Introduction of Japanese Johkasou
31th January, 2024

Mr. Ryoma SATO
Section Chief, Office for Promotion of Johkasou

Office for Promotion of Johkasou
Waste Management Division
Environmental Regeneration and Material Cycles Bureau
Ministry of the Environment
Government of JAPANhttps://www.env.go.jp/recycle/jokaso/

Water pollution in Japan during rapid economic growth

Dohkai Bay(Kitakyushu)
in the 1960s

SumidaRiver(Tokyo)
in the1970s

Chofu Weir,
Tama River(Tokyo)
in the 1970s

2

History of wastewater treatment and infectious diseases
 Up to the 1950s, night soil had been used as agricultural fertilizer and regarded as resource.
 From the late the 1950s, night soil had become “waste” due to the spread of chemical fertilizers andurbanization. Lack of night soil treatment facilities and hygienic treatment had become serious social problems.
 Spread of infectious diseases had continued until the rapid economic growth period of the 1970s.

(3) Yuzo Inoue, History and technology of night soil treatment in Japan, J. of Monthly Johkasou

3

Domestic wastewater treatment issues in Japan

Late 1950s to around 1970

Late 1970s to 1980s

PresentWater pollution is aserious environmental
problem

Domestic wastewater
caused localizedpollution

Resolved andprevented the spreadof water pollution

Widespread use of flush toilets

Mainly caused byfactory wastewater4

Achievement of water quality related to Effluent Standards

100Rivers 93.1%
Total 88.3%

90

Seas 78.6%

Achievement rate (%)

80
7060

Lakes 53.6%

5040

Measuring item
Rivers：BOD (Total 2,577 water-area)
Seas： COD (Total 590 water-area)
Lakes： COD (Total 192 water-area )30
201001974 1977 1980 1983 1986 1989 1992 1995 1998 2001 2004 2007 2010 2013 2016 2019 FYTotal

Rivers

Lakes

Seas

Public waters water quality measurement results（2021）
Ministry of the Environment, Government of Japan

5

Domestic wastewater treatment systems in Japan
Johkasou
浄化槽
installedarea（既整備区域）

Rural community
集落排水
sewerage facilities, etc.
（未整備区域）
un-installed area

Sewage下水道systems
un-installedarea（未整備区域）

Ruralcommunity
集落排水
sewerage facilities, etc.
（既整備区域）
installed area

TT

Sewage systems

下水道（既整備区域）
installed area

Johkasou
浄化槽
un-installedarea（未整備区域）

 Sewage Systems : managed by the Ministry of Land, Infrastructure, Transport and Tourism
 Rural community sewerage facilities, etc.: managed by the Ministry of Agriculture, Forestry and Fisheries
 Johkasou: managed by the Ministry of the Environment

Trend of Johkasou’s spread status by city size
Population of
汚水処理人口普100(令和4年度末)

99.7%
95.8%

94.6%

80

88.5%

Sewage下:99.4%
99.4%

普

83.4%
Sewage89.4%
下:89.4%
Sewage下:86.5%86.5%

70

Penetration rate

92.9% (End
（万人 of FY2022)

93.1% 単独・汲み取り90

Sewage下:81.3%81.3%

60

Sewage54.3%

下:54.3%

及50Communityplant160.1%(0.1%)

40

Communityplant
0.3%3020(%)
10

農:0.9%

0

浄:5.8% 浄:7.2%

City
人口規模
Population

100万人以上
More than

1.0 Million

農:2.2%

浄:9.4%
Johkasou:9.4%

農:3.8%

浄:16.0%Johkasou16.0%

下水道
Sewage10,128systems
81.0%(81.0%)
コミプラ

汚水処理施設（全体）
Wastewater
treatment facilities

率

未普及人口without
Population
wastewater882
treatment(7.1%)
7.1%
普及人口 of
Population
11,624wastewater
treatment(92.9%)
92.9%

Sewage下:68.5%68.5%

wastewater treatment
全国平均：92.9

コ:0.3%
農:7.4%
Rural:7.4%

浄:21.4%
Johkasou
21.4%

50～100万人 30～50万人
10～30万人
5～10万人
5万人未満
than0.1 -0.3
0.5
– 1 0.3 -0.5
0.05 -0.1 Lesser
MillionMillion Million※東日本大震災の影響で調査不能な2市町村を除いた値。
Million 0.05 Million

農集排等
Rural community
302
seweragefacilities(2.4%) ,etc.
2.4%
浄化槽
Johkasou
1,178
9.4%(9.4%)■Sewage systems■Community plant■Rural community
sewerage facilities ,etc.
■Johkasou

Current situation of population served for treating domestic wastewater by different wastewater
treatment facilities
Type of treatment facility

Population served (x1,000 people)
End of FY2022End of FY2021

101,280 (81.0%)

101,181 (80.6%)

including Facilities for fishing villages, Facilities for forestry
villages, Simple wastewater facilities

3,018 (2.4%)

3,103 (2.4%)

Johkasou

11,784 (9.4%)

11,758 (9.4%)

Municipal Johkasou Installation Program

825

831

Johkasou Installation and Maintenance Program

6,229

6,203

Other Johkasou

4,730

4,725

160 (0.1%)

171 (0.1%)

Total population served

116,242

116,213

Percentage of population served

92.9%

92.6%

Total population

125,065

125,540

Total population not served

8,823

9,327

Un-installed rate

7.1%

7.4%

Sewage systems
Rural community sewerage facilities

Community plants, etc.

8General Information of Johkasou
 “Johkasou” is categorized as decentralized wastewater treatment system for domestic wastewater discharged
by household, building and so-on.“
 Johkasou have a combined purification structure capable of treating both night soil (black water) andmiscellaneous wastewater (gray water)
 Johkasou attains high and stable performance as same as that of sewage treatment plant and it has been
installed totally more than 3.9 million units in Japan.

Industrial wastewater, Domestic wastewater
Domesticwastewater

Sewage treatment, Decentralized treatment
Septic tank, wetland,DEWATS, etc., Johkasou

Clean,
purifiedwater

BOD removal, Nitrogen and/or Phosphorous removal
Johkasou
Usually installed undergroundTypical layout of small scale Johkasou setup for household

9Typical structure and treatment performance of Johkasou

Small and middle size
(5 ～ 51 P.E.)

Box shape

Large size
(51 P.E.～)

Cylindrical shape The performance criteria of Johkasou’s performance evaluation systemBOD≦ Standard type 20mg/L, Option 15, 10, 5mg/L
T-N (Total Nitrogen)≦ Standard type (NIL), Option 20, 15, 10, 5mg/L
T-P (Total Phosphorous)≦ Standard type (NIL), Option 2, 1, 0.5, 0.1mg/L
10Old and current type of Johkasou Domestic wastewater = Black water (Night soil) + Gray water(kitchen drainage, bath drainage etc.)

Current Johkasou in Japan

Current
JohkasouBoth Black water & Gray water are treated.

Publicwaterway

Old type Johkasou in Japan
Only Black water is treated and have lowtreating ability⇒ Heavy impact with 8 times pollutant load

In Japan, old type Johkasou is notconsidered as wastewater treatment
facility, and this is counted as untreatedwastewater.

Less
impact withlow
pollutantload

OldJohkasou

Heavy impact
with 8 times
pollutant loadWithouttreatment

Discharge of untreated wastewater11

Configuration of old and current type Johkasou

Number of Johkasou installed(person)

 Though new installation of old type Johkasou was prohibited in 2001, still approx. 3.6 million sets of oldtype Johkasou are used in Japan.
 The conversion to the current type of Johkasou is still a big issue in Japan.

Johkasou Act
enactedNational subsidy
program for Current
type Johkasou
established (forindividuals)

Total numbers ofJohkasou
installed :7,527,615

New installation of old type
Johkasou was prohibited
except in special cases

Old Type Johkasou
3,569,862(47.4% of total)

Old type
Current type

Current TypeJohkasou
3,957,753(52.6% of total)

▲
1985

▲
1990

▲
1995

▲
2000

▲
2005

▲
2010

▲
2015

▲
2020(year)

12Comparison of Sewage, Johkasou and Septic tank
Sewage（STP) *Category

Centralized

Capacity(m3/day)Large

Application

City covering with pipeline
networkJohkasouSeptic tankDecentralized

Small to middle

Small

For household, building, housing complex, community,hospital, school, public toilet, etc.

TargetBlack water & Gray waterBlack water

MethodAerobic (plus Anaerobic)

Anaerobic only

Treated water
quality- Good- BOD <20mg/L- Nitrogen & Phosphorous can be removed- Poor- BOD ≓ 100mg/L- Nitrogen and Phosphorous
can’t be removed

Discharge

Clean discharge is discarded directly to the river, lake,sea and so-on.

- Dirty discharge is penetrated
into ground- Gray water is discharged
without treatment

Main body

Civil structure constructed
at siteCivil structure constructed atsite

Maintenance works
Total period for
operation start

FRP manufactured infactory

Checking and adjustment, desludging, inspection,changing spare parts
Long for planning, financing,
construction*STP:
Sewage treatment plant

Desludging only
(every 3 to 5 years)
Short

13
Johkasou can be recognized as a “prefabricated small scale sewage treatment plant” in wastewater management

Application of Johkasou for domestic wastewater management and installation example overseas
 Application of Johkasou for domestic wastewater management(Ex. Poverty houses where frequent waterborn diseases are infected)f) Monumental Area

(Ex. For natural reserve, world heritage, etc.)

 Example of Johkasou installation overseas

Restaurant(China: 10m3/d)

Toilet in factory(Vietnam: 5m3/d)Canteen & toilet(Myanmar: 30m3/d)

Employee dormitory(Saudi Arabia: 530m3/d)

At the end of 2022, totally over 50,000 units of Johkasou are installed overseas

14Installation records of Japanese Johkasou Overseas
As of the end of December 2022 (Total) by Johkasou System AssociationUnited Kingdom ◇S 57units

India ◇S 123units, ◆M/L 379units

Pakistan ◇S 4units ◆M/L 1units◇S 2units

Vietnam ◇S 930units, ◆M/L 530units

Germany ◇S 370units
GreeceBangladesh ◇S 22units, ◆M/L 24units◇S 10units

Myanmar ◇S 756units, ◆M/L 274units

Hungary ◇S 3units

Thai ◆M/L 4units

Romania ◇S 209units
Italy

Taiwan ◇S 1unit, ◆M/L 1unit

Libya◆M/L 3units

Philippines ◇S 36units◆M/L 5units

Mali ◇S 1unit
Arab◇S 3units

South Africa ◇S 45units

Saudi Arabia ◇S 6units◆M/L 1unit

Mozambique ◇S 1unit

Palestine ◇S 1unit

Tanzania◆M/L 1unit

Syria◆M/L 1unit

Kenya◇S 157units◆M/L 12units

Iraq◆M/L 2unit

Mauritius◇S 1unit

Korea◆M/L 1unit

Panama ◆M/L 1unit

Total 51 countries

Grenada ◇S 1unit

Sri Lanka ◇S 370units◆M/L 174units

Nigeria ◇S 16units◇S 1unit

Small size 48,325units
M/L size 1,856units
Total 50,181units

Honduras ◇S 1unit
Costa Rica ◇S 2units

Laos ◇S 2units, ◆M/L 4units

Algeria◆M/L 8units

Egypt

Mexico ◇S 15units

China ◇S 30,314units, ◆M/L 18units◇S 11units 2022 recent (Total)

USA ◇S 6,551units, ◆M/L 19units

Oman ◇S 204units
Jordan ◇S 6units
Iran◇S 1unit

 Trend by years (Total)

Palau ◇S 17units, ◆M/L 3units
Malaysia ◇S 1unit
Singapore ◆M/L 4units

Papua
New Guinea◆M/L 1unit

Indonesia ◇S 200units,◆M/L 341units
Australia ◇S 7,832units, ◆M/L 39units
Kuwait◇S 2unit

Yellow colored : more than 100units◇S： Small-scale ( 5 PE ～ 50 PE)◆M/L ： Medium/Large-scale ( 51 PE ～ )Accumulated numbers

RussiaNepal ◇S 1unit, ◆M/L 4units

Around1.6times
in 3 years

15Thank you for your kind attention

Check Japan’s Johkasou System on Youtube ⏩
https://www.youtube.com/watch?v=r4xOKGbYWes