Study On The Pretreatment Of Landfill Leachate By Coagulation

Landfill due to technical maturity to deal with low-cost, management and transport convenience, is widely used. Leachate generated by landfill has poor water quality,which can produce severe pollution to wanter and soil. 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 thesis based on discussion group's previous experimental research, Collected the refuse from residential areas, selected and filled, and then landfill leachate was be produced.By coagulation test to choose the best reagent and working condition in COD and SS pretreatment effect.To ananlysis the toxic and hazardous substances changes before and after pretreatment in leachate,and analyze the cause of change.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 the pretreatment effect of coagulation on the leachate.The experiment results showed that the optimum conditions of the coagulation were coagulant PFC,dosage 600mg/L,the pH value 6.5,the mixing method 250r/min 1min 50r/min 10min,the PAM dosage 2ml/L,the temperature 20℃and 40min sediment time.Under the optimum conditions,the removal rate of CODcr was 28.6%,the removal rate of SS was 73.5% and the absorbance was 75.5%.According to orthogonal experiment and results analysis,in term of the removal rate of CODcr,the primary and secondary relationships of the coagulation factors which affect the leacheate treatment efficiency were mixing method, dosage of PFC,the initial pH value,dosage of NaCl and settling time. In term of the removal rate of SS, the primary and secondary relationships of the coagulation factors which affect the leacheate treatment efficiency were mixing method, the initial pH value, settling time, dosage of NaCl and dosage of PFC.According to GC-MS test results,the type,nature and content of organic in leachate changed little in before and after treatment.