Wastewater Sludge Recycling/Reuse in Japan

Transcription

1 Wastewater Sludge Recycling/Reuse in Japan Workshop on Urban Fecal Sludge Management 23rd February 2010, Hanoi, Vietnam Takehiko Kawai Director

2 Classification of Sewage Treatment Processes in Japan As of the End of FY 2006

3 Amount of sewage sludge (thousand dry-solid ton) Recycle ratio (%) Recycling of Resource and Energy from Sewerage Recovery of Resource and Energy from Sewerage Sludge, in order to ensure stable treatment and to solve Global Warming Amount of Sewerage Sludge Production 2,500 2,000 1,500 1, Other Recycle ratio of Sewage Sludge Fertilizer Landfill Cement Bricks, tiles Fuel Fiscal Year 3

4 Land fill site

5 Tree Chart of Sludge Resources

6 Tree chart of sludge resources Publicity Tool LEGEND

7 Sludge Utilization: Compost Piled type composting Horizontal shovel type Sludge compost products

8 Quality of product (3) Heavy metals and other undesirable substances Fertilizer management law Waste disposal and Cleaning law Dioxin management law Management standard for prevention of Heavy metal accumulation in soil for agriculture Law for prevention of agricultural land contamination (Note) Environmental standard for soil contamination Content Elution amount Content Content Content Elution amount Alkilmercury ND ND Total Mercury 2 mg/kgds 0.005mg/l 0.005mg/l Cadmium 5 mg/kgds 0.3mg/l 1mg/kg-rice 0.01mg/l Lead 100mg/kgDS 0.3mg/l 0.01mg/l Organic Phosphorus 1mg/l ND Chromium (Ⅳ) 1.5mg/l 0.05mg/l Chromium 500mg/kgDS Arsenic 50mg/kgDS 0.3mg/l 15mg/kgDS 0.01mg/l Cyanogen 1mg/l ND PCB 0.003mg/l ND Copper 125mg/kgDS Zinc 120mg/l Nickel 300mg/kgDS Selenium 0.3mg/l 0.01mg/l Dioxin 3ng-TEQ/g 1ng-TEQ/g Official standard for Official standard for for Ash, Slag, Standard for Only for paddy field normal fertilizer normal fertilizer etc. Soil itself Standard for soil itself The titles of the laws mentioned above are not the full titles.

9 Thickening Digestion Dewatering Supernatant Dried and composted sludge Drying Incineration Carbonization Sintering Utilization for agriculture and greenery

10 China Town in Yokohama City Incineration ash

11 Recycling of Resource and Energy from Sewage Gifu Prefecture Phosphorus recycling system Kobe-city Tokyo Fertilizer produced from sewage sludge is used for the production of vegetables in Gifu, and the vegetables are famous for their excellent quality. Solid Fuel Biogas Station Biogas Refinery Carbonization of Sewer Sludge Electric Power Generation 11

12 Problems with Digestion Gas Waste Gas Burner Desulfurizer Digestion Tank LP Gas Tank Boiler for warming Digestion Tank Malfunctioning by Siloxane Problems for utilization 1 Warming facilities and gas tank are corroded by digestion Gas which contains hydrogen 2 Digestion gas which contains Siloxane creates problem by crystallization to warming facilities and gas blower. 3 Methane concentration is approximately 60%. Consequently, heating capacity is lower with about half of the capacity of the city gas.

13 Refining Digestion Gas to Bio Natural Gas 2004 Kobe city Kobelco Eco-Solutions Refining Digestion Gas to Natural Gas (Joint Research) 2005 Public Works Research Institute Gas refining system Refining Digestion gas to Natural Gas and commercialization for car fuel (joint Research) Kobe City Kobelco Eco- Solutions Kobe Bio Gas Station

14 solubility Refining System of Digestion Gas (water scrubbing process flow) Sewage Sewage treatment Treated WW Kobe Biogas Kobe Biogas Station Digestion tanks Sludge Treated WW Scrubber Treated water P u m p To treatment system Low pressure tank Solubility-difference (CH4 and CO2) pressure Water pump Compressor

15 Effective use of Kobe Biogas Vehicle for officials Truck for sludge cake Taxi Kobe city bus Garbage wagon Home dispatch Drain pipe sweeping machines

16 Project: Pouring into the City Gas Actual proof facility of Pouring into the city gas. Properties Unit Digestion Gas (Pre-Desulfurization) Kobe Bio Gas Acceptance standard value by Osaka Gas Methane Vol% Carbon dioxide Vol% Oxygen Vol% Nitrogen Vol% Hydrogen Sulfide ppm 330 < Siloxane mg/nm 以下 - High rank calorific value MJ/Nm Smell mg/nm ~16

17 Networking of renewable biomass energy Agriculture Green Foods Water Wastewater System Kobe city Water Reclamation Energy- Regenerating

18 Study on Economical Biomass Methane Fermentation in Small City by Suzu City and JIWET (Japan Institute of Wastewater Engineering Technology) The most important issue for sewage sludge treatment is the increase of treatment cost. Suzu City, which is located in a coastal area, expects to face an increase of cost for its sludge treatment. Suzu City is therefore promoting waste recycling by combining sewage sludge with other biomass and raw garbage from businesses to obtain methane fermentation. By using biogas energy to dry sewage sludge for utilization as a fertilizer, Suzu City expects to realize important cost saving for sludge treatment and other biomass treatment. The facility specifications were decided in The facility performance has been evaluated since the time it went into operation in 2007 to The purpose of this study is to evaluate the effects of such facility.

19 Location of Suzu City Methane fermentation Dryer Control building Sludge treatment building 1/2wastwater treatment Heating building 2/2wastwater treatment 消毒施設 Gas tank Machine building Photo.1 Biomass methane fermentation treatment plant in Suzu City.

20 Sludge treatment flow in Suzu City Wastewater Influent Oxidation ditch Final sedimentation tank Discharge Sewage sludge Thickening tank Sewage sludge from wastewater treatment plant in rural area. septic tank sludge Machine building Receiving tank Receiving &mixing tank Screen Storage tank Thickening facility Methane fermentation tank Gas holder Heating Night soil Garbage Receiving tank Receiving hopper Screen Storage tank Mixing tank Dewatering Boiler for Machine heating Crushing & Solubilization tank Heating separation Drying Storage tank Dryer Legend Biomass, Biogas, Energy Dried sludge Free distribution Figure 1 Schematic diagrams of biomass methane fermentation treatment facility

21 Possibility of utilizing dried sludge as a fertilizer The results of a pot test show no hindrance for plant growth with dried sludge. It was also confirmed that dried sludge is thoroughly useful as a fertilizer. Drying conditions has shown and confirmed that dried sludge meets EPA standards and is totally safe for health. Photo.2 Results of a pot test showing no hindrance to plant growth by dried sludge. Photo.3 Dried sludge.

22 Life ycle cost(lcc) and life cycle CO2(LCCO2) impacts centralized treatment. 60,124 Construction cost Utility cost Driving management consignment expense Disposal cost 40,633 49, ,881 (77%) Individual treatment 68,662 55,377 47,000 23, ,054 (100%) 0 50, , , , ,000 Cost during year( /year) Fig.1 Comparison of LCC Amount of construction exhaust Amount of driving exhaust Amount of update exhaust Amount of abandonment exhaust centralized treatment. 5,525 12,284 2, ,187 (96%) Individual treatment 2,402 17,066 1, ,975 (100%) 0 5,000 10,000 15,000 20,000 25,000 CO 2 exhaust (t-co2) Fig.2 Comparison of LCCO 2