China’s wastewater treatment plants (WWTPs) have consumed a large amount of electricity, which is threatening the sustainable development of regions with severe energy scarcity. In this paper, we developed a novel framework for evaluating the technical efficiency of WWTPs and identifying the key pathways to save electricity and improve treatment efficiency. First, multiple regional initial and integral electricity scarcity risks were investigated based on the proposed electricity stress index (ESI). Then, an index system covering two inputs (scale and electricity consumption) and six outputs (COD, BOD, SS, NH3-N, TN and TP pollutant removal volumes) was constructed to assess the technical efficiencies of 3776 WWTPs by introducing the multiple electricity scarcity risks into data envelopment analysis (DEA). The results showed that the original average technical efficiency score of investigated samples was 0.340, of which only 28 samples were relatively effective. The remaining WWTPs had different levels of input excesses and over 60% electricity overcapacity, indicating that the substantial potential for technical efficiency improvement and electricity saving. Moreover, regional electricity scarcity risks differed significantly and the technical efficiency changed significantly considering ESI. This paper may present a useful tool for the technical efficiency assessment of WWTPs.
Keywords electricity efficiency, wastewater treatment, electricity stress index, data envelopment analysis, multi-regional input-output analysis