Supply Efficiency Evaluation for Wastewater Treatment Facilities in Towns of Western China: A DEA-Malmquist Approach

Wastewater governance is a core component of achieving the United Nations Sustainable Development Goal 6, and the supply imbalance of urban and rural wastewater treatment facilities is a common challenge in the urban-rural transformation of developing economies. As key nodes of urban-rural integration, towns in Western China have prominent shortcomings in the supply efficiency of wastewater treatment facilities, yet existing studies lack systematic quantitative assessments targeting this region. Based on panel data of wastewater treatment facilities in towns across 11 provinces in Western China from 2015 to 2022, this paper adopts the DEA-Malmquist Index to conduct static efficiency measurement, decomposition of dynamic Total Factor Productivity Change (Tfpch), and regional heterogeneity analysis. The findings show that the overall static supply efficiency of wastewater treatment facilities in towns of Western China is below the medium level. During the study period, the arithmetic mean of Comprehensive Efficiency was only 0.595, and the dual deficiency of Pure Technical Efficiency and Scale Efficiency restricted the improvement of performance; Tfpch achieved an average annual growth rate of 22.7%, which was entirely driven by Technological Change. By contrast, Technical Efficiency Change experienced an average annual decline of 7.2%, with the continuous decline of Pure Technical Efficiency Change being the core bottleneck; there is significant inter-provincial heterogeneity in supply efficiency, with the overall performance of southwestern provinces outperforming that of northwestern provinces. This study can provide empirical evidence for the optimization of environmental infrastructure in Western China, as well as a reference for environmental governance in similar regions worldwide.