Outline and Problem of Reclaimed Water Supply Business in Tokyo

Tokyo Bureau of Sewerage (TBS) of Tokyo Metropolitan Government (TMG) is proceeding to the advanced treatment and recycling the treated wastewater for various uses in urban areas.Results of the amount of the reclaimed water supply in 2007 were 30,635,400m3/year. This corresponds to 1.9% of the amount of the authorities total discharged water. In the main usage, flush toilet water was 3,261,900m3/year, and discharge for a river basin environmental recovery to the river where the flow of the river had decreased was 27,329,400m3/year. Besides this, it is used to the road watering for mitigation of the heat island phenomenon, and sprinkling the plant, etc.This business has the problem concerning the supply volume of water, the water quality, crisis control.The problem of the supply volume of water is shortage of make water ability at the peak of use. We cope with this problem by a fine operation management and by the reinforcing ability of make water.The problem of the water quality is a disappearance of the residual chlorine, the incorporation of the chironomidae larvae, and the establishment of the risk management technique to a pathogenic chlorine resistant microorganism. The countermeasure concerning chlorine is to improve the nitrification efficiency on the sewage treatment process. Pathogenic microorganisms and chironomid countermeasures is the installation of equipments that can remove them and of the disinfections by ozone and ultraviolet rays.Deterioration of piping and partition valve and the risk management at the earthquake are problem on the facilities side, it is necessary to settle on short-term and a long-term facilities planning, and to execute it steadily.