Experimental Testing On The Permeability And Transformation Of Pollutants Of Landfill Leachate In Loess Columns

The exudates from the landfill of municipal domestic garbage produce water of very disgusing quality and their chemical compositions are complicated. The influence on the surrounding environment and underwater has drawn increasing attention. Since the past decades ,many studies has been conducted with foucus on the quantity and quality of the contaminants derived from landfill leachate ,and their formation mechanism and disposal technologies. However, few information is available about the experimental testing on the permeability and transformation of pollutants of landfill leachate in loess columns. The leaching experiment of Ma Lan loess column mainly probe into infiltration characteristic and transformation action of pollution (NH₃-N and organic pollution etc) compared with rinsing and domestic sewage. The study analyzed the reciprocity between leachate and loess and transformation theory of pollution.By comparing the continuous experimental testing of trends of infiltration leachate (1～5,7,9,rinsing (6) and (8,10) municipal domestic wastewater in loess columns, the following findings may be concluded that: (1) the trend of leachate infiltration appeared to fluctuat in all columns;(2) the infiltration rate of leachate was lower than that of rinsing columns and municipal domestic wastewater columns. The infiltration rate of the number 1 to 3 and number 7 appeared upward and the infiltration rate of the columns of number 4,5 and 9 was smaller and not augmenting; the infiltration rate of the columns of number 6,8 and 10 was larger but not appeared increscent phenomenon. The characteristics of infiltrating materials were the dominating factors controlling the movement of infiltrating materials. The factors that influenced the leachate infiltrating variation included microorganism action, water-rock interaction, adsorption, filtration, etc. Then the leachate may penetrate through the loess and polluting the groundwater seriously.The test discussed transformation of NH₃-N and organic pollution etc of leachate at the same time of studying the penetrability of loess. The results showed that removal of NH₃-N mostly happened earlier twenty days of test and that the attenuation action mostly depended on adsorption of loess particulate, but biodegradation action was unconspicuous. Comparing with NH₃-N, the attenuation of organic pollution mostly depend on adsorption of loess particulate and biodegradation action. The adsorption of NH₃-N was better than that of organic pollution in loess. The removal rate of NH₃-N was higher than CODcr in prophase of test, then failed rapidly when the columns adsorbed saturation, but the organic pollution kept upper removal rate in a long time, thereout the test also proved that the biodegradation action of organic pollution was better than that of NH₃-N.