Method of evaluating the impact of landfill leachate on groundwater quality

Closed municipal and industrial waste landfill sites create potential hazard of ground water pollution. Pollutants that occur in leachate infiltrate to the soil substratum, where they are carried to in underground water. A municipal waste landfill substratum can be used for elimination of pollutants contained in leachates. Model research was performed with the use of a sand bed and artificially prepared leachates. Efficiency of filtration in a bed of defined thickness was assessed based on change of COD value. Results of the model tests have indicated that the mass of pollutants contained in leachate filtered through porous ground layer depends on the mass of supplied pollutants, intensity of supplied leachate, and layer thickness. Increase of the mass of pollutants supplied to a unit area of ground layer causes reduction of the relative value of COD mass. The method of evaluation of quality of water seeping through the aeration layer presented in this paper allows for estimation of the flowing out pollutants mass. Based on the test results obtained, efficiency of purification in the aeration zone can be assessed; likewise, safe thickness of the filtration layer under the landfill site can be designed.