Abstract
Towards the realization of "resource recovery type sewage treatment plant" as a water, materials and energy circulation base in the watershed, this study is conducted on the core sewage treatment plant (STP) of K city which is one of the largest scales in Japan. There were investigated digestion gas power generations as energy recovery, phosphorus recovery as resource recovery, advanced treatment as water use, and calculated the potential (recoverability). In energy recovery, the amount of generated electricity will increase to 51,760 kWh/day when receiving sludge from three STPs and solubilizing excess sludge, and the self-sufficiency rate will be expected to be 28.8 %.In the case of phosphorus recovery, when receiving sludge from three STPs and solubilizing excess sludge, the amount recovered from the dehydrated filtrate will be about 800 kg /day, and overall the phosphorus recovery rate will be 50 %. In the case of advanced treatment, the quality of the discharged water is improved in the entire STP. Not only the water quality but also the electric power consumption unit tends to decrease. When evaluating water, materials and energy recovery function as the environmental performance of the STP as an indicator of water eco-efficiency, 4 kg/kWh will be expected by achieving resource recovery type STP with digestion gas generation, phosphorus recovery and advanced treatment, from current situation 2.68 kg/kWh.
