Abstract: To scientifically and reasonably select rural sewage process, a model coupling life cycle sustainability assessment (LCSA) and multi-criteria decision analysis (MCDA) was constructed. Constructed wetland (CW), sequence batch reactor activated sludge process (SBR), anaerobic-anoxic-oxic process (A₂O), membrane bioreactor (MBR), and bio-contact oxidation (BCO) were chosen as the research objects to make assessment and propose improvement suggestions under the effluent quality standard reaching the first grade A standard of “Urban Sewage Treatment Plant Pollutant Discharge Standard”. The results showed that five systems contributed most of the environmental impacts (over 85%) and economic costs (over 60%) during the operation phase. CW had the best environmental and economic sustainability, which occupied a larger area. MBR had the worst environmental and economic sustainability, with better social sustainability. A₂O required more energy during operation resulting in poor environmental and economic sustainability, while SBR and BCO had the relatively balanced sustainability in the above-mentioned three aspects. The results of MCDA for different stakeholders showed that the MBR, SBR and BCO exhibited their advantages under different preferences, in which the CW had the best sustainability (0.59-0.70). However, CW was no longer the optimal scheme when the subjective weight of occupied land area reached 65%. Based on the evaluation results, users could improve sustainability of wastewater treatment processes and reduce the negative impacts of environmental, economic and social dimensions by optimizing the consumption during operation and flexibly adjusting the discharge standard according to the drainage direction.

Key words: rural sewage treatment, multi-criteria decision making, life cycle assessment, life cycle cost, life cycle sustainability assessment.