Advantages of Japanese on-site treatment system

Transcription

1 Advantages of Japanese on-site treatment system - The history of night soil treatment in Japan - Akira Morita Japan Sanitation consortium/ Japan Environmental Sanitation Center

2 History of Sanitation in Japan ~1950s : Agricultural use Human waste was collected and recycled as a fertilizer for rice farming before the diffusion of chemical fertilizer in 1940s. 1950s ~ : From Valuable Material to Waste Worsening of Environmental Pollution Spread of Hygienic Disposal Establishment of Institutions for Environmental Sanitation. 1980s~ : Sustainable Development Recycling (Energy&Biomass) Global Warming (Energy saving) 2

3 Major systems for night soil and grey water treatment Night soil+grey water Wastewater treatment facility Night soil (Vault and vacuum toilet) 3

4 Population, million Population trends for on-site & off-site sanitation systems in Japan Vault toilet + Night soil treatment plant Disposal to the nature without treatment Dumping into the sea Public sewerage system Year Development of human waste management in Japan ( ) 4

5 History of Technology Innovation for Night soil Treatment In Japan Innovative level of technology Anaerobic Digestion Prevention from diseases Aerobic Digestion Pollution Control Denitrification Process Environmental Protection High-rate membrane Process Energy & Biomass recycling Removal of N P Elimination of Foul air, COD & Color Hygienic Sanitation and Removal of SS BOD High efficiency & Compactification Sludge Treatment system with recycling Resources Reclamation s 80s 90s After

6 History of Technology Innovation for On-site Treatment in Japan Innovative level of technology Packaged Aerated Wastewater Treatment Plant (PAWTP Johkasou) Low Technology (Anaerobic treatment) Flush toilet water Flush toilet water Oxidation Bed Process (Black) Eff. <BOD 130mg/L 1950 PAWTP (Black water only type) Eff.<BOD 90mg/L Fig. 1 Flush toilet water 1970 Flush toilet water & Grey water PAWTP Soil trench process (Black) Eff. <BOD 20mg/L (Both black + grey water type) Unit-type Eff.<BOD Small-scale 20mg/L Medium-scale (5~50 (<T-N 20mg/L) 人程度 ) (50~500 人程度 ) Fig. 2 Fig Fig. 4 6

7 Classification of on-site treatment technology system in Japan Floating organism method Activated sludge process Contact aeration process Rotating biological contactor process Natural method Soil trench, (Wetland) Vault toilet method Vault and vacuum toilet Urine/Feces separating compost toilet PAWTP (Johkasou) Mountain/Park toilet Mountain toilet

8 PAWTP (Johkasou) system in Japan Night soil (O&M) (Desludging) (Transport) Night soil/sludge Treatment Facility Unit-type Plant-type Plant-type Effluent: Unit-type <BOD20mg/L Plant-type Small-scale Medium-scale Medium/Large-scale Small-scale Medium-scale Medium/Large-scale Small-scale Medium-scale Medium/Large-scale (5~50 人程度 )) (50~500 人程度 ) ) (500 (500 人程度以上 ) ) (5~50 人程度 ) (50~500 人程度 ) (500 人程度以上 ) Unit type: 5-50PE Unit type: PE Plant type: >500PE 8

9 What is PAWTP (Johkasou)? Advanced domestic waste water treatment system (tank) developed in Japan Treats wastewater as clean as BOD 20mg/L Treats not only black water but also grey water Operated for 11 million Japanese people in less populated areas around Japan, as a technique which is cost effective and able to be installed in a short time. 9

10 Number of PAWTP (Johkasou) Number and Trends of installed PAWTP (Johkasou Both black and grey water type) 4,000,000 PAWTP (Johkasou Both black and grey water type) Number of PAWTP 3,333,623 3,500,000 3,000,000 2,500,000 2,000,000 1,500,000 1,000, ,000 Johkasou Act (effective in 1985) National subsidy program (Johkasou installation promotion) National subsidy program (Municipal Johkasou installation) Revision of Johkasou Act Revision of Johkasou Act Year 10

11 Outline of On-site Technologies On-site technology Advantages Disadvantages Pit latrine -Water and electricity are not required. -Unsanitary Composting toilet -The installation cost is inexpensive. -Water and electricity are not required. -Turn to soil of farmland -Groundwater contamination -Difficult without agricultural demand Septic tank Johkasou -Flush toilet is possible. -Electricity is not required. -Less sludge production -Environment-friendly -High treatment performance -Measures against colon bacillus contamination is possible. -Secondary treatment is required. -Limitation in treatment performance -Source of colon bacillus contamination -Electricity is required. -More sludge production

12 Performance of septic tank system Effluent water quality Sludge generation 0.17L/PE/day (Source: JICA) Properties of Septage (Source: Hidenori Harada) COD Cr BOD SS T-N T-P (mg/l) Average Range Source: USEPA(Black+Grey) 12

13 Variety of sludge treatment method (1/3) - Integrated Processing in Sewage Treatment Plant - Receiving facility for sludge from on-site treatment facility Method-1 Flow Sheet Sewage Treatment Plant Excess Sludge Sewage Treatment Process Bar screan unit Homogenised Super natant Vacuum truck Receiving tank p Aeration strage tank Pump pit p sludge Sludge strage tank (Expansion) p Dehydrator Dehydrated sludge Disposal 13

14 Variety of sludge treatment method (2/3) - Integrated Processing in Sewage Treatment Plant - Receiving facility for sludge from on-site treatment facility Receiving Method-2 facility Flow for sludge Sheet from on-site treatment facility Method-2 Flow Sheet Sewer treatment plant

15 Variety of sludge treatment method (3/3) - Independent Sludge Treatment Plant - 15