Japan’s Experience in 

Decentralized Sanitation (Johkasou)Decentralized Sanitation (Johkasou)

Xinbi YangXinbi YangJapan Education Center of Environmental Sanitation

Aizawl, INDIA28 Feb. 2012

1

Night Soil and Domestic Wastewater Treatment Systems in Japan

2

Population Served by Different SystemsPopulation Served by Different Systems

Sewerage system

9%

14%

Sewerage systemRural sewerage systemJohkasou systemNight soil treatment

9%

3%74%

(as of the end of FY 2009)99.4 90.3 88.9

84.578.0

71 0 8090

100(as of the end of FY 2009)

S f j d ti t t t t t t 71.0

3040506070

rcenta

ge, %

Sum of major domestic wastewater treatment systems

0.55.9 7.5 9.6 13.9

16.9

0102030

More than 1,000

500-1,000 300-500 100-300 50-100 Less than 50

Per

Johkasou system

3

1,000

Size of municipalities, thousand people

Number of Installed Johkasou Number of Installed Johkasou

Johkasou：2.9 million unitsTandoku-shori johkasou：5.45 million units

(as of the end of FY 2009)

65.3%34.7%

A small-scale johkasou

4

A small-scale johkasou

Ad t f J hk S t f Advantages of Johkasou System for 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 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 Determination of Johkasou Size in Buildings Classified by Purpose of Use (Examples)

JIS A 3302 2000

Structure and Treatment Performance of Johkasou

Treatment Principles of JohkasouTreatment Principles of Johkasou

9

A small-scale Johkasou (FRP)A small scale Johkasou (FRP)

Effluent water qualityBOD <=20 mg/l

Diffusion pipe

Anaerobicfilter tank

Contactaerationtank

Sedimentationtank

Disinfectiontank EffluentInfluent

tank

Separatedsludge

Sludge10

Filter Media Used in JohkasouFilter Media Used in Johkasou

A Johkasou for BOD&N RemovalA Johkasou for BOD&N Removal

Intermittent pump

Pipe for recirculation

Disinfectiontank

p p

Anaerobic filter tank(1st room)

tank

(1st room)

Anaerobic filter tank( d )

Effluent water quality

BOD <=20 mg/l(2nd room)

Contact Aerationtank

Sedimentationtank

Diffusing pipe

T‐N <=20 mg/l

recirculation

Anaerobicfilter tank

Contactaeration tank

Sedimentationtank

Disinfectiontank Effluent

recirculation

Influent

Flow equalization Sludge12

A J hk f BOD&N&P R lA Johkasou for BOD&N&P Removal

【制御ボ クス】【防水コンセント】

リン除去装置

＜槽外設置＞

C t l

Cell base

Cell base

Cell base

【中継ボ クス】

【制御ボックス】【防水コンセント】

【電源ケーブル】

槽

Controler

C ll b

Cell base

Cell base

防水コネクタ【中継ボックス】

【セル】

＜槽内設置＞ Connecters Relay boxCell base

Cell base

鉄電極

セルベース固定ボルト

Electrodes

Cell baseBolts

Effluent water quality

BOD <=10 mg/lBOD <=10 mg/lT‐N <=10 mg/lT‐P  <= 1 mg/l

13

A Membrane JohkasouA Membrane Johkasou

Effluent water qualityBOD <=  5 mg/lT‐N <=10 mg/l

14

Johkasou classified by the treatment capacityJohkasou classified by the treatment capacity

• Small-scale johkasou: for 5 to 50 NUD , or the average j , g

amount of wastewater less than 10 m3/day.

• Medium-scale johkasou: for 51 to 500 NUD, or the average

amount of wastewater less than 100 m3/day.

• Large-scale johkasou: for 501 NUD or more, or the

average amount of wastewater more than 100 m3/dayaverage amount of wastewater more than 100 m3/day.

NUD: number of user for design

I t ll ti O&M d D l d i f Installation, O&M and Desludging of Johkasou system

Operation＆Maintenance

Installation

Operation＆Maintenance

Desludging16

Legislative Infrastructure Underpinning Legislative Infrastructure Underpinning Johkasou Systems

17

O ti M i t d Operation, Maintenance and Inspection of Johkasou

Framework of johkasou management under the Johkasou Law18

Construction of JohkasouJohkasou

19

Details of Operation, Maintenance and I ti f J hk Inspection of Johkasou

20

Johkasou Technicians and VendorsJohkasou Technicians and Vendors

(As of the end of FY 2007)

21

S b id P f J hk I t ll tiSubsidy Programs for Johkasou Installation

22

•Johkasou has economical advantages and is effective for decentralized sanitation in areas of low population density.decentralized sanitation in areas of low population density.

•Johkasou is a system including hardware (treatment plants)and software (O&M inspection under a legal framework)and software (O&M, inspection under a legal framework) .The latter issues is much more important in decentralized sanitation.

•The experience of Japan in decentralized sanitation with johkasou is useful and applicable to other countries as a j ppprevalent measure of sanitation.