Welcome to Bekkelaget Wastewater Treatment Plant
FACTS:
• 35-40% of all wastewater from Oslo, treated at Bekkelaget WWTP
• Plant put in operation in 2000
• Owned by the City of Oslo, operated by the private company Bekkelaget Water inc. (BEVAS)
• Approximate 280.000 pe
• Average daily flow ~100.000 m3/d
• Outlet demands:P-removal > 90%N-removal > 70%(including overflow)
• Sludge production ~5.500 tons DS/year
• Gas production: 3.700.000 Nm3
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Concession
• New demands from 01.01.2009:
– Nitrogen 70% of all nitrogen must be removed
– Phosphorus: 90% of all phosphorus must be removed
– Organic matters: 70% of organic matters as BOD5,must be removed
– And the total amount of overflow must be less than 2% of the total loads of nitrogen, phosphorus and organic matters
These new demands together we increasing load to the plant will cause some challenges in the future
Water capacities
• Dry weather flow 1450 l/s -125.000 m3/d biologically treated (max capacity 1900 l/s)
• Water flow rates between 1900-4000 l/s is treated chemically
• Water flow rates between 4000 - 6000 l/s is treated through 3 mm screens
Water and sludge treatment process
Primary sludge Buffertank
Buffer S
ilo
S
ilo
Bio sludge
Dewatering
Thickener
Digester Digester
Biogas
OverflowMagasin~35.000m3
4000 l/s < Q < 6000 l/s
Sand, grit and screenings FeSO4
PAX-18
Activated sludge
ClarifierPrimary Filter
PrecipitationPrimary
1900 l/s<Q< 4000 l/s
Q=1900 l/s
PAX-18
Q<1900 l/s
Biogas- upgrading
Overview
Water treatment
1. Inlet tunnel
2. Screens, sand and grit removal
3. Primary settling/ direct precipitation
4. Bio step, activated sludge
5. Clarifiers
6. Extra space(not in use)
7. Sand filters
Sludge treatment
8. Digesters
9. Sludge treatment
10.Sludge treatment
11.Ventilated air treatment – odor control
12.Biogas, upgrading (out)
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212 m
Sludge – heating system - existing
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Primary sludge
Sludge buffertank
RSL 2
S
ilo
S
ilo
Biosludge
De watering
Thickener
Digesters
Biogas
Sludge buffertank
RSL 1
Boiler (gas/oil)
Thickener
Heating – buildings and planVentilation + adm in building
Sludge – heatingsystem
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Primary sludge
Sludge buffertank
RSL 2
S
ilo
S
ilo
Biosludge
De watering
ThickenerBiogas to upgrading
Sludge buffertank
RSL 1
Excess heat from upgrading plant
Boiler (Gas/oil)
Thickener
Upgrading biogas
Heating – buildings and planVentilation + adm in building
Pellets
Cooling of sludge
Heat pump
Without heatpump in operation
Digesters
Use of biogas
• The plant produces large amounts of biogas
• It is similar to f.ex Propan and has a high heating value
• Until 2006 – gas used for sludge drying and heating of sludge and buildings
• From 2006-2010, only 50% of produced energy from gas used
• Different solutions discussed– Electricity production – Fuel production, two different options – gas production similar to
2,2 million liters of diesel pr year– Heat to district heating system
Bærekraftig driftOptimalisering energibruk - BRA
BRA nå og fremtiden:Til nå– Anlegget satt i drift 2000, relativt moderne anlegg– Lys og ventilasjonsstyring– Frekvensomformere– Stort overskudd biogass
Fremover– Varmepumper– Oppgradere/frigjøre biogass til drivstoff– Pellets som støttevarme– Fokus på O2 regulering, godt nok– Bruk av lavverdig energi
• I forbindelse med vurdering av alternativ fremtidig bruk av biogassenpå BRA ble det utarbeidet et miljøregnskap -
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Upgraded biogas (biomethane)
• Upgraded biogas (biomethane) as fuel is almost CO2 neutral and is the most environmental friendly of fuels commercially available
• In 2009 the biogas production was 3.600.000 m3 (60% methane), equivalent of 24 million kWh/year or 2.2 mil liter diesel. The production can keep 80 busses running on biomethane, every day
• The plant for upgrading of biogas to biomethane was put in operation early in 2010
• The investment costs for this plant was 32 mill NOK. Including necessary investments rebuilding the heating system and the sludge treatment process the total cost was 55 mil NOK
gassholder
Activated coal - filter
Gas drier
CO2 absorption
CO2 removal/ COOAB recovery
Odorizer
High pressure compressor
CO20,5 bar
2 bar
200 bar
COOAB ® process – CO2 absorption
Water quality 2010
*Concession numbers are incl. overflow.
**Results from 2010 incl. overflow
Total flow: 440,6 mill m3 Treated volume: 39,98 mill m3
Overflow: 0,67 mil. m3
in (tons)
out (tons)
Removed (%)**
Concentration (mg/l)
Concession (tons)*
Phosphorus 161,4 12,48 92,3 0,31 90%
Nitrogen 1 328 408 69,3 10,0 70%
BOD 7 313 129 97,5 3,1 70%
COD 16 965 - - - -
Sludge
Limit
(mg/kg TS)2002 2009
Pb (mg/kg TS) 80 36,8 18,8
Cd (mg/kg TS) 2 1,48 0,68
Hg (mg/kg TS) 3 1,04 0,65
Cr (mg/kg TS) 100 34,3 19,8
Ni (mg/kg TS) 50 26,3 17,1
Cu (mg/kg TS) 650 703 277
Zn (mg/kg TS) 800 398 410
• Sludge production: 17.700 tons sludge, or 5.400 ton TS / year• 90% of sludge are being used as a fertilizer for grain production
Bekkelaget Water inc.(BEVAS)
• The Municipality of Oslo has signed an operation contract for Bekkelaget WWTP (BRA) with BEVAS for 15 years
• Operation contract stared in October 2001
• BEVAS is owned by Läckeby Water Group (Sweden)
• Läckeby also have interests in Purac AB, and offer services within, construction, design, building, equipment and operation.
• The company has 180 employees, has a turnover on 600 mil. SEK, and runs businesses in 10 countries