Research On Modeling Of Optimal Groundwater Remediation Based On Energy,Envrionment And Health

Pump and treat(PAT)is one of the most widely-used remediation techniques in groundwater management.The favorable remediation scheme of PAT is due primarily to its advantages of simple technology,high reaction speed,and high remediation efficiency.However,PAT would hardly achieve the remediation goal if some flaws existed in the decision-making process.An optimization technique should be consequently merged into the groundwater remediation system before conducing the PAT schemes,which could not only significantly reduce remediation cost but also guarantee the remediation performance.Moreover,health risk currently has received much attention.In the previous researches associated with environmental remediation,some scholars have modelled the health risk as a special environmental constraint for generating a more humanitarian remediation performance.This study presents the groundwater remediation optimization design based on dual constraints of environmental standard and health risk.It could greatly protect human health and then contribute to social sustainable development.Uncertainty treatment in the process of groundwater remediation simulation and optimization could improve the reliability and effectiveness of decision making,and thus avoid remediation failure or excess.The application of hybrid energy,including renewable energy,is an effective tool of reducing cost in groundwater remediation engineering,whose principles are environmental protection and remediation.(1)Groundwater environmental is more complex than surface water due to the great concealment and hard repairability of groundwater contamination.In order to obtain more data and intuitively display groundwater environment,it is necessary to use numerical simulation for predicting and analyzing the water flow and contaminant migration.However,low computational efficiency and huge calculated amount are the major weaknesses for traditional simulation methods.Therefore,stepwise quadratic response surface analysis is introduced to establish surrogate equations.Statistical test is then used to verify and ensure the reliability of surrogate equations.Nonlinear groundwater remediation optimization model is finally developed based on stepwise quadratic response surface analysis.The parameters of hydrogeology and remediation strategy are treated as modeling inputs,and contaminant contaminations representing remediation performance are r egarded as modeling outputs.The relationships between inputs and outputs could be reflected based on the simulation of contaminant migration and transformation.Results show that this approach has the advantages of increasing accuracy of groundwater simulation and advancing computational efficiency when sufficient groundwater data could not be obtained.(2)On the basis of the research results of surrogate model,an optimal manage model of PAT is established.The model firstly considers the influence of environmental standards and remediation durations on optimal decision making.There is a big difference of environmental standards in countries,regions and water functional areas.In addition,the distribution of pollutants in groundwater is also uneven due to occurrence forms of groundwater and subsurface condition.In this study,a series of environmental standard gradient and remediation duration are set.Fuzzy set method is introduced to deal with uncertainty constraint,and all kinds of remediation schemes have corresponding satisfaction index.The results show that the proposed optimization model can put forward optimal remediation scheme under various remediation scenarios;more diverse remediation schemes can be output under the fuzzy environmental standard constraint;a greater value for flexible indicators has less impact on remediation schemes.(3)The health risk assessment system is introduced into the groundwater remediation optimization model,and some parameters with fuzziness and randomness uncertainties are solved.The influence of parameters uncertainties on decision making and remediation effect relevant indicators(such as health risk level)is analyzed,and results can provide data support and decision making basis for policymakers.Under the same series of environmental standard gradient and remediation duration,contrastive analyses are conducted on the effectiveness of the environmental standards and health risk constraints,health risk parameters uncertainties considered or not,and the importance order of health risk assessment parameters.The results show that the introduction of health risk assessment system can recover neglect of human health under relaxed enviro nmental standards;considering uncertainties in health risk parameters will lead to the rise of remediation costs,but health risk levels drop significantly;in the uncertain parameters influencing the health risk levels,exposure frequency is the most imp ortant parameters and makes the biggest influence on remediation schemes.(4)In the previous studies,in order to control the cost,most researchers tend to optimal the remediation scheme or combine long period but cost-effective repair method into a PAT system.These studies aim to reduce pumping rate as much as possible within the scope of restrictions.However,the save is likely to cause the remediation effect reduced and even cause human health risk.This study intends to take a new perspective,an optimization model based on health risk constraints and hybrid energy system is proposed.The model is presented to seek optimal use of traditional,renewable energy,and provide the optimal remediation scheme suggestion for decision makers under various remediation scenarios.According to the study results of two real sites,traditional energy played the leading roles for a short-term remediation,while solar energy gradually replaced the traditional energy due to the cost collection of renewable energy construction.In the 4 kinds of remediation durations in Canadian case,the 10 years schemes have balance and relatively stable performances in health risk level,pollution and cost control.Therefore the 10 years schemes by using hybrid energy system are the optimal choices in Canadian case.The 7 years schemes by using hybrid energy system are more suitable in Chinese case.