The Investment Efficiency Of Urban Sewage Treatment Considering Environmental Benefits

Under the current situation of increasing water shortage in China,sewage treatment plays a decisive role in relieving water stress and improving urban living environment,and is an effective way to achieve urban ecological environment improvement and water conservation.At the same time,sewage treatment is also a public service industry,which not only has public welfare,but also has certain economic value.The public welfare is mainly reflected in the improvement of the ecological environment through sewage purification,the reduction of urban water pollution,and provision a more comfortable living environment for residents.It has environmental benefits that cannot be ignored.Economic value is mainly reflected in the role of government,reclaimed water.Reuse the value brought by market supply and demand.However,the domestic evaluation system for urban sewage treatment investment efficiency is not comprehensive.Most scholars only consider the technical efficiency and cost input for the operation efficiency of the sewage treatment plant,and do not consider the environmental external influence of the sewage treatment project,so that they are ignored.In this paper,the directional distance function model is used to determine the shadow price of sludge(SS),chemical oxygen demand(COD),total nitrogen(TN)and total phosphorus(TP)in wastewater to quantify the environmental benefits of wastewater treatment.Thereby the external cost is monetized and incorporated into the sewage treatment investment evaluation system.The results show that the average shadow prices of the four pollutants of SS,COD,TN and TP are-0.012 million / t,-0.287 million / t,-0.685 million / t,-68.88 million / t,and the east regional pollutant emission reduction effect is significantly higher than that of the central and western regions;When the environmental benefits are not considered,the average urban sewage treatment investment efficiency is 0.352,and the average efficiency after considering environmental benefits is 0.829,which indicates urban sewage treatment contributes to environmental improvement is far greater than its economic value.The comprehensive efficiency values of the provinces are uneven,and the eastern,central and western regions are quite different.Most of the frontiers of the efficiency value are the eastern coastal cities,and some of them have redundant investment;the central and western regions have more infrastructure than the eastern regions.Behind the urban sewage treatment rate is insufficient,it is necessary to increase the investment construction and upgrading of sewage treatment facilities to improve the sewage treatment capacity and effluent quality.