Water reuse and recycling in Japan — History, current situation, and future perspectives

Abstract

Water reuse is an effective option all over the world for saving water resources, reducing environmental impacts, and reducing the costs and energy involved in water resource management. In Japan, non-potable water reuse has been implemented in several cities since the 1980s, mainly for urban applications such as toilet flushing, urban stream water augmentation, and landscape irrigation. However, utilization of reclaimed water is still limited in Japan due to the inadequate quality standards for reclaimed water and the high energy consumption of water reclamation facilities. From 2010 to 2015, a Core Research for Evolutional Science and Technology (CREST) project was carried out in Japan to develop energy-efficient water reclamation processes utilizing membrane technologies and ozonation processes. A comprehensive evaluation of the process performances and the economic feasibility showed that the UF ​+ ​UV (ultrafiltration ​+ ​ultraviolet radiation) process provided removal of viruses to a level adequate for water reuse for agricultural purposes at low cost. Based on the results from the CREST project, a demonstration plant incorporating the UF ​+ ​UV process was constructed at the Itoman wastewater treatment plant in Okinawa to evaluate performance in terms of virus removal and to implement agricultural water reuse. Other innovative technologies are also under development in Japan to reduce the cost and energy involved in water reclamation. This paper introduces the history, current situation, and future perspectives of water reclamation and reuse in Japan.