[Contamination removal in landfill leachate by biological effect in sand layer of vadose zone]

Through the test of two sand columns for comparing, the effect on removal of pollutants in landfill leachate by biological effect in sand layer of vadose zone was studied. First, HgCl2 was confirmed as inhibitor of biological effect, and its most suitable concentration was 10 mg/L. Then, sand column 1 was leached by landfill leachate, and sand column 2 was leached by landfill leachate added 10 mg/L HgCl2. The results indicated: with the time prolonged, the biological effect was more and more obvious. When the test was finished, the concentrations of COD and BOD, respectively reduced by 2724 mg/L and 2332.5 mg/L, and the concentration of NH4+ ascended from 1282.82 mg/L to 1745.48 mg/L, but the effect of TN removal was not obvious. Because the biological effect was inhibited by inhibitor of HgCl2 , the concentrations of pollutants kept calm when landfill leachate penetrated the sand column. Based on the results of experiment, the first-order attenuation kinetics model of biodegradation in sand column was founded.