innovative biological proceses hallvard...

NTNU - Norwegian University of Science and TechnologyDep. Hydraulic and Environmental Engineering

Prof. Hallvard Ødegaard

INNOVATIVE BIOLOGICAL PROCESES

Hallvard Ødegaard

NTNU/XUAT Postgraduate course 21.05.02-31.05.02: Wastewater as a resource



1. In plants with suspendedbiomass, the activatedsludge process, themicroorganisma areflocculated in suspendedflocs. Recirculation ofsludge is needed

2. In plants with attachedbiomass (biofilm) the microsare growing on a fixed surfaceNo recirculation is needed

THE PRINCIPLES OF BIOLOGICAL TREATMENT

OF WASTEWATER



IMPORTANT DIFFERENCES BETWEEN ACTIVATED SLUDGE PROCESSES AND

BIOFILM PROCESSES

• Higher active biomass per unit volume in biofilm reactors

• More specialised biomass per unit volume in biofilm reactors

• Sludge concentratioN in biofilm reactor oulet far lower in biofilmreactors

• Biofilm reactors are independent of sludge separation reactordownstream



COMPACT, COVERED, HIGH-TECH TREATMENT PLANTS WILL BE ASKEDFOR IN THE FUTURE

There might be a change from activated sludge processestowards biofilm processes



THE REASON FOR THE GROWING INTEREST IN BIOFILM REACTORS

1. Less space required

2. Final result less dependent upon biomass separation

3. More specialised biomass at a given point in reactor train

Bio Sep Bio Sep

3.000-5.000 mg/l 100-150 mg/l

Activated sludge system Biofilm system

C,N,DN C,N,DN C,N,DN C N DN



BIOFILM PROCESSES ARE GOVERNED BY DIFFUSION



DIFFERENT TYPES OF BIOFILM REACTORS

Rislefilter Biorotor Moving bed

Stasjonærtdykket filter

Granulærtdykket filter

Fluidized bed



TRADITIONAL BIOFILM PLANTS

TRICKLING FILTER

ROTATING BIOLOGICAL CONTACTOR (RBC)



SUBMERGED BIOFILTER PLANT



THE MOVING BED BIOFILM PROCESS(The Kaldnes-process)



THE PRINCIPLE OF THE MOVING BED REACTOR

Aerobic reactor Anaerobic/anoxic reactor



CHARACTERISTICS OF THE BIOFILM CARRIERS

Biofilm carrier :Material : Polyethylene (density 0,95 g/cm3)Size : K1 - Diam./Length = 10mm/7mm

K2 - Diam./Length = 15mm/15mm

K1

K2Surface area K1 K2

Per carrier (mm2) Total Effective for biofilm growth

670490

23001530

Specific area (m2/m3) Total at 70 % carrier filling Effective for biofilm growth

490350

330220



THE K2 CARRIER WITH BIOFILM



��

��

��

��

��

��

��

��

��

��

� ��

��

��

TYPICAL MOVING BEDPROCESSES FOR

DIFFERENT APPLICATIONS



BOD/COD removal

BOD/COD removal only

BOD/COD-removal combined with P-removal

High-rate pre-treatment for upgrading of activated sludge plants

��

��



Substrate loading rate [kg/m3*d]

Sub

stra

te re

mov

al ra

te

[kg/

m3 *d

]

1 2 3

a. Specific area: 1<2<3

Substrate loading rate [kg/m2*d]

Sub

stra

te re

mov

al ra

te

[kg/

m2 *d

]

1 2 3

b. Specific area: 1<2<3

COMPARISON BETWEEN THREE CARRIERS WITH DIFFERENT SPECIFIC SURFACE AREA [r = rmax

. L/(K+L)]

At low loading rates, the difference in volumetric substrate removal rate seem to be small. This is hypothesized to be caused by the fact that carriers with lower specific area have higher biomass load. Comparisons should, therefore, be made based on effective surface area rates



Line 1KMT

Line 2AWT

Line 3ANOX

Storagetank

S

S

S

S

S

S

Inletchamber

S

Aeratedbioreactors

S = sampling

Sludge

Sludge

Sludge

Settlingtanks

KMT- K1 KMT- K2

AWT ANOX

Carriers usedPilot plant

Specific surface area KMT carrier K1 KMT carrier K2 AWT carrier ANOX carrier

Estimated surface area[mm2/piece]

total : 670effective : 490




Bulk carriers [number/litre] 1030 159 203 24Specific surface area[m2/m3]





Carrier characteristics



REMOVAL RATES VERSUS LOADING RATES FOR FILTERED COD (SCOD) IN PERIOD 1

0,0

0,5

1,0

1,5

2,0

2,5

3,0

3,5

0,0 2,0 4,0 6,0

Filtered COD loading rate [kg SCOD/m3*d]

Filte

red

CO

D re

mov

al ra

te[k

g S

CO

D/m

3 *d]

KMT AWT ANOXy=0.79x-1.00 y=0.72x-0.77 y=0.66x-0.78

0

5

10

15

20

25

30

0 10 20 30 40 50

Filtered COD loading rate [g SCOD/m2*d]

Filte

rd C

OD

rem

oval

rate

[g S

CO

D/m

2 *d]

KMT AWT ANOXy=0.79x-3.30 y=0.72x-4.17 y=0.66x-6.95

When presented in terms of volumetricrates, the performance seems to beclose to equal at low loading rates

When presented in terms of effectivearea rates, the loading at a given flow is shown to be higher for the low ss carriers



0

5

10

15

20

25

30

35

40

45

50

0 20 40 60 80 100


Filte

red

CO

D re

mov

al ra

te [g

SC

OD

/m2 *d

]

KMTAWTANOX

100 % removal

0

5

10

15

20

25

30

35

40

0 50 100 150 200 250 300 350

Bulk filtered COD concentration (g SCOD/m3)Fi

ltere

d C

OD

rem

oval

rate

(g S

CO

D/m

2 *d)

KMT

AWT

ANOX

COMPARISONS OF CARRIERS WITH RESPECT TO EFFECTIVE SURFACE AREA REMOVAL RATE OF SCOD

Versus loading rate - period 2All reactors same carrier area

Versus bulk concentration All data from period 1 and 2

Max rate ~ 30 g SCOD/m2.dAvailability of BSCOD limiting up to

a loading of around 50-60 g SCOD/m2.d

1. order at low concentrationsClose to { 1/2 order up to about 200 mg/l

0 order at high concentrations



0

5

10

15

20

25

30

35

40

0 20 40 60 80


Filte

red

CO

D re

mov

al ra

te

[g S

CO

D/m

2 *d]

KMTAWTANOX

0

2

4

6

8

10

12

14

0 10 20 30 40 50


Filte

red

CO

D re

mov

al ra

te

[g S

CO

D/m

2 *d]

K1-375 minK2-375 minK1-52 minK2-52 minK1-27 minK2-27 min

SCOD REMOVAL RATES VERSUS LOADING RATESFirst part of experiments

Same residence time in all reactors

The fact that all carriers are following thesame line, is evidence of the fact that eff. surface

area is the key design parameter.Shape and size of carrier are of minor importance at same eff. surface area

Second part of experimentsVariations in residence time

Again small differences between carriers. Small differences between

various residence times. Note, higher slope of curve at long RT (375 min)Reason : More extensive hydrolysis



0

20

40

60

80

100

120

140

0 50 100 150 200

Tot COD loading rate (g COD/m2*d)

Obt

aina

ble

rem

oval

rate

(g

CO

D/m

2 *d

KMT

AWT

ANOX

100 % removal

0

10

20

30

40

50

60

70

0 20 40 60 80 100 120

Tot COD loading rate (g COD/m2d)

Obt

aina

ble

rem

oval

rate

(g

CO

D/m

2 d)

K1-400 min

K2-400 min

K1-50 min

K2-50 min

K1-30 min

K2-30 min

100 % removal

“OBTAINABLE” REMOVAL RATE VS TOT COD LOAD RATEFirst part of experiments Second part of experiments

”Obtainable" COD removal rate : (CODinfluent-SCODeffluent)*Q/ADemonstrates removal rate of tot. COD if all particles > 1 µm were removed

Very high loading rates can be used (> 100 g COD/m2.d) without loosing much on removal rate if biomass can efficiently be removed.



DISCUSSION AND CONCLUSIONS

1. It is clear that the MBBR should be designed according to effective surface area loading rate and that comparisons between carriers must be based on this

2. At low loading rates, an effect of hydrolysis of slowly biodegradable organic matter can be expected resulting in an influence of residence time

3. At high loading rates and low residence times (< 60 min) little hydrolysis willoccur. Particles will pass through the reactor more or less “untouched” while the easily biodegradable, soluble organic matter is degraded very rapidly.

4. To take the full advantage of the MBBR for COD removal, one may, therefore, use high loading rates (> 30 g SCOD/m2.d or 100 g COD/m2.d) , resulting in very compact reactors, provided that an enhanced biomass separation method is useddownstream, i.e. coagulation by cationic polymer or metal salts (if P removal).

Chem.

Pretreatm.



TotalCOD

SuspendedCOD

ColloidalCOD

SolubleCOD

350

225

50

75

60

70

9510

75

40

6020

15010

40

70

90

190

70

Inert

Biomass

FatCarbohydrates

Proteins

Humics

VFA

F, C, P.

NBD

NBD

SBD

NBDSBD

EBD

SBD

EBD

NBD NBD

SBD

EBD BM

NBD

SBD70

50

50

15

1035

150

70

80

10

100

25

351050

95}275

35

79% of 350

suspended

10% of 350

soluble

NBD-non biodegrabable, SBD-slowly biodegradable, EBD-easy biodegradable

A CONCEPTUAL MODEL OF COD-CONVERSIONIN A MOVING BED BIOFILM REACTOR



Air Water Biofilm Support material

Deg

rada

tion

prod

ucts

oxid

ation

Deg

rada

tion

Organic particle

Zone of oxygen shortage

Dissolvedorganics

Possible effect of an adsorbed organic particle on the biofilm surface.

POSSIBLE EFFECT OF AN ADSORBED ORGANIC PARTICLE ON THE BIOFILM SURFACE



MOVING BED PROCESSES IN COMBINATIONWITH COAGULATION

The facts that: • the biofilm is primarily active in biodegradation of readily biodegradable

soluble organic matter • the particles pass through the reactor more or less unchanged

make it natural to combine the MBBR (for the removal of soluble matter) with coagulation (for the removal of particles) according to two main principles :

1. Post-coagulation - Particles are allowed to enter the MBBR, pass through it, and removed downstream by coagulation together with biomassEspecially suitable in high-rate plants for COD- and SS-removal only

2. Pre-coagulation - Particles are removed ahead of the MBBR, thus reducing the organic load on this Especially suitable in low-rate plants for nutrient removal



HIGH-RATE MBBR IN POST-COAGULATION MODE

05

101520253035404550

0 20 40 60 80 100Filtered COD loading rate [g SCOD/m2*d]

Filte

red

CO

D re

mov

al ra

te

[g S

CO

D/m

2 *d]

K1 K2 100%0

20

40

60

80

100

120

140

0 50 100 150 200Total COD loading rate [g COD/m2*d]

Obt

aina

ble

rem

oval

rate

(C

OD

in-S

CO

Dou

t) [g

/m2 *d

]K1 K2 100%

Chem.

Pre-treatm.



HIGH-RATE MBBR IN POST- COAGULATION MODE

Very high loading rates can be accepted - up to 100 g COD/m2d if all particles/biomass is removed downstream. However, settleability strongly dependent upon organic loading :

0 %

20 %

40 %

60 %

80 %

100 %

0 20 40 60

Bioreactor loading rate, g COD/m2d

SS

-rem

oval

in s

ettli

ng ta

nk (%

) K1,v=0,05 m/h

K1,v=0,35 m/h

K1,v=0,65 m/h

0 %

20 %

40 %

60 %

80 %

100 %

0 10 20 30 40

Bioreactor loading rate, g SCOD/m2dS

S-re

mov

al in

set

tling

tank

(%) K1,v=0,05 m/h

K1,v=0,35 m/h

K1,v=0,65 m/h

CONSEQUENCE : Settling should be enhanced by coagulation



REMOVAL OF SS IN HIGH RATE MBBR EFFLUENT

0 %10 %20 %30 %40 %50 %60 %70 %80 %90 %

100 %

0,0 0,1 0,2 0,3 0,4

Dose of coagulant [mmol Me/l]

Rem

oval

of S

S

PAX XL 60FeCl3

0 %10 %20 %30 %40 %50 %60 %70 %80 %90 %

100 %

0 1 2 3 4 5 6 7

Dose of polymer [mg/l]

Rem

oval

of S

S

Zetag 67, Medium chargeZetag 75, Medium-high charge Zetag 78, High charge

a. Addition of inorganic metal salts b. Addition of cross-linked (25 %), (PAX - prepolymerised AlCl3) high MW cationic polymer



BOD/COD removal in comb. with P-removalTreatment results from two Norwegian plants

Steinsholt treatment plant Eidsfoss treatment plantParameterIn, mg/l Out, mg/l % removal In, mg/l Out, mg/l % removal

BOD – avemax

min

3981720120

10385

97,499,793,5

771 (LOC)18232

6,31 (LOC)9,84,2

91,81 (LOC)94,483,6

COD – avemaxmin

8332760190

4613030

94,498,483,2

- - -

Tot P – avemaxmin

7,112,04,0

0,300,720,12

95,898,892.6

9,827,54,4

0,170,940,03

98,299,888,3

SS - avemaxmin

- 21308

- - 11275

-

1 These values are based on soluble organic carbon (LOC)



High-rate pretreatment for upgrading ofactivated sludge plants

Results from solids contact process testing in New Zealand��

��

��

��

��

��

��

!""

#$"

#""

%$"

%""

$"

"

��&��

$� ��

��

��

��

��

��

��

��

!""

#$"

#""

%$"

%""

$"

"

��&��

$� �� '��(

#)�$��#'%)�*��$�

#'+�,�(�%$�-.�

�� '��($#�*��#'#/�)��$�

#'+�,�(�%/�%.�

+�� $

0�� '��$

� ��'��$

+�� $

0�� '��$

� ��'��$



NITRIFICATION

Nitrification after pre-coagulation

Nitrification aftercarbonaceous removal

Post-nitrification afteractivated sludge plant

��



NITRIFICATION

2.5

2.0

1.5

1.0

0.5

0.00 2 4 6 8 10

a)

Am

mon

ia re

mov

al ra

teg

NH

4-N/m

2 d

Oxygen concentration, mg O2/l

2.5

2.0

1.5

1.0

0.5

0.00

b)

Ammonium concentration, mg NH4-N/lN

itrifi

catio

n ra

te,

g N

H4-N

/m2 d

DO=9mg/l

DO=6mg/l

DO=3mg/l

0.4g BOD7/m2d

Organic load=0.0g BOD7/m

2 d

1.0

2.0

3.0

4.0

5.0

6.0

7.0

1 2 3 4

Three factors determine the nitrification rate :1. The load of organic matter2. The ammonium concentration (< 3 mg NH4-N/l)3. The oxygen concentration



NITROGEN REMOVAL

Pre-denitrification

Post-denitrification

Post-denitrification afternitrifying activated sludge plant

Combined pre- and post-denitrification

��

��

��



CONCLUSIONS

1. The development of the Kaldnes moving bed biofilm process is anexcellent example of fruitful co-operation between university and industry. The reactor have been developed from idea to being wellestablished in the market-place within a time span of 10 years

2. The reactor has proven useful in all applications of wastewatertreatment where a biological process is needed.

3. It gives a very compact bioreactor and offers great flexibility inuse that makes the process very useful when upgrading activatedsludge plants .

innovative biological proceses hallvard...

Documents