-

557

58 Czekalski N Imminger S Salhi E Veljkovic M Kleffel K Drissner D Hammes F

Burgmann H von Gunten U Inactivation of Antibiotic Resistant Bacteria and Resistance Genes by

Ozone From Laboratory Experiments to Full-Scale Wastewater Treatment Environmental Science amp

Technology 2016 50 (21) 11862-11871

59 Young S B Setlow P Mechanisms of Bacillus subtilis spore resistance to and killing by

aqueous ozone Applied microbiology 2004 96 (5) 1133-42

60 Venosa A D Meckes M C Opatken E J Disinfection of filtered and unfiltered

secondary effluent in two ozone contactors Environment International 1981 4 299-311