Sewage Treatment Plant as a Circulation Base of Water, Materials and Energy in Watersheds

摘要

Based on the concept that sewage treatment plants should serve as the circulation bases of water, materials and energy in watersheds, to calculate energy recovery, power generation can be done using digestion gas. To calculate material recovery, efficiency was set for MAP process, HAP process and Ash alkaline process for phosphorous recovery. To examine water reuse, this study deals with treated water for irrigation. Using a model treatment plant with a capacity of 48,000m3/day, the use of water eco-efficiency (=Water environmental load removed / Power consumption) was proposed for the comprehensive evaluations. Power consumption decreased by using digestion gas generation, and water eco-efficiency increased to 1.73 kg/kWh from 1.62 kg/kWh in the benchmark. The water environmental load removed increased in the phosphorus recovery, and water eco-efficiency rose to 2.49 kg/kWh in the Ash alkaline process. In the case of water reuse, water eco-efficiency rose to 2.40 kg/kWh for irrigation. In addition to energy recovery, efficient materials recovery and water reuse are important considerations in creating a circulation base.