Municipal Solid Waste Landfill Leachate Pretreatment Study

Sanitary landfill is the main process of the municipal refuse treatment, and it will produce landfill leachate that is very harmful for the environment. The landfill leachate is a complex wastewater with considerable variations in composition, and high concentration of COD,heavy metal ion and ammonia-nitrogen. Pollutant concentration of the landfill leachate used to change largely. If the landfill leachate is discharged into the environment, the soil and groundwater environment will be polluted severely. Currently, all of the processing craft in domestic and foreign are divided into three segments; the biological treatment is taken as the main body craft, the physical-chemical treatment and land method are taken as the pretreatment craft and the post-processing craft, respectively.The experiment mainly imitated the process of the sanitary landfill of the municipal refuse. Collected the refuse from residential areas, selected and filled, and then landfill leachate was be produced. Analyzed and contrasted the characteristic of the simulant leachate. And some of the physical-chemical pretreatments that were chosen to deal with this leachate were to be studied.By analyzed the water quality of the simulant leachate, the characteristic of variations in composition,high concentration of COD and ammonia- nitrogen was found from the simulant leachate, so we thought that this leachate would replace the practical leachate. And through the whole process of physical-chemical pretreatment, we found that the particle diameters of main contaminants were less than 1nm in this leachate.The paper studied four kinds of pretreatment methods, which were coagulation, adsorption filtration by activated carbon, chemical precipitation method and Fenton oxidation process. The experiment results showed that the optimum conditions of the coagulation were coagulant PAC, the pH value 7.5～8.0, doses 400～800mg/L, stirring rate 150rpm, mixing time 20min, sedimentation time 45min. Under the optimum conditions, the removal rate of COD_cr was 20.10%, the removal rates of SS and chrominance were 80.53% and 93.75%, respectively. But odors and ammonia- nitrogen of the leachate were not nearly removed.Under the properly conditions of adsorption filtration by activated carbon, the COD_cr was removed highly, reached about 70%, the removal rate of chrominance was 50%, the ammonia-nitrogen was not nearly removed.Using the function of magnesium ammonium phosphate to remove the ammonia-...