Analysis Of Vertical Differertial Sulfate Reduction Behavior In Landfill

The material distribution caused by vertical migration of leachate in landfills leads to different internal environment,and the sulfate reduction behavior causing odor is different obviously.Clarifying the vertical differential sulfate reduction behavior in landfills is expected to provide accurate basis for the treatment of the source of sulfur-containing odorous pollution in landfills.In this study,the vertical differential sulfate reduction behavior of landfills was analyzed step by step from the perspective of sulfate reduction potential characterization,static distribution analysis of vertical sulfate reduction characteristics,dynamic evolution of sulfate reduction caused by leachate,etc.,in order to provide theoretical basis for the control of the odor source containing sulfur in landfill.Firstly,landfill waste samples from different landfill areas of actual landfills were collected and analyzed according to landfill age classification to characterize the sulfate reduction potential of differentiated landfill age waste.The study found that with 12 m as the limit,when the landfill depth is less than 12 m,the H₂S release intensity of 0-6 m is relatively severe;when the landfill depth is more than 12 m,the H₂S production intensity of 9-12 m is much greater than that of other landfill layers,and the maximum H₂S release concentration of all sampling points is close to the instantaneous lethal concentration（1000 ppm）.The cumulative H₂S production of landfill can be evaluated by the first-order dynamic model.With the increase of landfill depth,the possibility of secondary H₂S release caused by biological sulfate reduction in landfill will gradually increase.Secondly,the laboratory simulated the differential landfill age scenario to track and analyze the static difference of sulfate reduction behavior in top-down vertical stratified landfill waste.It was found that the H₂S release behavior decreased with the increase of landfill depth,and the peak concentration of H₂S release in surface area（34.32 mg/m³）was three times as high as that in deep area（10.24 mg/m³）.MM and DMS were detected only on the superficial surface and released to concentrations as high as 1884.57 mg/m³ and 665 mg/m³,much higher than the dangerous concentrations for humans.In the surface layer,Bacillus,which had sulfate reducing function,dominated the sulfate reduction process.Desulfuromonas,Desulfofustis,Thioalkalispira-desulfurivermis,Dethiosulfatibacter and Desulfococcus are the key species mediating sulfate reduction behavior in the deep and middle landfill.Finally,based on static differences,vertical series differential landfill age scenarios were selected to simulate the top-down migration process of leachate and explore the dynamic response of sulfate reduction behavior of leachate during the top-down migration process inside the landfill.It is found that there is a differential metering relationship between electron acceptor(SO₄^2-)and electron donor（COD,TOC）consumption when leachate migrates to different landfill layers.Desulfobulbus and Desulfotignum in the landfill surface（R1）and shallow（R2）layers for sulfur metabolism processes,Desulfuromonas and Thioalkalispira-Sulfurivermis are the dominant species mediating the sulfate reduction behavior in the middle level（R3）and deep level（R4）landfill.