Welcome to Bekkelaget Wastewater Treatment Plant

Rock cavernsGas holder and Upgrading plant

Admin building

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

Phosphorus and Nitrogen loads to Inner Oslofjord 1910-2004

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