Comprehensive evaluation of performance of wastewater treatment plants in Kunming

The performance of seven wastewater treatments with four different treatment processes types (oxidation ditch, ICEASE, 3AMBR and A²O) in Kunming was evaluated with indicators including technical performance, economic cost, and environmental impact (global warming and eutrophication). The results showed that all wastewater treatment plants had good performance in the removal of BOD, SS, and NH₄⁺-N with the removal percentage above 91%, the removal percentage of COD was over 86%, the removal percentage of TP was in the range of 86%~96%, and the removal percentage of TN was in the range of 56%~76%.Economic costs were mainly contributed from energy consumption and were closely related to the treatment process and water quality of both influent and effluent; the operation cost of 3AMBR was much higher than that of other treatment processes. Greenhouse gases emission was mainly from energy consumption and nitrous oxide emission from the effluent, and 3AMBR had the highest greenhouse gases emission among all treatment processes. The eutrophication effect of the effluent was mainly contributed by nitrate and was highly affected by treatment processes. Combined with the pollutant removal performance and comprehensive cost, ICEAS had the best comprehensive performance while 3AMBR had the relatively worse comprehensive performance.