Lesson Learnt from Japan’s Experiencefrom the perspective sustainability
on domestic waste water management
Bangkok, Thailand
December 2 2014

Office for Promotion of Johkasou
Waste Management and Recycling Department
Ministry of the Environment
JAPAN

Ministry of the Environment1

Outline
1. Japanese Johkasou
2. Implementation of construction ofwastewater treatment facilities in japan
3. Difficultly of change from existing Tandokushori Johkasou to new Gappei-shori
Johkasou
4. Importance of maintenance of johkasou
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NIGHT SOIL AND DOMESTIC WASTEWATER TREATMENTSYSTEMS IN JAPAN4

Advantages of johkasou
High treatment performance
Johkasou can treat wastewater like sewage treatment
plants（BOD ≦20mg/l, BOD removal rate ≧ 90%) by the
catabolism of microorganisms . There is nitrogen and/orphosphorous removal type.

Little topographic and early realization of theeffectAs small-scale johkasou can be installation in a small,space equivalent of a parking spot and be lessrepresented for underground. It takes only a week fora typical installation. Moreover, when the johkasou
begins functioning, its effect is evident immediately.

Less vulnerable to earthquakes or other disasters
As it has not a complicated piping system, johkasou is lessvulnerable to earthquakes and other disasters.
※ According to the results of a survey on the Great East Japan

Earthquake, completely destroyed johkasou is 3.8％（researching of1099 unites in over intensity 6 lower or hitting by tsunami area）

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The coverage of domestic Wastewater Treatment Facilities
・The ratio of people using domestic Wastewater Treatment Facilities （2013）100（平成２５年度末）

99.5%
93.1%

92.0%

下:86.8%

下:83.4%90

下:99.0%

汚水処理人口
普及率
全国平均：88.9%

88.0%
下:75.6%

下:62.9%80

Not diffusion １１ ％82.5%

普75.6%
下:48.7%70

汚水処理施設（全体）60Rate of waste water
treatment population
national average88.9%

Sewerage system: ７７%

及50

40
率
30

コ:0.5%
農:8.1%

20

Johkasou: ９%

農:4.6%

(%)
100
人口規模

Rural sewerage system: ３%

農:1.0%

農:2.7%

浄:7.4%

浄:9.5%

30～50万人

10～30万人

農:0.5%
浄:0.3%
100万人以上

big

浄:5.6%
50～
100万人

City population

浄:14.7%

5～10万人浄:18.3%

5万人未満

small

The ratio of Johkasou is high in municipalities with small population
67

Population trends for wastewater treatment［Million People］

140
120
100
8060

Total population
Population in flush toilets
Population in sewage
Population in johkasou

40
20
0

1980

1985

1990

1995

2000

2005

2010

By 1940’s, night soil was used for agriculture in Japan.
With the rapid economic growth, the pollution occurred by water contamination.
Sewerage Service Act was established for sound development and improvement ofpublic health in urban areas.
As a result population in flush toilets were included every year.
8Trends of sewage outstanding debts issue［Million Yen］

Source: Handbook of sewerage management 2012

35,000,000
30,000,000

Amount of debts

25,000,000
20,000,000
15,000,000
10,000,000
5,000,0000

1966 1970 1975 1980 1985 1990 1995 2000 2005 2010
Sewage outstanding debts issue is increasing with implementation of sewage
treatment facilities.
As sewage pipes have been getting older and renewal of piping system has
already started, the cost will increase in the future.
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Manual for planning of wastewater treatment
facilities in prefectures• This manual provides

Per Capita Cost (incl. constructionand maintenance cost)• Manual for municipalities incharge of wastewater
treatment(especially on-site system)

Cost comparison of centralized system andon-site system

Johkasou

Balance point

On-site system
Centralized system
Population density

Rural seweragesystemSewerage network•basic concept to create efficient and economic plan of wastewater
treatment systems•the way to make a rough estimate of constructing and O&M cost ofwastewater treatment systems•method for economic comparison of various wastewater treatment
systems•Includes standard data such as construction cost, maintenance cost, usefullife of the systems
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Replaceing Tandoku-shori Johkasou (black water only)
By Johkasou (black and gray water)

Johkasou

There arefew pollution

Public waters
Tandoku-shori
JohkasouPollutant load is 8 timesof Johkasou’s

untreated

・Pollutant load from Tandoku-shori johkasou is 8 times of that of Gappei-shori Johkasou.
・There is no duty for house owner to replace Tandoku-shori Johkasou by Johkasou.
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New installations of Tandoku-shorijohkasou were banned from 2001
Work hard andcover my part too!

Just leave it to me

Tandoku-shorijohkasouJohkasou13

Number and trends of installed Johkasou
Bannning
Tandoku-shori
Johkasou

10,000,000■Tandoku-shori Johkasou (black water only)
9,000,000■Johkasou (Black and gray water)

8,000,000

Number of Johkasou

7,000,000
6,000,000

Number of Johkasou
7,758,986 (Total)

Revision ofJohkasou Act
Johkasou Act(effect in 1985)

Revision ofJohkasou Act

Tandoku-shori
Johkasou
4,531,552
58%

5,000,000
National subsidy
program (Municipal
Johkasou installation)

4,000,000
3,000,000
2,000,000

National subsidy
program (Johkasou
installation promotion)

Johkasou

3,227,434
42%

1,000,000
083 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 00 01 02 03 04 05 06 07 08 09 10 11 12

・To accommodate a flush toilet request, Tandoku-shori jhkasou were constructed.
・Johkasou law amendment in 2000, new construction of Tandoku-shori johkasou
is inhibition
・Tandoku-shori johkasou banning installation is remained about 4.5 million （60%）
・For long durable years, moving ahead changeover to gappei-syori johkasou is slowly.

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Johkasou maintenance in Japan≪Inspection of after starting use
the johkaosu≫

Three to eight months
after starting
operationLegal inspection
by Article 7
Confirm if theconstruction/installationand treatment
performance are goodat the beginning.

≪maintenance and inspection in using johkasou≫

Over three times ayear, depending on
the size and thetreatment process

Once a year

Once a year

Operation/
maintenance

Desludging

Legal inspection
by Article 11

Recover normal
treatment performance

Confirm if themaintenace anddesludging is conducted
appropriately, and if
the treatment
performance is good.

Maintain a normal
treatment performance・visual inspection

・sludge accumulation

・water quality inspection・mechanical apparatus

・document inspection

・replenish disinfectant

・removing sludge
・cleaning the johkasou
・confirming if there are
faults or defects inside
the johkasou

Specified inspection
agency, which is a public
service corporation of theprefecture.

Johkasou maintenancevendor, which islicensed by theprefectural governor

Johkasou desludging
vendor, which isregistered by themayor

・visual inspection
・water quality inspection
・document inspection
Specified inspection
agency, which is a public
service corporation of theprefecture16

Effluent Water quarity of Johkasou
For applicable maintenance doing,
・838,349unites(85.0%) of johkasou is BOD<20mg/l
・generality johkasou performance is equivalent to sewage
Under 60mg/L
6%Under 30mg/L8%
Under 20mg/L8%

Over 60mg/L
2%

Under 5mg/L
37%
Under 15mg/L
13%
Under 10mg/L
26%※By Johkasou administrative organization research in 2013
・Johkasou structural criterion is BOD>20mg/L, 986,643 units
・Inspection result of Legal inspection by Article 11 in 201317

CONCLUSIONS
１．With the implementation of sewerage systems, the government has
been faced with various problems, especially on the financial aspects.
→It is preferable to select centralized or decentralized treatment
efficiently according to the local situations.
２．The progress of replacement of existing tandoku‐shori johaksou bygappei‐shori johkasou is a littte .
→ It is preferable to install gappei‐shori johkasou rather than tandoku‐
shori johkasou when start to implementation of wastewater treatment
facilities.
３．O&M is the key issue to make johkasou in normal condition.
→To ensure water quality of treated water, it is necessary to make aframework to confirm whether the O&M is conducted appropriately.
18Thank you foryour attention!
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