Saitama is a neighboring city of Tokyo. With a population of 1,230,000 and a relatively high population density, the city combines off site and onsite sanitation systems. Around 90% of its population is connected to the sewerage system while the rest rely on johkasousystems.
A johkasou (also known as Packaged Aerated Wastewater Treatment Plant or PAWTP) is a compact onsite wastewater treatment facility. It is highly efficient for individual households or small communities located mostly in rural or peri-urban areas where there is no access to a sewerage system. It can treat both black water (wastewater from toilets) and grey water (non-fecal wastewater from kitchen sinks, bathroom, etc.) to achieve a high effluent quality of less than 20 milligrams per liter (mg/l) biochemical oxygen demand (BOD).
Manager, International Affairs
Japan Sanitation Consortium
Intelligent Building, Yushima Iyasaka 5F
Yushima 3-26-9, Bunkyo-ku
Tokyo 113-0034, Japan