EFFECT OF OZONIZATION ON COD AND BODs VALUESOF WASTEWATER FROM DETERGENT MANUFACTURER

Adi Mulyanto*} and Neni Sintawardani**}

*) Directorate for the Human Settlement and Environmental Technology, Agency for theAssessment and Application of Technology (BPP Teknologi).

**) Division of Environmental Physics, Research and Development Centre for AppliedPhysics, Indonesian Institute of Sciences

ABSTRACT

The aim of this experiments were to examine the effect ofozonizotion on COD and BOD) value of wastewater from a detergentmanufacturer and to putforward the efficiency of COD and BOD)removal as a function of the ozonization. It has been known thatthe detergent industry produces wastewater with high concentrationof both COD and BODr The observation showed that theozonization alone was not a practical approachfor COD and BOD <

removal. However, the role of ozonization as a preliminary processbefore the biological one seems to be significant.

INTISARI

Tujuan percobaan tni adalah untuk mengamati pengaruhozonisasi pada nilai BOD) (Kebutuhan Oksigen Biologis selama5 hari) dan COD (Kebutuhan Oksigen Kimia) dari air limbahindustri det erjen yang diketahui mengandung polutan organikyang cukup linggi. Selain itu juga diamati lebih jauh efisiensipengurangan kandungan BOD) dan COD seb agai fungsi dariproses ozonisasi. Hasil percobaan menunjukkan bahwa prosesozo n as i b uka nl a h faktor yang b erp eng aru h nyata padaI'en~urangan konsentrasi rOD dan BOD). tet api ozonisasisebagai proses awal sebelum pengolahan limb ah secara biologisberpengaruh nyata pada kinerja penguraian bahan organik yangterkandung di dalam limbah cair.

Keywords: Soap Lyes; untreated wastewater; ozone; ozonization;('OJ); BOD,; removal; biodegradable; biological process.

INTRODUCTION

A common property of all wastewaters containmgorganic matter is their pronounce affinity for oxygen. Thiscondition varies according to the nature and quantity ofoxidizable materials. Therefore, to assess their strength theoxygen consuming characteristics of wastewater are usuallyused such as COD and BODs' The COD is the amount ofoxygen utilized in the oxidation of organic matters bypotassium dichromate under standard conditions. Whereas,the BODs is the amount of dissolved oxygen utilized in theoxidation of organic matters by microbiological action whena sample of wastewater is incubated under standard

JKTI, Vol. 8, No. 1-2, Desember 1998

conditions of time and temperature (Nicoll, 1988) TheCOO, BODs' organic carbon, and organic matters from aspecific sample source can be related to each other (APHA,AWWA, WEF, 1992).

Livke et a1. (1972, cited in Rice and Browni ng, 1980)ozonized the wastewaters from the caprolactam synthesisat two different Russian chemical plants. Ozonization wasconducted after biological treatment. Following theozonization, the ozonized effluents were sent to thebiological ponds prior to reuse as cooling water. The resultof ozonization (ozone dosage 15 to 25 ppm) indicated thatthe BODs values increased as the COD values decreased,and the ratios of BODs: COD changed from 0.1 to 0.5.This phenomena showed that the increasing of BODs valueis a result of oxidative degradation of the resins to simplercompounds.

Davis et a1. (1976, cited in Rice and Browning, 1980)investigated an ozonization of wastewaters from theproduction of several alkyl amines employing a submergedturbine contactor. The result showed that during the firsttwo hours of ozonization, the residual COD of isobutyl aminewastewater increased. However, after an additional two hoursozonization, the COD then dropped to about 33% of theoriginal content. The concentration of ozone applied was 39mg/l-min.

Ozonization of wastewater generated from a syntheticorganic chemicals plant manufacturing chelating agents wasconducted by the same authors. The result identified thatozonization had little effect on the COD of the wastewaterbefore biological treatment, but the COD decreasedsignificantly after biological treatment. However, ozonizationof dissolved organic compounds can improve theirbiodegradability (van Leeuwen, 1987; Harrington and DiGiano, 1989~ Kruithof, 1989~ and DeWaters and DiGiano,1990). Another ozonization was done by Davis et al. (1976,cited in Rice and Browning, 1980) on wastewater generatedfrom an organic chemicals plant producing organic dyes andresins. The effect of ozonization on BODs was a linearlyincreased (up to 2,900%) with ozone doses of up to 200 ppm.Ozonization of effluents from the dye industries resulted ineighty per cent of colour removal, but the removal of CODreached only 20% using an ozone dosage of2S g/m3. Anotherozonization was petformed on used metal-containing dyes.The result indicated that the colour removal was

37

roximately 80-90% for a COD removal limited toapproximately 10% (Le Tareau and Rovel, 1982).

Wastewater from detergent industries or from synthetictenside manufacturer is known to contain high concentration- organic pollutants which reflected their components in

• IT products. Generally, this kind of wastewater containsorganic materials like fat and oil components, tensidesubstances, stabilizing agents (phosphate, nitriloacetate,CDTA) and other substances (Poppinghaus et al., 1994).

The aims of this experiments were to examine the effectof ozonization on COD and BOD 5 values of wastewater froma detergent manufacturer and to evaluate the efficiency ofCOD and BOD, removal as a function of the ozonization.

MATERIALS AND METHODS

I. Sampling

Samples were provided by a detergent manufacturer andconsisted of soap lyes (S sample) and untreated wastewatercW sample). These samples were stored in a cold room forthree days prior to ozonization and analysis of the COD andBOD,.

2. Ozonization

Figure 1. illustrates a schematic design of the laboratorystudy plant. Ozone (03) was generated from pressurized dryair by a laboratory corona discharge ozonator. The details ofthe ozonization was described elsewhere (Mulyanto, 1995)

The ozone dosages was the function of the ozonizationtime with a constant gas flow rate of 1.36 lImin ..

LJ FLOWMETEROZONE GAS

CONTACT SCRUBBERCOLUMN

Figure 1. Schematic design of the laboratory study plant

3. COD Analysis

The analysis of COD was carried out using preparedreagent vials obtained from Hach. Two kinds of reagent wereused, namely low range (0-150 mg CODlLfor Wtype sample)and high range (0-1500 mg CODIL for S type sample)reagent. The reagent vials contained a prepared mixture of

38

sulfuric acid. mercuric sulfate, chromic acid, silver sulfate.and water. Two millilitres of diluted samples (100 times forraw and 50 times for ozonized W type. 200 times for rawand ozonized S type samples) were pipetted into the vials.The vials were then heated on the heating block (Hach CODReactor, USA) for 2 hours at 150°C. Following digestion,the vials were allowed to cool to room temperature and theCOD was measured using a spectrophotometer (Hach DR!2000). The COD value was displayed on the screen of thespectrophotometer in mg/I (ppm).

The principle of the reaction can be illustrated as follows(Nicoll, 1988):

4. BOD5 Analysis

The analysis of BOD, was conducted for the wastewatersample before and after ozonization. Both types of sample(Wand S) were expected to have a high BOD5 value.Therefore, dilution of 500 and 13,333 times were appliedrespecti vely.

The BOD, test requires the measurement of dissolvedoxygen of sample before and after incubation for 5 days at 20°Cand is calculated from the difference between the twomeasurements. The test was conducted in an overflowingairtight BOD bottle of the specified size, with the flared mouthfor overflow of sample. This provided a water-seal in orderto prevent drawing air into the dilution bottle duringincubation. The BOD incubation was carried out in the darkto prevent possibility of photosynthetic production of DO(APHA, AWWA, WEF, 1992)

The dilution water was prepared by the aeration of potablewater with pressurized air for 2 days in order to real ease thechlorine content and to achieve the DO saturation. Thedilution water contained of phosphate buffer (potassium di-hydrogen phosphate, di-potassium hydrogen phosphate, di-sodium hydrogen phosphate), ammonium chloride.magnesium sulfate, calcium chloride, and ferric chloridesolution. The quality of dilution water was checked in orderto know the DO uptake in 5 days at 20°C.

The analysis of DO was done by using the azidemodification method. Before titrating with sodium thiosulfateand adding starch as an indicator, manganous sulfate solutionwas added to the sample followed by alkali-iodide-azidereagent. The alkali-iodide-azide reagent. consisted of sodiumhydroxide, potassium iodide, and sodium azide. To dissolvethe floc which might develop concentrated sulfuric acid wasadded. For the titration of a 200 ml sample, 1 ml 0.025 Msodium thiosulfate = 1 mg DOll.

RESULTS AND DISCUSSION

Figures 2. and 3. illustrate the effect of ozonization onCOD and BOD; values of Soap Lyes (S samples). The initial

JKTI, Vol. 8, No. 1-2, Desember 1998

concentration of COD and BODs values were consideriablyhigh, namely 155,000 ppm and 85,200 ppm respectively. Itwas obtained that the concentration of COD become slightlyhigher than the initial sample after ozonatization usingozone dosage of 1 gll. This was the result of oxidativedegradation of the organic matter to simpler compounds.Using more than 3 gll ozon dosage, the COD-concentrationof S-wastewater decreased significantly from 154 gll to 144gll. In general, the influence of ozone dosage on theconcentration of COD was significantly decreased.

The change in concentration of BOD s showed differenttrend than that of the COD. It decreased from 85.2 gll to642 gll using ozone-concentration lass than I gll, and thantend slightly to increase on higher ozone dosages.

160 -

158 - •156

154

152

150

148

146

144

CIoo

142 ---.------- ---..- ··• __·__· .h •. l

o 2 4 6 8Ozone Dosage [g/l]

10

Figure 2. Influence of ozone dosage on the concentration of CODin Soap Lyes

90 .•80 • •- .....•70 • • • •60 •CI50

d' 400a:J 30 •

2010

0

0 5 10

Ozone Dosage [g/l]

Figure 3. Influence of ozone dosage on the concentration ofBOD5ill Soap Lyes

The maximum COD removal was 7.5 % by using ozonedosage of 7 gll (Figure 4.). The low efficiency of CODremoval may be due to incomplete oxidation of the detergentcontained wastewater sample into carbon dioxide by ozone.

In some cases it was discovered that the BODs level ofthe ozonized S-wastewater tend to increase slightly withincreasing the ozone dosages. This phenomenon is attributed

JKTI, Vol. 8, No. 1-2, Desember 1998

to the fact that ozone can oxidise non-biodegradable materialto biodegradable material which then exerts additional oxygendemand. The maximum BODs removal was 25.3% by usingozone dosage of 0.671 gll (Figure 5). Figure 6 showed thatthe ratios of BODs to COD tend to increase with increasingthe ozone dosage.

Ozone Dosage [g/l]

10

8

~ 60

(ij4 ->0 ••E~ 2

et:CI 00 •o 0 2 4 6 8 10

-2 •-4

Figure 4. Influence of ozone dosage on COD-removal of SoapLyes

30

~ 25 •0

(ij 20>0 15ECJ)

10et:d' • •0a:J o.

0 2 4 6 8 10

Ozone Dosage [9/1]

Figure 5. Influence of ozone dosage on the BOD, Removal ofSoap Lyes

0.6 • •CI 0_5 * • •0 • • •U 04 •a

0.30a:J0.2

0:;:; 0.1raet:

0 -- ---- --_ ...._---- .._--_._ ...0 2 4 6 8 10

Ozone Dosage [ g/l ]

Figure 6. Influence of ozone dosage on the BOD, ICOD-ratio ofSoap Lyes

The effect of ozonization on COD and BOD, values of

39

entreated Wastewater (W samples) can be seen in Figures 7d 8. The result of original COD and BOD! values were

6_3gIl and 2.9 g/l respectively. Ozonization caused the COD-concentration to decrease to 5.9 g/l in average. On the contrarythe BODs tend to increase than the initial BODs-concentrationby using ozone dosage of more than 0.3 g/l.

The maximum removal of COD in W-wastewater was_9 % by 0.5 g/l ozone dosage (Figure 9). In average the

ozonization caused 7 % COD-removal. Whereas, themaximum efficiency of BOD! removal was 21% by usingozone dosage less than 0.1 g/l, but the BODs removaldecreased drastically to values of lower than 0 % at higherozone dosage (Figure 10). This phenomenon could be causedby the formation of biodegradable organic materials containedtn the W-type wastewater. Through ozonization at ozonedosage of more than 0.1 g/l, the non-biodegradable COD-content in wastewater was oxidized to biodegradable materialsand increased the BOD5 -concentration. Figure 11 showedthose tendencies on the BOD/COD-ratios

On ozonization at the highest ozone dosage level (9.636g/l and 0.616 g/l), the residual ozone trapped in the Drexelbottle was 3.7 ppm and 21.3 ppm for Sand W samplesrespectively. This investigation gives evidence of the existenceof an ozone refractory compounds in wastewater. Performanceof organic material removal between S and W wastewaterwas different. It was shown that more components in Wsamples were easier to be degraded rather than thosecontained in the S samples.

6.2:::::::OJ 6.1Cloo

6 j

I5.9 i •l5.8

••

._-------+,----200 400 600

Ozone Dosage [ ppm 1o 800

Figure 7. Influence of ozone dosage on the concentration of CODin Untreated Wastewater (W-Wastewater)

3. • •l- •2.5•

~2

1.5d0III

0.5Q

0 200 400 600Ozone Dosage [ppm]

800

Figure 8. Influence of ozone dosage on the concentration of BODsin Untreated Wastewater (W-Wastewater)

40

8 - •~o

~ 5oE 4~ 3Cl 2oU 1

0+o 600 800200 400

Ozone Dosage [ ppm ]

Figure 9. Influence of ozone dosage on the COD removal ofUntreated Wastewater

25 -20 •~0

iii 15>0 10Ec1Ic:: 5d0 o.III

0 200 • 800-5 -Ozone Dosage [ ppm ]

Figure 10. Influence of ozone dosage on the BOD\ removal ofUntreated Wastewater

0.6

c 0.5 • • ~0 .... •U 04a •0 0.3III

00.2

:;:;ra 0.1c::

00 200 400 600 800

Ozone Dosage [ ppm ]

Figure 11. Influence of ozone dosage on the BOD/BOD-ratio ofWastewater

JKTI, Vol. 8, No. 1-2, Desember 1998

CONCLUSION

The effect of ozonization on COD values was insignificantfor treating wastewater from detergent industries. It wasobtained that highest COD removal was only 8 % even whenhigh ozone dosage (7.29 gll) was applied. With certain ozonedosages, the ozonized S- and W-wastewater had lower CODvalue than the un-ozonized one. In the same manner,ozonization caused a decrease in BOD, value by ozonizationof the S-wastewater. However, the BODs tend to remainconstant as the initial concentration or slightly higher byozonization on the W-wastewater.

In summary, ozonization of the wastewater alone from adetergent manufacturer was not a practical approach for CODand BODs removal. However, the application of ozone beforethe biological process is necessary to be taken intoconsideration in view of the phenomenon that ozone hascapability to oxidize non-biodegradable material to becomebiodegradable one. Therefore, continuation of research anda feasibility study are recommended before the manufacturerbegin applying the treatment process.

REFERENCES

APHA, AWWA, and WEF. (J992). Standard Methods forthe Examination of Water and Wastewater. Baltimore:Victor Graphics, Inc.

DeWaters, 1.E. and DiGiano, F./\, (1990). 'The Influence ofOzonized Natural Organic Matter on the Biodegradationof a Micropollutant in a GAC Bed'. 1. Am. Water Works

JKTI, Vol. 8, No. 1-2, Desember 1998

Assoc .. August: 69- 75.Harrington, G.W. and DjGiano, F./\. (1989) .Adsorption

Equilibria of Natural Organic Matter After Ozonization'.1. Am. Water Works Assoc., June: 93-101.

Kruithof, 1.c., van der Gaag, M./\., and van der Kooy, D.(1989). 'Effect of Ozonization on Humic Substances inWater' in Suffet, I.H. and MacCarthy, P (eds), AquaticHumic Substances: Influence on Fate and Treatment ofPollutants. Washington, DC: American Chemical Society.

Le Tareau, P and Rovel, 1.M. (1982) 'Some Examples ofOzone Use in Industrial Wastewater Treatment' inMasschelein, W. (ed). Ozonisation Manual for Water andWastewater Treatment. Chichester: John Wiley & Sons

Mulyanto, A. (1995). 'Colour Removal of Fresh Waters byOzonization and Coagulation'. J. PII .., 03(02): 50-55.

Nicoll, E.H. (1988). Small Water Pollution Control WaterWorks: Design and Practice. Chichester: Ellis HorwoodLimited.

Rice. R.G. and Browning, M.E. (1980) Ozone for IndustrialWater and Wastewater Treatment: A Literature Survey.EPA-600/2-80-060.

Poppinghaus. K. Fresenius, w., und Schneider, W. (1994)Abwassertechnologie: Entstehung, Ableitung.Behandlung, Analytik der Abwaesser. Springer-Verlag,Berlin.Van Leeuwen, J. (1987) 'Preliminary Investigation intothe Improvement of the Biodegradability of OrganicSubstances in Surface Waters and Effluents throughOzonization' Wat. set. Tech., 19: 931-937.

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