| Industrial wastewater contains a large number of highly toxic and refractory organic pollutants.Chemical oxidation pretreatment or advanced treatment can ensure that industrial wastewater treatment meets the discharge standards.Fenton process and its derivative technology and combined improvement technology have been widely used in various industrial wastewater treatment processes and achieved good treatment results.Life Cycle Assessment(LCA)refers to the compilation and evaluation of inputs,outputs and their potential environmental impacts in the life cycle of a product system.Since 1990 s,life cycle assessment(LCA)has been widely used in the field of wastewater treatment,and the treatment system of industrial wastewater is one of the main objects of its evaluation.In this study,it was found that the LCA analysis of Fenton treatment process was lacking in the existing studies related to the LCA evaluation of industrial wastewater.In addition,most of these studies are based on the laboratory stage of the process equipment,and there are few case studies based on actual industrial wastewater treatment plants.Therefore,the purpose of this study is to compare the environmental loads of two Fenton processes based on the industrial wastewater of a pharmaceutical factory by LCA.The two processes are homogeneous Fenton process and heterogeneous Fenton process.At the same time,four optimization schemes of heterogeneous Fenton process are proposed in order to find a better alternative to homogeneous Fenton process.Firstly,the energy and material consumption of the two processes were analyzed by LCA.It is found that the simultaneous use of hydrogen peroxide and sodium hydroxide is the main factor causing the environmental load of material consumption in homogeneous Fenton process,while the main factor causing the environmental load of material consumption in heterogeneous Fenton process is hydrogen peroxide.The energy consumption and environmental load of the two processes are mainly caused by the consumption of heat energy.Further comparing the two processes,we found that the evaluation results of heterogeneous Fenton process in most environmental factors were higher than that of homogeneous Fenton process,such as 45.94%,1.73%,50.49% higher in agricultural land use,fossil fuel consumption,freshwater ecotoxicity,freshwater eutrophication and other environmental catalogues,respectively.10.43% wait.Through the analysis of background material contribution,it can be seen that the heterogeneous Fenton process has higher resource consumption and material release than the homogeneous process in the whole life cycle operation stage,such as producing obvious ammonia release(increased by 104.03%),releasing higher nitrogen oxides(increased by 32.05%)and consuming more than the homogeneous process.Copper metal resources(increased by 77.42%)and so on.In order to find a solution with the lowest environmental load and can replace the homogeneous Fenton process by LCA analysis,four improved schemes for optimizing heat sources are proposed for heterogeneous Fenton process.The results show that Hete＿optimization scheme 2,i.e.the scheme of incineration of thermal energy in municipal sludge,produces the lowest environmental load for all the environmental factors investigated.Compared with the homogeneous Fenton process currently in operation in the case pharmaceutical factory,Hete＿optimization scheme 2 has lower assessment results in resource consumption,human health,ecosystem quality and total environmental load,reducing 17.71%,1.40%,34.58%and 13.21% respectively.Therefore,when the thermal energy of heterogeneous Fenton process can be derived from municipal sludge incineration process,from the life cycle point of view,heterogeneous Fenton process can be used to replace the homogeneous Fenton process in the case. |
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