Analysts of material and energy flow in sewage treatment facilities in Japan

Energy consumption in sewage treatment facilities in Japan has increased du e to increasing tap water consumption To reduce the resource/energy consump tion in sewage treatment facilities. measures such as the selection of opti mum treatment processes and operating conditions should be considered. The objective of this study is to gather information necessary for the determin ation of optimum savage treatment processes and optimum operating condition s. The energy consumption and material now in sewage treatment facilities i n Japan are analyzed using statistical data. In 1994. reuse rate of treated sewage outside the treatment facilities in japan was 18% of the amount of domestic treated water. In this regard, reuse of water outside facilities s hould be encouraged. Average electric power consumption per unit volume of wastewater in sewage treatment facilities varies widely from facility to fa cility and closely correlates with the facility scale. For example, the sma ller the facility scale, the larger the electric power consumption. Treatme nt volume of savage in smaller facilities is much less than their capacity. 3.7 million t year(-1) of dehydration cake is incinerated and 0.1 million t year(-1) of it is converted by composting. The recycle ate of the cake wa s low. Developing a new sludge treatment process other than incineration is necessary.