Onsite Source-Separation and Synergistic Treatment of Household Wastewater: Mechanism Elaboration, Technology Optimization, and Advantage Analysis

Onsite treatment of wastewater is a suitable sanitary drainage strategy for decentralized residences. With the techno-logical developments in process and management, the conventional onsite treatment system has reached a cost-performance ceiling, and breaking through this ceiling is a new challenge. Based on the advantages of onsite systems in the respective collection of toilet wastewater and washing wastewater, an onsite source-separation and synergistic treatment (O3ST) system was introduced in this research after the features of these two kinds of wastewater were elucidated. After a 363-day operation, the mechanism of N-pollutant removal by partial nitritation and denitritation of the O3ST system was elaborated, and the removal performance of this system was tentatively optimized by applying the strategies of reflux setting and alkalinity regulation. Subsequently, an advantage analysis of the O3ST system was conducted. The application of this system improved upon the stability and resilience of onsite systems due to the achievements in the load separation of wastewater quality and quantity. Moreover, the TN removal rate reached 25.2 g/day/m(3), and the sludge observed yield was as low as 0.087 gVSS/gCOD. The technical feasibility and superior cost-performance of the O3ST system were verified, providing support for system optimization and engineering.