Investigation into municipal waste leachate in the unsaturated zone of red soil

Abstract

There are many organic pollutants in the monitoring wells at Taichung sanitary landfill. The objectives of this study were to understand the leachate transport phenomena in this specific site, to identify the parameters, and to simulate the mathematical transport model of organic matters of leachate plume by SEFTRAN. The model uses the Galerkin's finite element method and its mechanism includes convection, dispersion, retardation, and biological decay. Consequently, this study investigated not only on the parameters of convection but also on the parameters of dispersion, retardation, and decay. In the laboratory, several significant pre-tests and filter selections were performed to standardize the testing process. The results show chloride is a good tracer and mercuric chloride is an excellent inhibitor for decay study in this case. The equilibrium time of soil organic matter's adsorption is less than 12 h. The half life of chemical oxygen demand for this methane phase leachate is 46 d. In the lysimetric study, the experiments simulated field conditions such as soil characteristics and groundwater temperature. The results show that the mean retardation coefficient is 2.05, and the dispersivity of the column is between 0.17 and 0.35 cm. In addition to the sensitivity study, parameter comparison was made to show Darcy's velocity is the most sensitive parameter.