城镇污水处理排放标准改革的费效分析

Cost-effectiveness of discharge standard reform for household wastewater treatment

从费用效果角度对提高城镇污水处理排放标准的科学性和可实施性进行探讨,利用污染源普查数据,通过城镇污水治理投资和运行函数的构建,计算不同处理规模和排放标准下的污水处理投资和运行费用,在全国层面上计算提高污水处理排放标准所需费用和污染物的减排效果.研究表明:污水处理厂的投资和运行费用的增加随着污水处理规模的增加而递减.以污水处理厂正常运行率70%来计算,日处理能力在2.0×103～5.0×105t·d-1左右的污水处理厂,若将污水排放标准从二级标准升级为一级标准,增加的投资成本在623～323元·d-·1t-1,若不计设备的折旧费,增加的运行成本在0.20～0.11元·t-1之间;若按照减排的效果提升到一级B的排放标准估算,每增加一万元的投入,可新增污染物COD减排量1.21～2.25t,新增氨氮的减排量0.51～0.95t,新增总磷的减排量60.3～112.3kg.

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.