Purification Effect And Mechanism Of Loessial Soil To Leachate

Landfill leachate control and treatment is one of the most important measures for prevention environment pollution. By survey, sampling and chemical analyses of landfill leachate of Xi'an Jiangcungou landfill, purification mechanism and effect of migration and transformation of Loessial Soil to pollutants in leachate are studied. Possibility and value of Loessial Soil as cover of Xi'an Jiangcungou landfill is discussed. The following conclusions can be drawn.1) The maximal absorptive capacity of topsoil,plow pan,clay layer,calcified layer of Loessial Soil to COD in leachate is 100 mg/g,120 mg/g,80 mg/g ,60 mg/g,respectively;The maximal absorptive capacity of topsoil,plow pan,clay layer,calcified layer of Loessial Soil to NH₄⁺-N in leachate is:26.12 mg/g ,13.75 mg/g ,13.24 mg/g ,10.76 mg/g.The maximal absorptive capacity of plow pan of Loessial Soil to COD is the highest for topsoil,plow pan,clay layer,calcified layer of Loessial Soil;And the maximal absorptive capacity of plow pan of Loessial Soil to NH₄⁺-N is the highest among topsoil,plow pan,clay layer,calcified layer of Loessial Soil.2) The oscillation time of soil sample reached the maximal absorptive capacity of topsoil,plow pan,clay layer,calcified layer of Loessial Soil to COD is 4 h,2 h,4 h,4 h respectively;The oscillation time of soil sample reached the maximal absorptive capacity of topsoil,plow pan,clay layer,calcified layer of Loessial Soil to NH₄⁺-N is 1 h,2 h ,2 h,2 h respectively.3) With the ratio of solution to soil increasing,the maximal absorptive capacity of topsoil,plow pan,clay layer,calcified layer of Loessial Soil to COD, NH₄⁺-N increase respectively.And the maximal absorptive capacity of clay layer soil,calcified layer soil of Loessial Soil to COD , NH₄⁺-N shows rapid growth trend.4) Removal rate and effect of thickness of soil layer on migration of COD is different. The maximum removal rate of 100cm thickness of the soil layer of COD is 100%;The maximum removal rate of 30cm thickness of the soil layer of COD is 92.31%;Maximum of 100cm thickness of the soil layer purified completely COD in leachate is 3575 mL,and range of COD removal rate is 100% to 89.28%.Maximum of 30cm thickness of the soil layer purified completely COD is 1750mL,and range of COD removal rate 92.31% to 69.23%5) Compared with topsoil,plow pan of Loessial Soil,the absorption capacity of clay layer,calcified layer of Loessial Soil to COD, NH₄⁺-N are relatively high.The clay layer,calcified layer of Loessial Soil as Xi'an Jiangcungou landfill cover has feasibility.By the specific conditions of operation,30 cm thickness of Loessial Soil is selected.The thickness of cover increases with seasonal structure in the production of leachate.