Evaluation of resource-based rural sewage treatment system driven by clean energy in Northwest China

Rural areas in Northwest China are sparsely populated. Traditional centralized domestic sewage treatment facilities have large-scale investments, high operating costs, and complicated operation and maintenance management, challenging their application in these areas. Given the abundant clean energy and limited agricultural irrigation water in Northwest China, this study constructs a solar-wind driven rural domestic sewage treatment system with a treatment scale of 1.5 m3/d and HRT of 14 h. Effluent quality was suitable for farmland irrigation. The efficiency of complementary solar-wind power generation and the system operating performance and potential application value were assessed. The effluent CODCr meets the Class A vegetable irrigation standards (average removal rate is 70 %) in the "Standard for Irrigation Water Quality" (GB5084-2021). The average retention efficiencies of NH4+-N and SRP are 100.23 % and 104.3 %, respectively. Using the emission factor method, indirect and direct carbon emissions and the carbon reduction potential were evaluated. The carbon reduction rate during the life cycle is 53.15 %. Finally, a life-cycle cost evaluation model quantified a 25-year life cycle cost-effectiveness. The application potential was confirmed based on investment costs. This study demonstrates this novel treatment system feasibility in terms of operational performance, carbon emissions, and costeffectiveness and provides a scientific basis for low-carbon and sustainable resource recycling to rural sewage treatment systems.