Hiroshi OgawaJapan Education Center of Environmental Sanitation2-23-3 Kikukawa, Sumida-ku, Tokyo 130-0024, Japan

Domestic Wastewater Treatment

by Johkasou Systems in Japan

① Blower② Air pipe③ Inflow pipe④Wastewater pit⑤ Johkasou

(building frame)⑥ Disinfection chamber⑦ Outflow pipe (effluent)

An Example of Johkasou Installed at Individual House

What is Johkasou?

Anaerobicfilter tank

Contact aeration tank

Sedimentationtank

Disinfectiontank Effluent

Separated sludge Sludge

Influent

Effluent water qualityBOD ≦20 mg/l

A small-scale Johkasou (FRP)

Inflow pipe

Outflow pipe

Flow equalizationtank

Contact aeration tank (1st room)

Contact aeration tank (2nd room)

Sludge thickening-storage tank

Outflow pump tank

Sedimentation tank

Disinfection tank

Middle-scale johkasou

A Middle-scale Johkasou (FRP)

A Middle-scale Johkasou (RC)

Main Systems for Domestic Wastewater Treatment

Johkasou Rural Sewerage

Public Sewerage

Domesticwastewater

Stormwastewater

Night soil

Night soil + Gray water3

Night soil treatment facility1

Tandoku-shorijohkasou2

(Storage tank)

Sewerage system

Johkasou4

Rural sewerage system

Community plant

(Urban storm drainage system)

Separate sewer system Combined sewer system

Note: 1. Night soil treatment facilities also treat sludge collected from tandoku-shori johkasous,community plants, gappei-shori johkasous and sewerage system in rural area.

2. The many are installed in individual houses. 3. Gray water is miscellaneous domestic wastewater except night soil.4. Though not many facilities are installed in individual houses, the number is increasing.

Various Systems for Treatment of Night Soil, Sewage and Wastewater in Japan

Publicwaterbodies

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1965 1970 1975 1980 1985 1990 1995 2000 2005 2010

Fiscal Year

Population, milion

Total population

Population of flush toilets use

Population of johkasou use

Population served by sewerage system

Trends of Populations Served by Johkasou, etc.

Sludge from johkasous can be used as fertilizer or for biomass production.

Johkasous have high resistance against earthquake and other disasters.

Treated water can easily be reused for various purposes as a reliablewater resource.

Wastewater collection and johkasou installation receive less influence of topographic conditions at the site.

A small-scale johkasou can be installed at a low cost and in short time.

Conserving water in small rivers, a human-closely water environment will be formed.

Miscellaneous domestic wastewater can be treated, contributing to prevention of water pollution.

Flush toilets can be used in unsewered districts.

Advantages of Johkasou System

BOD Loading per capita per dayof Domestic Wastewater from Household

Night soil

BOD loading43g/cap･ｄ

Cooking Cleaning etc. Washing/Bathing

Gray water

Cooking

Cleaning

Bathing

Wastewater amount (200L/cap･day)

Flush toilet 40L 72L 38L50L

Administrative AgenciesRelated PersonnelJohkasou ManagerAdministrative Agencies

GovernorOr Mayor

Document inspection for installation

Specifiedadministrativeagency

Minister of the Environment orGovernor

Submission Recommendation

Order of modificationOr rejection Construction

Manufacturer Minister of Land,Infrastructure and

Transport

Application

Approval of type and model

Construction company

Governor Application

Registration Minister of Land,Infrastructure and

Transport Johkasouinstallation worker

Qualification

Legal examination after installation

Specifiedinspectionagency

DesignationMinister of Land,Infrastructure and

Transport Minister of the Environment

Agency for the examination

Agency for the training courses

Designation

Designation

Operation and maintenance

Johkasou operator Minister of the Environment

Qualification

Governoror Mayor

Maintenance vendor

Application

Registration

Desludging Desludging vendor

Municipal Mayor

Application

ApprovalSpecifiedinspectionagency

Annual legal examination

Legal Systems of Johkasou Systems（Johkasou Law）

Johkasou Technicians and Vendors on Johkasou Business

65Specified examination agency

38

4,806

9,087

14,205

2,533

77,728

63,104Number of person/vendor

Vendor for johkasou desludging

Johkasou desludging technician

Vendor for johkasou O&M

Johkasou manufacturer

Johkasou inspector

Johkasou installation worker

Johkasou operatorClassification

(By the end of Mar. 2005)

Reuse of Effluent and Sludge

Johkasou

Domestic

Wastewater

Effluent Storage Tank

Effluent can be used for:*Flushing toilet

*Watering

*Car washing

*Firefighting

Sludge can be for Compost

Sludge

Effluent

Comparison of Different Subsidy Programs

Amount borne by the house owner(￥520,000)

Amount subsidized by municipalities and the

government(￥340,000)

Amount borne by the house

owner(￥90,000)

Sewerage works Amount subsidized construction bond by government funding(￥480,000) (￥290,000)

(For installing a johkasou of 5 NUD, which will cost ¥860,000 if it is not subsidized)

In the case of Johkasou Installation Promotion Program:

In the case of Johkasou Installation Program in Specified Areas:

Toward the Water Quality ProtectionToward the Water Quality Protectionin Public Water Bodies and the Creationin Public Water Bodies and the Creationof Desirable Water of Desirable Water , Reuse of Effluent and , Reuse of Effluent and Sludge Sludge

The EndThe End