Study On Flow Law And Regulating Measures Of Leachate And Landifill Gas In Municipal Solid Waste Landfills

With the increasing popularity of urbanization,the production of municipal solid waste in China is increasing day by day,and waste disposal has become an important issue in China and even in the world.The landfill method has become the most important way of municipal solid waste disposal in the world due to its large capacity and high applicability.Because of the complicated composition of waste,a series of extremely complex changes will occur in the landfill after the completion of landfill,and this process is usually called the landfill stabilization process.During this period,a large amount of biodegradable organic matter are explained in water,leachate and landfill gas is released,and the leachate contains many microorganisms and acidic chemicals.Therefore,if scientific control measures are not carried out in the stabilization stage of landfill,it will easily lead to a variety of environmental engineering problems such as leachate leakage,landfill gas explosion,uneven settlement and slope destabilization,which are significant safety hazards to the surrounding residents.In this paper,the multi-field interaction behavior of solid,liquid,gas and chemical in the stabilization process of municipal solid waste landfill in China was studied by numerical simulation to investigate the multi-field coupling mechanism of liquid-gas transport,compression deformation and solute migration based on biochemical degradation in municipal solid waste landfill.The research conducted and the results are as follows.(1)Based on the above studies,BHM coupled model(bio-hydro-mechanical coupled model)was constructed for MSW landfills with high food waste content in China.The model takes into account the effects of biochemical degradation and water content on the compression deformation of the solid phase skeleton,and simulates the effects of various control measures on several important indicators in the landfill stabilization process.The reliability of the model was initially verified by comparing the results with those of large landfill simulation tests.(2)The BHM coupled model of MSW landfill was applied to simulate the landfill by designing corresponding cases and analyzing the effects of different control measures on biochemical degradation,liquid-gas transport,compression deformation and solute migration patterns in the landfill by comparing five working conditions: surface leachate recirculation,vertical well leachate recirculation and pumping,blind trench leachate recirculation and pumping,and studying the effects of leachate leachate recirculation and pumping on the stabilization process of MSW with high food waste content in China.The effect of leachate recirculation and gas extraction on the stabilization process of municipal solid waste landfills with high food waste content in China was studied.(3)Parameter sensitivity analysis was conducted for vertical well leachate recirculation and pumping control measures,and 14 leachate recirculation conditions were designed,considering the effects of different vertical well spacing,vertical well depth,periodic leachate recirculation and in-well pumping on the liquid-gas transport patterns in MSW landfills.By setting different vertical well spacing,the reasonable distribution of landfill multi-well regulation was analyzed;by setting different vertical well depths,the effective depth of the vertical well was studied;by different periodic leachate recirculation and pumping,the influence of the leachate recirculation of period on the landfill stabilization process was analyzed.