Technology for Advanced Treatment of Rural Sewerage in Japan
It is important to develop techniques for advanced wastewater treatment in rural communities, based on an extension of biological treatment methods. The target for treated water quality is less than 10 mg/l for BOD, COD, SS, T-N and less than 1 mg/l for T-P. In this paper, the application of (1) contact aeration process with treated water returning system, (2) batch-activated sludge process, (3) oxidation ditch process, was introduced, after reviewing the principles of biological denitrification, biological dephosphorization and phosphorus removal using a submerged iron contactor. Operation control for the above processes and new developments in technology such as immobilization methods and membrane separation method were also described. The studies conducted so far have enabled to develop denitrification methods, while phosphorus removal methods require further investigations.