Abstract
The expansion and concentration of urban areas cause the urban environment degradation, e.g. revealed as heat island phenomena. Many researchers have reported on the anthropogenic heat impact to the atmosphere, while not so many researchers have reported on the impact to the hydrosphere. To obtain the water and heat balance in artificial sewage system, we carried out the sewage temperature observation in wastewater treatment plants. By analyzing the observed data and other statistical data from Tokyo metropolitan, we got the following major results. 1. The leaching water from soil into sewage pipe dominates 22% of the whole sewage. 2. The heat added by water use in the urban area during one year amounts to 9% of whole energy use. 3. The process of heat flow in the sewage system is revealed in each season. In summer, the sewage loses its heat by conduction from the sewage out of the pipe and gains heat at WWTP. Totally, the sewage system reduces sewage heat and discharges it to hydrosphere. 4. In winter, both the conducted heat and the heat added in WWTP are small. Thus the sewage system doesn't change the heat.
