Cost-effectiveness of discharge standard reform for household wastewater treatment
城镇污水处理排放标准改革的费效分析

Using national pollution census data, we analyzed the scientific merit and feasibility of increasing discharge standards for municipal wastewater treatment plants. By constructing two functions, investment and operating costs, we calculated the total national costs of municipal wastewater treatment and associated reduction in pollution discharge under different wastewater intake and discharge standards. The marginal investment and operating costs decreased with increasing wastewater intake. The plant under study was assumed to have a daily handling capacity of between 2,000 and 500,000 tons and to operate at 70% of its full capacity. An additional investment of RMB 623~323 yuan and an additional operating cost of RMB 0.2~0.11 yuan (not taking into account the depreciation of the equipment) is required to treat each ton of wastewater if the discharge standard is changed from Grade 2 to Grade 1. Moreover, to meet the Grade 1B discharge standards, every RMB 10,000 yuan investment would result in a reduction in the discharge of COD by 1.21~2.25 ton, ammonia nitrogen by 0.51~0.95 ton, and total phosphorus by 60.3~112.3 kg.