エネルギー・アナリシスによる水循環システムの評価

Abstract

This paper appraised 4 models of water recycle systems in urban area such as wastewater reuse system and rain water usage from the point of view of energy consumption.Input-output analysis was used for the calculation of energy consumption. Not only the direct energy such as electric power and fuel but also the indirect energy used for production of equipments or parts in the water system were taken into consideration.The main results obtained were as follows.(1) The least energy consumption model was unrecycle model.(2) The largest energy consumption model was individual recycle model, but in low-densed areas below 90-150 households/km2 it was advantageous than unrecycle model.(3) The energy consumption of wastewater reuse system was mainly attributed to the distribution system and was about 15% more than that of water works.(4) Recharge of groundwater by infiltration of rain water was better than on-site rain water usage because FRP water tanks consumed a large amount of energy.(5) Works such as water treatment or water distribution consumed about 50% of the maintenance energy in unrecycle model and the rest was considered to be consumed in the business in the works.(6) From the aspects of the energy consumption, johkaso (on-site domestic wastewater treatment system) was advantageous than sewage works in areas below 196 households/km2.