mbbr

1

INNOVATIONS IN WASTEWATER TREATMENT -

THE MOVING BED BIOFILM PROCESS

Xi’an May 2005

Hallvard Ødegaard

Norwegian University of Science and Technology (NTNU)Department of Hydraulic and Environmental Engineering

NO-7491 Trondheim, NORWAY

[email protected]

2

Where is Norwayand were is Trondheim ?

Far north

3

• The country is situatedfar north (55-70 oN), but the Golf streamgives a pleasant climate

• The country has as anabundance of waterresources – both freshand saline water

• The country has anextremely long coastlinewith long fjords andthousands of islands

• The country is sparselyinhabited (4 mill) exceptfor the south-easternregion around Oslo

Norwayand

water

4

My wastewater treatment philosophy

Enhancedprimary

Removal of solubles

Organic concentrate

Carbon source

Biogas

Take out the particles first

Make use of the concentrate

Then deal with the solubles

Nutrients

Heat

Carbon

Nitrogen

Phosphorus

5

Expected trend:From area consuming open activated sludge plants to compact, covered biofilm reactor plants

6

THE REASONS FOR THE GROWING INTEREST IN BIOFILM REACTORS

1. Less space required

2 Final result less dependent upon biomass separation

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

Activated sludge system Biofilm system

Bio Sep Bio Sep

3.000-8.000 mg/l 100-200 mg/l

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

7

THE PRINCIPLE OF THE MOVING BED BIOFILM REACTOR (MBBR)

Aerobic reactor Anoxic reactor

8

THE MOVING BED BIOFILM PROCESS(The Kaldnes-process)

9

Design

(m2/m3)

(1200)-

(m2/m3)

500335

(m2/m3)

350235

(m2/m3)

500335

Specific biofilm area– Effective in bulk– Effective at 67 %

filling fraction

48/2,225/1215/159/7Diam/Length (mm)

BiochipK3K2K1Carrier

K1

K2

CHARACTERISTICS OF THE ANOX KALDNES BIOFILM CARRIERS

Material : Polyethylene PEHD (density 0,95 g/cm3)

10

MBBR’s UNDER CONSTRUCTION

Aerobic reactor with aeration system Anoxic reactor with horizontally and vertically mounted cylindrical mounted shaft mixers and bar sieves rectangular mesh sieves

11

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TYPICAL MOVING BEDPROCESSES FOR

DIFFERENT APPLICATIONS

12

PROCESSES FOR BOD/COD REMOVAL

Coag.

High rate MBBR followed by coagulation/flocculation/separationbiomass

(Coag.)

MBBR followed by biomass separationCoagulant only if P-removal isrequired

MBBR pre-treatment to activated sludgeFor upgrading of AS plants

13

THE INFLUENCE OF COD LOADING RATE ON COD REMOVAL RATE

)

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%

a b

Soluble COD removal rate versus soluble

COD loading rate

Soluble COD removal rate versus “obtainable”COD removal rate

14

CLARIFICATION CHALLENGES

At high loading rates, clarification may represent a challenge

0 %

20 %

40 %

60 %

80 %

100 %

0 10 20 30Bioreactor loading [g COD/m2*d]

SS

-rem

oval

in s

ettli

ng ta

nk

v=0.05 m/hv=0.16 m/hv=0.16 m/h w/polymerv=0.35 m/h

0 %

20 %

40 %

60 %

80 %

100 %


SS

-rem

oval

in s

ettli

ng ta

nk

v=0.05 m/hv=0.35 m/hv=0.65 m/h

0 %

20 %

40 %

60 %

80 %

100 %


SS

-rem

oval

in s

ettli

ng ta

nk

v=0.05 m/hv=0.16 m/hv=0.16 m/h w/polymerv=0.35 m/h

0 %

20 %

40 %

60 %

80 %

100 %


SS

-rem

oval

in s

ettli

ng ta

nk

v=0.05 m/hv=0.35 m/hv=0.65 m/h

Clarification problem may, however, be solved by coagulation

15

• Let particulate organic matter be removed by coagulation• Let soluble organic matter be removed by biodegradation (MBBR)• Minimize sludge production – use polymer coagulation• Minimize cost by use of compact unit processes (i.e. flotation)

THE BASIS FOR A HIGH RATE SECONDARY TREATMENT PROCESS

Total COD in wastewater - 100%

1 µm

SCOD PCOD

“True solution” “Particulate fraction” (colloids & SS)

Degradable in MBBR

Coagulation Flocculation

ChemicalsMBBRWe want:

ChemicalsMBBR

We don’t want:

0.1 µm

16

Fine sive MBBR Coagul/Floccul. Flotation

* HRT: 5-10 min * 5 mg polym/g SS+ 35 mg Fe/g SS

(~1 mg pol./l+7 mg Fe/l at 200 mg SS/l)

* HRT: 20-25 min* vf = 5-15 m/h

Sludge production in separation step:1.0 g DS/g SSremoved

* HRT:10 min* 0.8 mm

* HRT: 15 – 45 min* 20-25 g CODfiltered/m2d

(15-20 g BOD5 filtered/m2d)* 65-85 g CODtot/m2d

(45-60 g BOD5 tot/m2d)* Sludge production:

0.5 g DS/g CODf, removed

THE HIGH RATE MBBR PROCESS

CoagulantFe+polymer

Air

CoagulantFe+polymer

Air

Secondary treatment standard + 90 % P-removal) could be reached at thefollowing process conditions (total residence time ~ 1 hr):

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Aeration Aeration Aeration Aeration

Air scouring

Permeate

Concentrate

MBBR 1 MBBR 2Finesieve

MOVING BED BIOFILM MEMBRANE REACTOR (MBB-MR)

18

Transformation of COD in MBBRInfluence of MBBR loading (HRT)

0

10

20

30

40

50

60

70

80

>1 µm 0.1-1 µm <0.1 µm

Size fraction (µm)

Am

ount

of C

OD

(%)

Raw water HRT = 0.75 h HRT = 1 h HRT = 3 h HRT = 4 h

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Performance - example

Parameter Average inletconcentration

(mg/l)

Averageremoval

(%)

CODFCODBODFBODSSNH4-NTot P

39221332217219910,84,6

92-

99-

1009569

0

100

200

300

400

500

600

700

0 5 10 15 20 25 30 35 40

Time (days)

Con

cent

ratio

n (m

g/l)

Raw water COD Raw water FCOD MBBR FCOD Permeate COD

a)

0

1

2

3

4

5

6

0 10 20 30 40

Time (days)

Mem

bran

e ta

nk S

S (g

/l)

0

100

200

300

400

500

600

MB

BR

SS

(mg/

l)

Membrane tank Raw water MBBR

b)

MBBR• Four compartments HRT ~3 hrs• 50% filling fraction (Kaldnes K1)

Membrane reactor:• Zenon Zeeweed 500• Flux: 25 LMH• Recovery: 95%

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Trans membrane pressure after backwash for different hydraulic retention times in the bioreactors feeding the membrane reactor with biological treated water.

-0.6

-0.5

-0.4

-0.3

-0.2

-0.1

00 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18

operation time (days)

trans

mem

bran

e pr

essu

re

HRT = 0h

HRT = 1h HRT = 3h

HRT = 4h

Challenge : Membrane fouling

• Membrane fouling increases with increasing loading (decreasing HRT)

• On-going research will reveal the role of particles and PSD in this?

Trans membrane pressure development versus membrane operationtime as a function of the MBBR loading (HRT) - Small pilot

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Biofilm reactor with plug flow

Rate limited by

NITRIFICATION

Nitrification rate limited in plug flowbiofilm reactorlimited by:

1. Organic matter

2. Oxygen

3. Ammonium

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1. The load of organic matter2. The ammonium concentration (< 3 mg NH4-N/l)3. The oxygen concentration

FACTORS DETERMINING THE NITRIFICATION RATE

2.5

2.0

1.5

1.0

0.5

0.00 2 4 6 8 10

a)

Amm

onia

rem

oval

rate

g N

H4-N

/m2 d

Oxygen concentration, mg O2/l

2.5

2.0

1.5

1.0

0.5

0.00

b)

Ammonium concentration, mg NH4-N/l

Nitr

ifica

tion

rate

, g

NH

4-N

/m2 d

DO=9mg/l

DO=6mg/l

DO=3mg/l

0.4g BOD/m2d

Organic load=0.0g BOD 7

/m2 d

1.0

2.0

3.0

4.0

5.0

6.0

7.0

1 2 3 4

2.5

2.0

1.5

1.0

0.5

0.00 2 4 6 8 10

a)

Amm

onia

rem

oval

rate

g N

H4-N

/m2 d

Oxygen concentration, mg O2/l

2.5

2.0

1.5

1.0

0.5

0.00

b)

Ammonium concentration, mg NH4-N/l

Nitr

ifica

tion

rate

, g

NH

4-N

/m2 d

DO=9mg/l

DO=6mg/l

DO=3mg/l

0.4g BOD/m2d

Organic load=0.0g BOD 7

/m2 d

1.0

2.0

3.0

4.0

5.0

6.0

7.0

1 2 3 4

23

INFLUENCE OF OXYGEN ON NITRIFICATION RATE

(Practical excperiences)

24

NITRIFICATION PERFORMANCE AT Givaudan WWTP SWITZERLAND

10oC

1.17 g NH4-N/m2d

25

Coag.

MBBR pre-denitrificationCoagulation if P-removal required

C Coag.(Coag.)

MBBR post-denitrificationCarbon source addition requiredCoagulation if P-removal requiredMay be operated with CEPT

(Coag.) C Coag.MBBR combination-denitrificationCarbon source requiredCoagulation if P-removal requiredMay be operated with CEPT

C (Coag.)

Activated sludge for nitrificationMBBR post-denitrificationCarbon source requiredCoagulation if P-removal required

Hybrid process – pre-denitrificationin activated sludge. MBBR carriersin last part of reactor to enhancenitrification

N-removal

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The combined pre- and post-denitrification MBBR

Recirculation of NO3-N Carbon

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The Lillehammer plant

Pumpingstation

Gritrem-oval

Pre-settling

Moving bed reactors Flocculationtanks

Post-settlingtanks

CoagulantCarbon

28

The Nordre Follo plant

Flocculationtanks

Pumpingstation

Gritrem-oval

Pre-settling

Moving bed reactors Flotationtanks

Carbon Coagulant

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Flocculationtanks

Pumpingstation

Gritrem-oval

Pre-settling

Moving bed reactors Flotationtanks

Carbon Coagulant

The Gardermoen plant

31

Design values and performances

Parameter Lillehammer Nordre Follo Gardermoen

Design HRT (hrs)Normal flowMax flow

3,22,0

5,03,3

6,34,4

Chemicals consumpt.Coagulantkg PAX/kg Premoved

Carbon sourceg CODadded/g NOx-Nequiv

26,8

4.25 (ethanol)

17,0

5.5 (methanol)

17,5

4.9 (glycol)

Efficiency, 2002Average in-out conc.and treatment efficiency COD (mg/l)Tot N (mg/l)Tot P (mg/l)

In Out %

386 32 9134.6 4.5 854.38 0.10 97

In Out %

452 30 9430 8.0 73

4.86 0.27 94

In Out %

583 32 9451 10 817.01 0.17 98

32

%

20

40

60

80

100

%

20

40

60

80

100 NITROGEN REMOVAL2004

Required: 70 %

Lillehammer average:89,0 %

0 %

20 %

40 %

60 %

80 %

100 %

0 %

20 %

40 %

60 %

80 %

100 %

Nordre Follo average:77,1 %

0 %

20 %

40 %

60 %

80 %

100 %

1. jan.1. feb.1. mar.1. apr.1. mai .1. jun.1. jul.1. aug.1. sep.1. okt.1. nov.1. des.1. jan.

0 %

20 %

40 %

60 %

80 %

100 %

1. jan.1. feb.1. mar.1. apr.1. mai .1. jun.1. jul.1. aug.1. sep.1. okt.1. nov.1. des.1. jan.

Gardermoen average:81,4 %

33

THE LILLEHAMMER WWTP TREATMENT OPERATED AT AND ABOVE DESIGN LOAD

POST-DENITRIFICATION MODE

100

80

60

40

20

01 2 3 4 5

Total empty bed HRT, hours

Tota

l N re

mov

al, %

Design HRT: 3.5 hoursDesign TN-removal: 70%

18/7 1/8 1/9 1/10 17/10

1300

1100

900

700

500

300

100

Date, 1997

100

80

60

40

20

0

TN re

mov

al(%

)

TN-lo

ad(k

g N

/d)

Actual TNremoval

Design avg.TN removal

Actual TNload

Design TNload

100

80

60

40

20

01 2 3 4 5


Tota

l N re

mov

al, %


100

80

60

40

20

01 2 3 4 5


Tota

l N re

mov

al, %


18/7 1/8 1/9 1/10 17/10

1300

1100

900

700

500

300

100

Date, 1997

100

80

60

40

20

0

TN re

mov

al(%

)

TN-lo

ad(k

g N

/d)

Actual TNremoval


Actual TNload

Design TNload

18/7 1/8 1/9 1/10 17/10

1300

1100

900

700

500

300

100

Date, 1997

100

80

60

40

20

0

TN re

mov

al(%

)

TN-lo

ad(k

g N

/d)

18/7 1/8 1/9 1/10 17/10

1300

1100

900

700

500

300

100

Date, 1997

100

80

60

40

20

0

TN re

mov

al(%

)

TN-lo

ad(k

g N

/d)

Actual TNremoval


Actual TNload

Design TNload

Treatment efficiency versus Day to day removal efficiencytotal bioreactor residence time of tot N at actual load compared(based on empty reactor) to design load

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Operating data at Lillehammer WWTP

Temp-erature

oC

Average influent inorg. N conc., mg N/l

Average effluent inorg.

N conc., mg N/l

Removal inorg. N

%

Fraction of denitrification in pre-DN, %

Average Minimum Maximum

6,3 6,0 6,5

17,2 16,1 17,7

3,1 2,2 4,1

92,0 74,5 87,6

16 15 17

Operated at 60 % of design load in combination-DN mode at low temperatures

Bioreactor residence time (hrs)

Influent tot N conc.

mg N/l

Effluent tot N conc.

mg N/l

Removal%

Ethanol consumpt.

kg /kg Nrem.

Temp-erature

oC

Average Minimum Maximun

3.3 1.6 4.5

27 16 48

6.0 2.9

12.7

76 48 91

1.48 (3.1)1

0.55 (1.2)1

2.58 (5.4)1

13.7 11.6 15.7

Operated at design load in post-DN mode (without pre-coagulation)

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OPERATING DATA AT LILLEHAMMER WWTP

Lillehammer, train 1, Nov. 1999

0,0

0,2

0,4

0,6

0,8

1,0

1,2

1,4

1,6

1,8

2,0

0,0 0,5 1,0 1,5 2,0 2,5 3,0

Ammonium load, g NH4-N/m2/d

Rem

oval

rate

, g N

H4-

N/m

2 /d

R4

R4 + R5

Temp. 11 deg C

Very high nitrification rates even at temperatures as low as 11 oC

When calculated on reactor 4 alone, maximum rate was ~1.5 g NH4-N/m2.d

When calculated on both reactor 4 and 5 it was ~1.2 g NH4-N/m2.d up to which nitrification was close to complete.

0

1

2

3

4

0 1 2 3 4 5

Load, g NO3-Neq/m2/d

Rem

oval

rate

, g N

O3-

Neq

/m2/d

Added C/N, g BSCOD/g NO3-Neq

Effl. FCOD, mg/LTemp., deg C

Daytime averagesR7+R8

5.149

11.1

3.458

11.2

3.132

10.2

1. point: DN close to complete because BSCODadded in excess (C/N=6,4)

2. point: Insufficient amount of available BSCOD leading to BSCOD limitation and low DN (60 %)

3. point: C/N-ratio is only slightly higher than 2.but high DN (3.5 g NO3-Nequiv./m2d) becauseno BSCOD limitation prevailed

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DN-RATES VERSUS TEMPERATURE OBTAINED WITH VARIOUS EXTERNAL CARBON SOURCES

3

37

CONCLUSIONS

1. The MBBR has established itself as a well-proven, robust and compact reactor in all applications of wastewater treatment where a biological process is needed (presently > 300 plants in 22 countries).

2. The primary advantage over activated sludge processes is its compactness and no need for sludge recirculation. The advantage of the process over other biofilm processes is its flexibility. The process is favorably used for activated sludge plant upgrade

3. In Europe the MBBR processes are normally combined with chemical P-removal and flotation is favorably used for biomass separation in several cases

4. When using MBBR for N-removal, a combined pre- and post-denitrification is normally recommended because this process combination is superior with respect to process control and performance

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