Efficiency evaluation of urban wastewater treatment: Evidence from 113 cities in the Yangtze River Economic Belt of China.

To resolve the increasing water pollution crisis, scientifically evaluating the urban wastewater treatment efficiency (UWTE) is an essential prerequisite to ensure the success of any policies aiming to decrease water pollution. Using 113 city-level panel data in the Yangtze River Economic Belt (YREB)-the biggest economic belt in China, during 2008-2017, this study aims to evaluate the UWTE based on a Bootstrap-DEA and to measure the efficiency changes through a Malmquist index model. The results show that the overall UWTE is at a low level, evidenced by the fact the average efficiency score is 0.51 during 2008-2017, and no cities have an efficiency score equal to 1. The UWTE is in the trend of decreasing, which is mainly caused by the decline of technical progress change. 69.02% of cities are in the state of decreasing returns to scale. The UWTE shows considerable disparities both between regions and city sizes, with the highest efficiency score observed in the midstream area and large-sized cities, the lowest efficiency score observed in the downstream area and small-sized cities. The findings of this study are expected to have great practical significance for governing wastewater pollution.