Sustainability Analysis And Decision Optimization Of Soil Remediation Alternatives For Contaminated Sites

Soil pollution caused global degradation of soil function and endangered the foundation of human existence.The rapid global growth of the soil remediation industry has made it a socio-economic activity that has a huge impact on humanity.To better promote the development of the soil remediation industry and improve the remediation effect while reducing the consumption,the sustainability of soil remediation has attracted the attention of all sectors of society.The objective of sustainable soil remediation was to addressed soil pollution while minimizing negative socioenvironmental and economic impacts and making the activity sustainable.Providing a theoretical basis and technical support for the sustainable development of soil remediation,i.e.,the construction of a sustainability evaluation system for soil remediation and the development of sustainability analysis methods and tools for soil remediation are the main needs at this stage of the research field.Life Cycle Assessment(LCA),a method of environmental impact measurement and analysis from a life-cycle perspective,is the main research method for sustainable soil remediation,which can quantitatively analyze the environmental impact of soil remediation and evaluate the sustainability of soil remediation based on environmental impact.However,there was a lack of quantitative analysis of socio-economic impact,and there was a need and space for improvement.In this study,a typical chemical industry contaminated site was studied,the LCA method and the Input-Output Life Cycle Assessment(IO-LCA)method are applied to the sustainability evaluation of soil remediation technologies,and the MADM method was developed for sustainable soil remediation technology programs through Multi-Attribute Decision Making(MADM)based on the indicators of the two life cycle methods.The method applied to soil remediation alternative decisions based on sustainability comparison.This methodological system provided new ideas for sustainable soil remediation and has important positive implications and reference value.The study divided into the following four parts.In the first part,a life cycle model of the soil remediation alternatives for contaminated sites in the study area was developed through the LCA software Sima Pro9.0,the environmental impacts of the alternatives were assessed and analyzed,and uncertainty analysis of the model was carried out.The assessment showed that:(1)the environmental impact of the soil excavation transport phase and the sewage treatment phase of the site was much less than that of the soil remediation technology treatment phase.(2)The environmental impact of soil remediation technologies is greatest for insitu thermal desorption(ISTD),followed by in-situ thermal desorption(ESTD),and least for in-situ encapsulation(ISE).(3)Alternative 2(ESTD+ISE)is the least environmentally impactful;Alternative 4(ESTD+ISTD)is the most environmentally impactful.(4)The environmental impact of ISTD technology is mainly from the electricity used to maintain the operation of the equipment;the environmental impact of ESTD technology is mainly from the natural gas consumed to heat the thermal energy supply of the soil,and the environmental impact of ISE technology is from the gelling material used to construct the barrier wall.(5)The environmental assessment results for alternative 1(ISE+ESTD+ISTD)are subject to a high degree of uncertainty,and the relationship between its score and that of alternative 3(ESTD)varies between scenarios.In the second part,the integrated environmental and socio-economic impacts of the soil remediation project are quantified first through the IO-LCA(Input-Output Life Cycle Assessment)method,which includes an inventory of pollutant emissions,employment and economic impacts of the soil remediation project.The lack of characterization of the IO-LCA method of environmental impact assessment was then improved by characterizing and empowering the inventory in conjunction with the Re Ci Pe environmental impact assessment model to obtain the impact assessment results.Finally,an uncertainty analysis was performed,and the environmental impact on socio-economic benefit ratios of the various alternatives/technologies were compared.The assessment shows the relationship between the environmental impact and socio-economic effects of the alternatives:(1)ISTD technology has the largest environmental impact and produces the most socio-economic effects among the three technologies;ISE technology has the smallest environmental impact and produces the least economic effects,and ESTD technology has the largest socio-economic effects among the three technologies.(2)Environmental impacts and socio-economic effects of ISTD technologies come mainly from nine industries: gas production and supply,electric heat production and supply,metal smelting and rolling products,non-metallic mineral products,chemical products,petroleum,coking products and nuclear fuel processing products,oil and gas extraction,coal extraction products and non-metallic ore and other mineral extraction products.In the third part,the MADM method for sustainable soil remediation alternative was developed by weighting the LCA environmental impact assessment indicators and the IO-LCA socio-economic impact assessment indicator system through the hierarchical analysis in the MADM method system and applied in practice.The results of the decision alternative show that:(1)Alternative 2(ISE+ESTD)is the most conservative and sustainable soil remediation alternative.(2)ISE technology is the most sustainable of the three technologies.In the fourth part,the design scenario simulation through LCA and IO-LCA was used to perform comparative analysis and make optimization recommendations using the MADM method.The following conclusions are based on the above study:(1)Conversion of electricity supply to wind power can significantly improve the sustainability of soil remediation alternatives.(2)The use of heavy-duty trucks for soil transport during the construction of soil remediation can improve the sustainability of soil remediation technical alternatives.(3)In the production of soil remediation materials,the choice of heating energy for material preparation is a major influence on the sustainability of soil remediation materials.Coal heating is a less sustainable form of heating(4)The development of a screening matrix for soil remediation solutions with sustainability indicators and the introduction of Remediation Process Optimization(RPO)can facilitate the development of sustainable soil remediation.