From Pollution to Solution Bekkelaget Wastewater Treatment Plant Rashid Abdi Elmi [email protected] Holmenkollen ski jump arena Rock caverns Gas holder Admin building 4 Sewage as a resource Treated wastewater Improving water quality and biodiversity in the Oslo fjord – due oxygen rich effluent Upgraded fuel - Fuel for public transportation Biogas Zero CO2 emission/carbon neutral Sludge for agriculture farmland Fertilizer 140 tons phosphorus per year (110 000 bags of mineral fertilizer , 30 kg/bag) Energy extracted from wastewater 250 GWh for District heating: 21 000 apartments, 12,000 kWh/yr pr apartment . Reduction CO2 73 000 ton, corresponds to the emission from 25 000 private vehicles 5 City of Oslo – main sewer system Bekkelaget WWTP VEAS WWTP Prepared enabling change 6 Cavern dimensions 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) 212 m 12 Discharge consent – Compliance limit New discharge consent 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 NB: The population growth coupled with climate changes resulting to increased to both hydraulic and pollutant loads poses as daunting challenge in meeting present and future stringent discharge compliance limits. Treatment capacities – operational modes • Dry weather flow 1450 l/s or approx. 125.000 m3/d – it is subjected to biological and chemical treatment with filtration as final step (max capacity 1900 l/s) – • Flow rates between 1900-4000 l/s is treated chemically and partly filtration (< 3000l/s) – • Nitrogen, phosphorus and organic matters are removed Phosphorus is removed and organic matters is partly removed Flow rates between 4000 - 6000 l/s is treated through 3 mm screens: Objects such – Objects such as rags, paper, plastics, and metals are removed Wastewater treatment process- Flowchart PAX-18 Primary Precipitation Magasin~35.000m3 Oslo fjord Q<1900 l/s Primary Sand, grit and screenings Q=1900 l/s Clarifier Activated sludge Filter FeSO4 Sludge recycle 4000 l/s < Q < 6000 l/s Biogas Bio sludge Thickener Primary sludge Buffertank Belt Thickener Digester Silo Digester Biogas Upgrading Plant Dewatering Silo Overflow PAX-18 Mixed liquor recycle 1900 l/s<Q< 4000 l/s Buffer Nitrogen removal – Biological treatment processes Influent Sewage Organic nitrogen - Urea Ammonia nitrogen NH4 O2 Nitrification 1st Step Nitrate N0-2 2nd Step O2 Nitrate N0-3 Denitrification Organic carbon (carbon source) Nitrogen gas N2 Sludge treatment process Thickening Reduces the content of water in sludge to reduce hydraulic load on the digesters. Primary sludge thickened in belt thickener with polymer Bio sludge thickened in centrifugal thickening with polymer Digesters Thermophilic anaerobic digestion process, whereby the incoming sludge is pre-heated before entering the digesters Digestion in the digesters , at 55 °C in 15 days Dewatering Reduces the content of water in sludge to reduce transport costs Centrifugal dewatering with polymer (30-35% DS) Sludge storage tanks Acts as buffer in order to obtain uniform loading of the system and stores sludge during unexpected failure system. Sludge Production Generated at the plant is approximately 5500 -6000 tons DS/yr Facts and Goals for the City of Oslo. CO2 emissions from private and public transport is approximately 50- 80% of the total emissions in the city of Oslo. The City of Oslo’s main goal is: To cut 50% of greenhouse emissions by the year 2030. LP COOAB ® process – Low Pressure CO2 Absorption CO2 absorption Gas drier Gas tank High pressure compressor Activated coal - filter 200 bar CO2 0,5 bar 2 bar CO2 removal/ COOAB recovery Odorizing the biomethane Produced upgraded biogas (biomethane) 2,500,000 2,000,000 1,99 mill. 2,05 mill. Nm3 Nm3 2012 2013 1,44 mill. Nm3 1,500,000 1,04 mill. Nm3 Nm3 1,000,000 500,000 0 2010 2011 17 Biomethane value chain Producer End Biomethane Money flow 18 Exhaust emission and noise S/N Units Diesel Bio-methane Reduction % NOx g/km 8.1 1.9 78 Particulate matter g/km 0.3 0.005 98 CO2 kg/km dBA 2.6 111 0 100 100 92 Noise Oslo kommune Vann- og avløpsetaten The potential of Biomethane in Oslo Oslo: 600 000 p.e. 10 – 12 million Nm3 biomethane Buses Personal vehicles Sewage sludge 150 – 200 6 000 Household organic waste 200-250 8 000 Total 350 - 450 14 000 62 64 66 240 1100 2000 Source: AGA-Linde Net Energy production Net energy production: 21-14-5-0,2 =1,8 GWh/yr 20 15 14 10 5 5 0.2 0 Electricity GWh -5 Pellets Oil Upgradert biogas (biomethane) -10 -15 -20 -21 -25 Green Emission for chemical consumption Greenhouse emission ton CO2/yr 900 Greenhouse emission from chemical consumption = 1195 ton CO2/yr 800 775 700 600 500 400 300 300 200 100 50 45 25 Polymer Lime Iron sulphate 0 PAX18 Ethanol Total Greenhouse Emission Totale Green Emission 3200 - 6400 = -3200 ton CO2/yr 3000 2000 1800 1195 85 90 Pellets Oil -2000 -3000 -4000 Biomethane -1000 Chemical consumption 0 Electricity CO2 emission ton CO2/yr 1000 -5000 -6000 -7000 -6400 Challenges facing Bekkelaget WWTP This include among others; Population growth in Oslo is taxing Bekkelaget wastewater treatment Plant and creating a need for new plants. Oslo will have in the range of 1.1 million inhabitants (including Nittedal municipality) in 2020. This represents a population increase of 18-25% since 2009 (Figure). Bekkelaget WWTP was dimensioned for 270 000 p.e. in 2000, in 2013, Bekkelaget serves 331 000 p.e. Climate change – Many of the earliest sewer systems were combined sewers, designed to collect both sanitary wastewater and storm water runoff in a single system. Increased Hydraulic Loads hence increased pollutant loads (NTot and PTot ). Stringent discharge consent for 70 % Nitrogen and 90 % phosphorus removal including overflow and the total amount of overflow must be less than 2% of the total loads of nitrogen, phosphorus and organic matters Expansion of Bekkelaget WWTP THANK YOU FOR YOUR ATTENTION!