Moving Bed Biofilm Reactors (MBBRs) treating wastewaters

Moving Bed Biofilm Reactors (MBBRs) treating wastewaters from the forest

industry –Experience from more than two

decades with pure MBBR and BAS™processes

June 2021

Daniel Lamarre and Thomas Welander

Veolia Water Technologies Canada /AnoxKaldnes

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Presenters

2

Thomas WelanderChief Visionary Officer

Daniel LamarreBiological Process Specialist

Veolia Water Technologies, Sweden

ANOXKALDNES

VWT Canada

1. P&P effluents

2. Effluent treatment options

3. MBBR process

4. BAS and nlBAS

5. Conclusion

3

Agenda

The Pulp and Paper Industry worldwide

PACWEST 2021 4

Rank CountryProduction (million metric tons)

1 China 108,5

2 United States 71,8

3 Japan 26,1

4 Germany 22,6

5 South Korea 11,5

6 Brazil 10,3

7 Canada 10,2

8 Finland 10,2

9 Sweden 10,1

10 Indonesia 9,8

Top Ten producers of Pulp and Paper (2016)

Wastewater Characteristics

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P&P Wastewaters characteristics - general

PACWEST 2021 6

Often High flows - up to 150 000 m3/day (pulp mills, lower for paper mills)

COD-loads 1000- 250 000 kg COD/day

COD-concentrations ranging from 500 – 10 000 mg/L

Biodegradability of COD ranging from 50-95 %

High temperature, usually around 35°-60°C

Lack of nutrients, N and P

o Use of Biofilm Carriers (Media) to create large biofilm surface area – active biomass in bioreactor

o All the biomass is fixed on the media

o No suspended growth (mixed liquor)

MBBR = Moving Bed Biofilm Reactor

MBBR TechnologyMBBR Technology

PACWEST 2021

Aeration system and Media retention sieves

8

• Aeration provides oxygen for biomass and mixing of the media• Coarse bubble perforated pipe aeration grids

• Media retention sieves• 15mm perforated plate

• 50 mm head loss per reactor

• 304 or 316 SS

• No moving parts

• No maintenance

PACWEST 2021

Simple and Robust Process

9

• Compact, low HRT

• Very simple operation• Continuous flow

• No recycle loop

• Robust• Toxic shocks

• Variable loads

• No maintenance!

PACWEST 2021

Treatment options for P&P

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ASB• Aerated Stabilization Bassins• Very large lagoons – footprint intensive• Sub-optimal Effluent quality

• Good but not very good...

• Simple operation• Periodic dredging required• About 1/3 of canadian P&P WWTP

Traditional Process options

PACWEST 2021 11

AST• Activated Sludge Treatment• Much more compact than ASB• Large concrete tanks• High cost of civil works• Good effluent quality• More operator-intensive than ASB

EQ + Primary

AerationTank

MBBR• Flow-trough fixed-film process

• Most compact – lowest civil costs

• Allows high-rate secondary clarification

• Most efficient for small flows or diluted wastewater

• Approximately 40 full-scale MBBR plants in P&P

Compact and efficient Process options

MBBR-based

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BAS-process• MBBR + AST (activated sludge)

• More compact than AST

• Less compact than pure MBBR

• Lower OPEX than AST and MBBR

• More robust than AST

• Approximately 60 full-scale plants in P&P

PACWEST 2021

DAF

SLUDGE

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1- Pure MBBR

PACWEST 2021

• Mainly used for:• Paper mills• Small pulp mills• Large pulp mills with very diluted effluent

• Biomass separation in high-rate secondary separator• High-rate DAF• Lamella clarifier

• Polymer may be required for solids clarification.• Operating the MBBR at lower COD loads (3-4 kg COD/m3 reactor/d) helps lower

polymer requirements (down to 0 mg/L)

”Pure” MBBR process

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SLUDGE

DAFMBBR#1 MBBR#2

PACWEST 2021

• Pilot test results from MBBR + DAF (Kraft mill)

• High-rate DAF provides low effluent TSS

• Upstream MBBR operation is linked with DAF efficiency

• DAF float (sludge) at 2,5 to 5% solids

MBBR: DAF clarification

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Start PO4 addition in MBBR Start PO4 addition in MBBR

RAW WATER

MBBRDAF

PACWEST 2021

MBBR - Full scale references

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Name Country Start-up

production COD-loadKg/d

MBBR-volume, m3

Carrier Comment

Wargön Sweden 1994 Sulphite 49 000 1000+1000 Natrix , A,B No primaryclarification

Bäckhammar Sweden 1996 Kraft (paper) 7000 1500 Natrix C No primaryclarification

Pulp Mill Canada 2000 Kraft 20 000 1700 Chip P Thermophilic

Korsnäs Frövi Sweden 2013 Kraft(packaging)

11 000 2000+2000 K5 EDTA-removal

Natrix, 200 m2/m3

No longer used by VeoliaBioChip P900 m2/m3

K5: 800 m2/m3

Preferred media by VeoliaPACWEST 2021

Pure MBBR – sCOD and EDTA removal

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Korsnäs FröviDischarge limits for EDTATreatment of sour bleaching filtrateCOD 4000 mg/L (11 000 kg/d) EDTA 200 mg/L (550 kg/d)Design based on lab and pilot trials

Thermophilic COD-removal Mesophilic EDTA-removal

MBBR 12000 m3

55°18h HRT

MBBR 22000 m3

37°C18h HRT

Cooling

EDTA-degrading bacteria are slowgrowing❑ Biofilm at low load❑ AS with long sludge age (low load)

Effluentdischarged toaerated pond

PACWEST 2021

Pure MBBR - Full scale design example

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Typical Kraft mill effluentMBBR for removal of soluble biodegradable COD

Typical Design Loadings on soluble biodegradable COD• 4 to 8 kg sbCOD / m3 reactor volume /d

EQtank

MBBR35°C

4-24h HRT(according to sCOD

concentration)

Cooling High rate DAF25-30 m/h AVG

MBBR

PACWEST 2021

19

2- The BAS process

Activated sludge

MBBR

o High-rate MBBR upstream of an Activated Sludge process

o BAS = Biofilm Activated Sludge

o More compact than AST only

o Lower operating costs

▪ Lower sludge production

▪ Lower nutrient dosage

o Better sludge settling properties than AST

The BAS process

20PACWEST 2021

3-4 kg Soluble COD/m3 reactor/day

The BAS process

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10-20 kg Soluble COD/m3 reactor / day

35-60 % removal of SCOD

Conventional activated sludge:1.5 kg SCOD/m3 reactor and day

Typically 50% the size of an AST

PACWEST 2021

❑Upgrading of existing activated sludge❑Greenfield

The BAS process - principle

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MBBR

▪ Removes majority of easily biodegradable sCOD

▪ Generates free biomass, which is food for the predators in the AS

▪ Protects AS from disturbances (acts as buffer tanks / toxic shock dampener)

Activated Sludge

▪ Removes remaining biodegradable COD at low load

▪ Degrades biomass from upstream MBBR resulting in activated sludge with good settling properties (low SVI)

PACWEST 2021

SVI

0,00

100,00

200,00

300,00

400,00

Existing activated sludge process converted to BAS

process by installing MBBR upstream

The BAS process – low SVI

PACWEST 2021

The MBBR removes the easily degradable COD which makes it more difficult for filamentous bacteria to grow in the activated sludge reactor.

Improved sludge characteristics

Before MBBR installation After MBBR installation

Massive growth of filamentousbacteria causes sludge bulking

Big and compact flocs withexcellent settling properties

Effluent TSS of 10-30 mg/L without any chemical additions

o Most P&P wastewaters are nutrient deficient (lack of nitrogen and phosphorus in

relation to COD)

o Possible to operate the BAS as Nutrient Limited

o Nutrients added only to the MBBR, controlled for limiting COD-removal to 40-60 %

o Slimy (zoogloeal) biomass is then formed in the MBBR

o The slimy biomass is easily consumed in the following activated sludge reactor

o The formation and successive consumption of biomass decreases the overall sludge

production

o It also lowers the N and P dosage requirements

25

Lower sludge production: Nutrient Limited BAS™ (NLBAS™)

MBBR biomass in NLBAS

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- Mainly free bacteria

- Few predators

Activated Sludge biomass in NLBAS

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Mainly predators, eating free bacteria

Lower sludge production with the Nutrient Limited BAS™ (NLBAS™)

Sludge Yield

0.000

0.200

0.400

0.600

0.800

1.000

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Low sludge production with the NLBASTM has been demonstrated

• 0.07-0.15 kg TSS/kg CODreduced

(Data from long term operation of five full scale plants)

• This is 30-50 % lower than for an Activated Sludge (AST)

BEFORE NLBAS WITH NLBAS

Sludge production rate

BAS™ NLBAS™ “pure” MBBR

Total sludge production for the process(kgVSS/kgSCODremoved)

0.15 – 0.2 0.1 – 0.15 0.2-0.3

Sludge production across MBBR stage(kgVSS/kgSCODremoved)

0.25 – 0.35 0.25 – 0.35

Comparison of sludge production

Full scale nlBAS™ comparison

Six (6) Full-scale plant results and parameters of interest

PACWEST 2021 30

Parameter BAS process AVERAGE

Värö(Sweden)

Hylte(Sweden)

Kraft Mill(Germany)

Pulp mill(Canada)

Kvarnsveden(Sweden)

Santa Fe(Chile)

Mill processKraftTCF/ECF

TMP andrecycledpulp

Kraft(ECF/TCF)

BCTMP TMP (paper)BleachedEucalyptusKraft

Flowrate (m3/d) 20000 20000 50000 20000 35000 120000

COD mass flowrate*(ton/d)

35/50(sCOD)

50/82(tCOD)

53/80(tCOD)

n.a./140(sCOD)

90/144(tCOD)

115/127(tCOD)

MBBR HRT (h) 4.3 6 3 7.2 3.2 1.8 4.2AS HRT (h) 12 18 13 64 24 4.8 22.6

MBBR load* (kgCOD/m3.d)

9.7/14 10/16.4 8.7/13 n.a./23 19/31 13/14 12/19

Overall BAS load* (kgCOD/m3.d)

2.6/3.7 2.5/4.1 1.6/2.4 n.a./2.4 2.3/3.6 3.5/3.8 2.5/3.3

Overall BAS sCODremoval (%)

75 89 70 80-85 90 70-80 80

MBBR sCOD removal (%)

30-40 50 35-40 30-50 45 n/a 42

Effluent TSS (mg/L) 20 5 (No chemicals) <20 n/a 11 20 15

Sludge yield (gTSS/gCODremoved)

0.07 0.14 0.12 0.12-0.17 0.14 0.12 0.14

SVI (mL/g) n/a 60 100-140 50-100 70 50 75

Conclusion

PACWEST 2021 31

o MBBR is well adapted for treatment of P&P effluent

o Numerous references (30 years)

o Preferred Processes for P&P are NLBAS™ and MBBR + DAF

o MBBR + DAF is the most compact option for diluted wastewater

o NLBAS™ (mostly for pulp mills) provides:

o Low sludge production

o Low nutrient dosage

o Good sludge settleability

o No polymer

Questions?

32

COD load

MBBRnlBAS

PACWEST 2021