moving bed biofilm reactors (mbbrs) treating wastewaters
TRANSCRIPT
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
>
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
>
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
>
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
12
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
13
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
14
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
15
Start PO4 addition in MBBR Start PO4 addition in MBBR
RAW WATER
MBBRDAF
PACWEST 2021
MBBR - Full scale references
16
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
17
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
18
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
21
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
22
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
26
- Mainly free bacteria
- Few predators
Activated Sludge biomass in NLBAS
27
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
18
-Ja
n-2
00
5
28
-Ja
n-2
00
5
7-F
eb
-20
05
17
-Fe
b-2
00
5
27
-Fe
b-2
00
5
9-M
ar-2
00
5
19
-Ma
r-20
05
29
-Ma
r-20
05
8-A
pr-2
00
5
18
-Ap
r-20
05
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