A Performance Evaluation System for PPP Sewage Treatment Plants at the Operation-maintenance Stage

Sewage treatment plants are essential in improving the quality of receiving water bodies, contributing to healthy and sustainable urban development. The increasingly common public-private partnership (PPP) model of sewage treatment facilities may not yield the expected benefits, often compromised by inadequacies in the complex operation-maintenance stage. Holistic criteria and methods to define and judge a plant’s performance are lacking. To fill the knowledge gap, this study established a performance evaluation system applicable to the critical operation-maintenance stage of China’s PPP sewage-treatment industry. First, the range of quantitative and qualitative indicators was surveyed by literature review, and an appropriate subset was selected according to expert judgment. Second, the multilevel extension principle of matter-element analysis was combined with the analytic hierarchy process to determine the performance level and establish a comprehensive, efficient and practical evaluation system. The proposed method was tested on two PPP plants to confirm its applicability and reliability in assessing operation-maintenance functions. The study identified the diagnostic criteria to refine the design, operation and maintenance parameters to optimize plant performance. The findings provided an assured and comprehensive quality control scheme and a practical tool for governments and other parties to assess the service delivery quality of PPP plants.