DEA-Based Efficiency Analysis of Korean Public Wastewater Treatment Plants

This study used data envolpment analysis (DEA) to quantitatively compare the operational efficiencies of 256 public wastewater treatment plants in Korea, all of which employed A2O, SBR, or MBR processes. The input variables included unit electricity consumption per flow rate and consignment operation costs per flow rate, while the output variables were the removal rates of BOD, TOC, SS, TN, and TP. An input-oriented BCC-DEA model was applied to evaluate the relative efficiencies of the three processes. The analysis revealed that the A2O process achieved the highest average efficiency (0.873), followed by the MBR process (0.862) and SBR process (0.824) (F = 2.847, p = 0.032). The A2O process demonstrated high efficiency with low energy consumption (0.73 kWh/m³) and operational costs (0.39 thousand KRW/m³), reflecting optimization benefits from 30 years of accumulated operational experience. In contrast, the MBR process, despite producing excellent effluent quality, showed relatively low efficiency due to high input costs (1.83 kWh/m³ and 1.75 thousand KRW/m³). The SBR process exhibited superior TN removal performance (84.8%) but demonstrated lower overall efficiency due to substantial operational variability among facilities. These findings highlight the need to transition from traditional water-quality-centered evaluation systems to comprehensive performance assessments that incorporate energy efficiency. In addition, this study proposes differentiated policy directions tailored to the characteristics of each treatment process. The results provide substantial evidence to support the efficient operation of wastewater treatment facilities and guide policy development, particularly in improving the operation of existing SBR facilities and expanding the application of A2O processes.