Study On Differentiation Cost Accounting Technology Of Municipal Sludge Treatment And Disposal Based On Life Cycle Cost Model

Municipal sewage treatment produced a large amount of sludge,which is harmful without proper treatment and disposal.A wide range of technological routes were used for sludge treatment and disposal,and the cost varies widely across different technological routes.There are three problems in cost assessment of sludge treatment and disposal,First,cost accounting cannot cover the whole process chain of sludge treatment and disposal.Second,environmental costs caused by carbon emissions is not included in the cost accounting.Third,the results of existing cost accounting are not uniform in time.The objective of this paper was to construct a model of differential cost accounting for sludge treatment and disposal based on life-cycle-cost.The model considers economic cost of treatment,transportation,and disposal,and it involves the cost of environmental pollution caused by sludge treatment and disposal.The environmental cost was calculated used the parameters of cost accounting for unit carbon emission control.The economic cost of sludge treatment and disposal is obtained via questionnaire survey and literature research.Finally,the economic costs of each unit of sludge treatment and disposal in different years are corrected and evaluated based on the benchmark discount rate and the consumer price index.The differential cost accounting of seven typical sludge treatment and disposal technical routes are carried out by the model.The results show that the life cycle cost of sludge gravity concentration+plate frame dehydration+heat drying+separate incineration(R2)is highest(12725 yuan/DT),life cycle cost of gravity concentration+centrifugal dehydration+thermal hydrolysis+anaerobic digestion+plate frame dehydration+land use(R7)is in the medium level,sludge gravity concentration+centrifugal dewatering+mixed incineration(R3)has the lowest life cycle cost.The environmental cost of sludge gravity concentration+plate frame dehydration+sanitary landfill(R1)technical route is highest(219.13 yuan/DT),and the environmental cost of the R7 route is lowest(-66.15 yuan/DT).Taking Beijing as an example,in order to encourage the promotion of the R7 technical route to treat sludge,a subsidy of 210 yuan/t(80%moisture content)is required.The differentiated cost accounting model and related cost data of sludge treatment and disposal constructed in this study can provide theoretical support for the selecting technologic routes of sludge treatment and disposal.