Analytic hierarchy process method for rural domestic sewage treatment processes − a case study of Baiyangdian in China

Comprehensive evaluation of rural sewage treatment technologies is crucial for optimizing resource utilization, mitigating environmental impacts, and guiding sustainable development strategies in the context of rural infrastructure challenges. However, the comprehensive evaluation of rural domestic sewage faces several challenges (e.g., lacking of cost-benefit analysis, limited public participation, and insufficient assessment of social impacts). In this research, an analytic hierarchy process integrated with life cycle assessment (LCA) is proposed to comprehensively evaluate the environmental, economic, technological, and societal impaction of typical rural domestic sewage treatment technologies. Anaerobic-anoxic–oxic + membrane bio-reactor (A²O-MBR, M1), modified A²O-MBR (M2), pre-denitrification-anaerobic-anoxic–oxic + moving bed biofilm reactor (A³O-MBBR, M3) and modified A³O-MBBR (M4) are selected as typical treatment technologies. Under LCA, M4 shows the smallest environmental impact (1.73E-10), indicating that increasing the sludge reflux rate and the nitrification reflux ratio can effectively mitigate environmental harm, minimize impact, save energy and reduce consumption. Taking all factors into consideration, the indicators (i.e., global warming potential (1.35 %), total cost of sewage treatment (3.19 %), nitrogen removal efficiency (2.09 %), and localized infrastructure (1.56 %)) significantly influence the comprehensive evaluation. The multi-objective comprehensive assessment demonstrated that M4 (6.88) is the optimal process, followed by M1 (3.73), M3 (5.74) and M2 (5.95). This research provides a reference for the government and enterprises to reform the rural domestic sewage treatment technology from a multi-objective perspective.