Advanced domestic wastewater treatment tanks (Johkasou)

Needs Address

The need to reduce the impacts of deteriorating quality of public waters (particularly enclosed water bodies, etc.) as a result of climate change, in areas that may face declining sanitation conditions. Particularly applicable in response to the need to mitigate impacts in regions where water pollution is occurring due to urban population growth associated with economic growth, or due to rapid industrial development.

Adaptation effects

• Limiting the deterioration of water quality in enclosed water bodies due to the effects of climate change, etc.
• Prevention of deterioration of sanitation conditions and reduction of disease risk due to climate change, etc.
• Improved wastewater treatment capacity to handle extreme events

Overview and Features

• Involves installation of small joint johkasou in single-family dwellings with the aim of improving the surface water environment.
• Can consider using recycled water from large membrane-separation-type johkasou at commercial facilities where sewage-treatment costs are high. 

Example of johkasou to be installed

Source: Model project for improvement of the Asian water environment, 2012 Project (Project for improvement of the wastewater quality in central wide area of Jakarta city, Indonesia by Johkasou) (in Japanese only).

Cost

Initial costs: For large johkasou (200 m³/day): 10 million yen per unit (equipment 7 million yen, installation 3 million yen)

Energy source

Electricity

Ease of maintenance

Regular maintenance is required for the johkasou to function optimally. 

The main maintenance tasks are as follows:

• Sanitization
• Adjust aeration in carrier flow tank, adjust circulation volume, clear aeration tubes, adjust overflow weir, adjust amount of chemical additive dissolution. 
• Troubleshooting of odor, foaming, low/high adhesion, obstructions, etc. 
• Individual inspections and repairs/maintenance each piece of equipment
• Cleaning
• Routine replacement of parts

Technology performance

Large johkasou systems can process between 1 and 1,000 m³ daily. Effluent has a BOD of 20 mg/L. 

Comparison of wastewater treatment equipment

Source: Model project for improvement of the Asian water environment, 2012 Project (Project for improvement of the wastewater quality in central wide area of Jakarta city, Indonesia by Johkasou) (in Japanese only).

Considerations

For johkasou, factors affecting the installation potential and post-installation effectiveness include national and regional legislation/regulations relating to water quality, economic support/incentive programs, and institutional capacity for proper maintenance, etc.

For example, the following issues affect efforts to improve the water environment in Indonesia:

• Weak environmental protection standards relating to wastewater BOD water quality.
• Inadequate systems of inspections and administrative guidance relating to water quality and wastewater
• No certification or installation subsidy/incentive programs for wastewater treatment equipment
• The area classification of onsite versus offsite treatment is not formulated in regional cities.
• No mechanisms are in place for routine maintenance and sludge removal.

Co-benefit, suitability for developing countries

• Improvement of sanitation by proper treatment of domestic wastewater, etc. 
• Creation of employment for installation, operation and maintenance of the systems. 

Information Resources

• Japan Education Center of Environmental Sanitation
  http://www.jeces.or.jp/en/technology/index.html
• Johkasou System Association (JP only)
  http://www.jsa02.or.jp/01jyokaso/index.html
• Model project for improvement of the Asian water environment, 2012, Environment Management Bureau, Japan Ministry of the Environment
  http://www.env.go.jp/water/coop/asia_business/weib.html
• Final Report, FY2011 Asia Water Environment Improvement Model Project (Water Quality Improvement from Indonesia Jakarta Special District Johkasoh demonstration facility) (in Japanese only).