| The landfill is the main facility for the centralized disposal of hazardous waste,and it is also a place where environmental pollution occurs.Hazardous waste landfills still have leakage problems under the action of atmospheric precipitation leaching,causing serious harm to the surrounding groundwater environmental system.Therefore,the construction of a complete set of hazardous waste landfill pollutant transport model system is of great significance to the long-term maintenance and management,environmental risk prediction,and risk control of hazardous waste landfillsIn this paper,the current research on the transport of pollutants in hazardous waste landfills has problems such as "system has not yet been established","multiple leakage sce-nario" and "inaccurate consideration of parameter randomness".It focuses on the "basic construction of hazardous waste landfill pollution".The core goal is the material transport model system,and the comprehensive use of theoretical analysis,on-site testing,and numer-ical simulation.A total of four areas of work were carried out,namely the construction of a mathematical model of pollutant transport in hazardous waste landfills,the establishment of a three-dimensional model of complex seepage source strength coupled with groundwater and solute transport in vadose zones,and the impact of parameter uncertainty on groundwa-ter pollution risks Characterization and development of a pollutant transport model system for hazardous waste landfills,specifically:(1)B ased on the study of landfill leakage theory,pollutant transport mechanism,empir-ical formula and field investigation,five mathematical models of surface water infiltration,rainwater drainage and seepage prevention,heap leaching,leachate drainage and seepage prevention,and groundwater in vadose zone are established.It accurately describes dozens of surface and underground hydrological processes,including surface runoff,surface water infiltration,heap infiltration,leaching,lateral drainage of leachate,leachate leakage,water flow and solute transport in vadose zone,and water flow and solute transport in groundwater aquifer.(2)The nonlinear equations of groundwater flow and solute transport in the vadose zone groundwater model are solved by the finite element method.The three-dimensional dynamic migration process of pollution source in groundwater in vadose zone and the change of pollutant concentration with time in monitoring well are analyzed.The cor-rectness of groundwater model prediction in vadose zone is verified by the change law of pollutant concentration in groundwater.(3)Based on the MySQL+Python+PyQt5 development framework,a pollutant trans-port model system for hazardous waste landfills was developed,and the uncertainty of the parameters was analyzed using the Monte Carlo(MC)method.Relying on the actual data of a hazardous waste landfill in Beijing,the results of comparison with the HELP-Landsim coupling model show that the total cyanide(T-CN)concentration in the water at the haz-ardous waste landfill is 50%and 90%.,95%confidence level,from the"increasing slowly "in the early stage of landfilling,to the " significant rise" in the mid-term,and then to the" flattening"in the later stage,and the pollutant migration obtained by the HELP-Landsim coupling model The law is the same.And the maximum absolute error of the concentration of T-CN and Free Cyanide(F-CN)per year does not exceed 0.2268 1mg/L.In addition,the time for the concentration of T-CN and F-CN to exceed the limit of groundwater quality standards at 50%,90%,and 95%confidence levels differs from the time of exceeding the limit of the HELP-Landsim coupling model by less than 3%.Reflected the better risk early warning characteristics of this systemThe research results of this paper show that the pollutant transport system of hazardous waste landfills has higher accuracy and better presentation for the description of the basic landfill pollutant transport process,as well as higher engineering reference and application value. |
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