Analysis On The Comprehensive Environmental Benefit Of The Upgrading Of Urban Sewage Treatment Plant

Facing the increasingly serious problem of water pollution,sewage treatment plant,as an efficient end treatment means in the whole sewage treatment project,has been widely used now.In recent years,with the new national standards,new requirements put forward,the national sewage treatment plants will face the work of upgrading.The upgrading of sewage treatment project not only reduces pollutants,but also consumes a lot of resources and energy.What is the environmental benefit of this process?Therefore,this paper uses life cycle assessment(LCA)method to evaluate the necessity and feasibility of the upgrading of sewage treatment plant by calculating and analyzing the comprehensive environmental benefits before and after the upgrading.First of all,through the analysis of the theory of life cycle assessment,combined with the characteristics of the upgrading project of sewage treatment plant and the previous research results,the purpose and scope of the study are defined,and the life cycle is limited to the operation stage.Taking 1 × 104m3 treatment capacity as the basic function unit(FU),the input and output data of the sewage treatment plant during the operation period before and after the upgrading are compiled into the analysis list.Then,according to the different environmental impact substances,the environmental impact is classified,and the different environmental imdpact is chaacize according to the characteristic model published by EPA.Then,nine scale method and analytic hierarchy process are used to calculate the weight values of different impact types,and the characteristic results are quantified.Finally,the comprehensive environmental impact values of the case sewage treatment plant before and after the upgrading are obtained,and the life cycle interpretation is carried out,and the corresponding suggestions are put forward.The mais conclusions are as follows:(1)According to the analysis of environmental impact assessment,the impacts of WWTP operation on environmental classification are:climate change impact potential;fossil fuel consumption;landfill space consumption potential;water resource consumption;black and smelly water impact potential;atmospheric haze impact potential;water eutrophication impact potential;environmental acidification impact potential;photochemical smog impact potential;human Physical health affects potential.(2)In the case of sewage treatment plant,when the first level a discharge standard(GB18918-2002)is implemented before the upgrading,the impact load on the environment is 1220.54/FU;when the class a standard of Tianjin(DB12/599-2015)is implemented after the upgrading,the impact load on the environment is 1689.97/FU,with an increase of 469.43/FU compared with that before the upgrading,and the two most significant impact types are fossil fuel consumption(131.74/FU)and climate change impact potential(308.34/FU),accounting for 93.75%of the increase in environmental impact load(469.43/FU)after the upgrading,of which coal,CO2 and NOx are the main impact factors,mainly from the power consumption of new advanced treatment process equipment and the environmental release brought by road transportation and crude oil production.(3)Comprehensive analysis on the benefit of pollutant reduction in sewage treatment,in the operation stage before and after the upgrading of the sewage treatment plant,the positive benefit of pollutant reduction to the environment is-1091.46/FU and-1131.18/FU respectively,and the negative benefit of resource and energy consumption is 1220.54/FU and 1689.97/FU,that is to say,the sewage treatment plant after the upgrading of the standard brings the positive benefit of 39.72/FU to the environment,while the positive benefit increases by 469.43/FU.Therefore,it is unreasonable for the case sewage treatment plant to upgrade to 'quasi class ? water'.(4)In order to improve the comprehensive environmental benefits of the sewage treatment plant,the following suggestions are put forward:?upgrading,Tianjin(DB 12/599-2015)class A and quasi class IV water quality discharge standards need to discuss;?according to the local conditions,according to the water quality and environmental capacity of the receiving water body,reasonably determine the urban sewage discharge standards;?improve the quality and efficiency,and form a complete pollution control system project from source collection,process transportation,end treatment and recycling;?turn waste into treasure to realize the reduction,stabilization and resource utilization of sludge.