28 Feb 2012 ... Japan Education Center of Environmental Sanitation. Aizawl, INDIA ... Night Soil
and Domestic Wastewater Treatment Systems in Japan. 2 ...
Japan’s Experience in Decentralized Sanitation (Johkasou) Decentralized Sanitation (Johkasou) Xinbi Yang Japan Education Center of Environmental Sanitation
Aizawl, INDIA 28 Feb. 2012 1
Night Soil and Domestic Wastewater Treatment Systems in Japan
2
Population Served by Different Systems Population Served by Different Systems
14%
Sewerage system Rural sewerage system Johkasou system Night soil treatment
9% 74%
3%
(as of the end of FY 2009)
100 90
(as of the end of FY 2009)
99.4
90.3
88.9
84.5
80
Perrcentage, %
70
78.0 71 0 71.0
S off major Sum j domestic d ti wastewater t t ttreatment t t systems t
60 50 40 30 20 10
0.5
5.9
7.5
9.6
300-500
100-300
16.9
13.9
Johkasou system
0 More than 1,000
500-1,000
50-100
Less than 50
Size of municipalities, thousand people 3
Number of Installed Johkasou Johkasou:2.9 million units Tandoku-shori johkasou:5.45 million units (as of the end of FY 2009)
65.3% 34.7%
A small-scale johkasou 4
Advantages Ad t off JJohkasou hk System S t for f Decentralized Treatment Low initial investment cost Little topographic limitation, short installation time and early realization of the effects Invaluable contribution to maintaining sufficient water in small rivers and aquatic environments near inhabited areas Johkasou-treated water and sludge are easy to reuse Less vulnerable to earthquakes and other disasters
5
Pollutant Loads for Johkasou Design
Determination of Johkasou Size in Buildings Classified by Purpose of Use (Examples) JIS A 3302 2000