Japanese urbanization and domestic wastewater management December 15 th, 2010 WEPA Dialogue in Nepal Takatoshi Wako Deputy Director, Water Environment Division Environment Management Bureau,, Japan
Night Soli Recycling Systems in Edo Era A sanitary city unlike any other in the world, where organics substances such as night soil and garbage were reused as suppliers of fertilizer in outlying farming village Less epidemics in Japan comparing to modern Europe A farmer carrying tubs of night soil Night soil recycling systems in Edo Era Source: Annual Report on the Environment 2
From Edo to Tokyo Population increase and Start of sewerage construction Outbreak of the Pacific War (1941) Oil price shock (1973) End of Edo Era (1867) Rapid economic growth Started (1955) End of the Pacific War (1945) Transit of population in Tokyo Yokohama: Brick-made sewer line (1881) Tokyo: Mikawa-jima Sewerage Disposal Plant (First sewerage disposal plant in Japan:1922) 3
History of Sanitary Treatment of Night Soil in Japan Storage of night soil and utilization for agriculture(1200s~1960s) Decreasing demand for the traditional night soil recycling systems due to the urbanization and the spread of chemical fertilizer (1950s) Nationwide water pollution caused social problem(the late 1960 s~) Trends of waterborne disease rates in Japan 4
Water Pollution of Tokyo in 1970 s Tokyo Bay in 1970 s A river of Tokyo in 1970 s The Kanda river (Tokyo) in 1970 s Photo Credit : Environmental Bureau of the Tokyo Metropolitan Government 5
Night Soil Treatment and Domestic Wastewater Treatment Systems in Japan 6
System of Sewerage Projects Based on the Sewerage Service Act. Purpose of the Projects Sound development of cities, prevention of floods, securing of public sanitation, and water quality preservation in public water areas Implementation system National government: Approval of project plans, subsidization, etc. Prefectures: Construction and management of river-basin sewerage Municipalities: Construction and management of public sewerage Plans on sewerage Comprehensive plan on river-basin sewerage construction Plans of prefectural governments: Master plans for deciding appropriate wastewater treatment methods Plans on measures against rainwater Sewage sludge treatment comprehensive plan Financial system Financial system of sewerage projects based on governmental subsidies, user s fee, etc. 7
Mechanism of Japan s Sewerage Combined sewerage Adopted in Japan because urgent issues in the past were flood prevention and improvement of living environments in big cities like Tokyo where sewerage construction had been started since early times Separate Sewerage Adopted since water quality preservation in public water areas was defined as one of the goals in the Sewerage Service Act was revised in 1970. Sidewalk Road Sidewalk Road Wastewater and Rainwater Combined sewerage Wastewater Separate sewerage Rainwater 8
River-basin Sewerage and Public Sewerage Public Sewerage (constructed by municipal governments) River-basin Sewerage (constructed by prefectural governments) Public Sewerage Public Sewerage Sewage treatment plant Public Sewerage B City D City A City C City Public Sewerage River-basin Sewerage Sewage treatment plant 9
Johkasou as Decentralized Treatment System Advanced domestic wastewater treatment system (tank) developed in Japan Cost-effective in decentralized area (Low initial investment cost) Little topographic limitation, short installation time Invaluable contribution to maintaining sufficient water in small rivers Less vulnerable to disasters Johkasou (Anaerobic filter contact aeration type) 10
Treatment Principles and Types of Johkasou Designed for treating both black water and grey water Wastewater are broken down biochemically by the catabolism of microorganisms such as bacteria and metazoan organism Structure and treatment principle of Johkasou 11
Legislative Systems for Johkasou (Johkasou Law) Background of legislation Water pollution and degradation of living environment caused by improper construction and maintenance of Johkasou Objective To promote the appropriate treatment of domestic wastewater, to maintain good water quality of public water bodies and a healthy living environment, and to improve public health Main contents of Johkasou Law Notification of installation of Johkasou Regulations on construction, installation, operation and maintenance, desludging and examination Qualification and licensing of technician and operators 12
Operation, Maintenance and Inspection of Johkasou Inspection after construction Annual inspection 13
Comparison between sewerage treatment system and Johkasou Sewerage treatment system Johkasou Function Wastewater treatment and Prevention of inundation Wastewater treatment Object Treating wastewater collectively Treating wastewater Individually Suitable area Urban area Area of scattered population Administrator Municipality Individual or Municipality Useful life of facility Treatment plant : 15-70 years Piping system : 50-120 years main body : over 30 years equipment : 7-15 years 14
Plans of Prefectural Governments For efficient construction of wastewater treatment facilities in each region, a construction plan for wastewater treatment facilities has been formulated based on comparison of economic efficiency, etc., considering the characteristics of each wastewater treatment facility. Cost per family (construction, operation& maintenance) Equilibrium point Individual treatment(johkasou) Mass treatment(sewerage) Population density Individual treatment (Johkasou, etc.) is better Mass treatment (sewerage, etc.) is better 15
Population Trends for domestic wastewater treatment Self-management night soil area Night soil collection Sewerage systems Johkasou Population Trends for night soil treatment and domestic wastewater treatment 16
Wastewater management one of the 2 nd phase WEPA s theme Target To analyze each country s situation, challenges, and policies on domestic wastewater management, which is common issues for improving water environment To propose improvement strategies corresponding to challenges What we do this year Conduct questionnaire investigation on each country s; Current situation and challenges on domestic waste water Representative points where water environment has been worsening Good practices of domestic water treatment by local communities etc. 17
WEPATechnology Database Wastewater treatment facility in operation for more than 3 years 218 Data from 9 countries Categorized by Type of your treatment Type of wastewater Countries 18