| Sanitary landfill is the main process of the municipal solid wastes (MSW)treatment, and it will produce landfill leachate certainly. The landfill leachate is very harmful for the environment, therefore, we must solve this problem. Landfill leachate is a complex wastewater with considerable variations in composition, and high concentration of COD and NH3-N. The composition and concentration of contaminants are influenced by the type of wastes deposited, by hydrogeological factors and mainly by the age of the landfill. This investigation aims to study physical, chemical, biological characteristic of landfill leachate and characteristic of biological treatment of landfill leachate, which was sampled from Jiangcungou Sanitary Landfill of Xi'an City. The results of experiment can be used as evidence and reference to when choosing methods for treatment of Jiangcungou's landfill leachate.There are five experiments below: study on characteristics of molecular weight fraction of landfill leachate; study on biodegradability of landfill leachate; study on characteristic of anaerobic biologic treatment of landfill leachate; study on characteristics of molecular weight fraction of treated landfill leachate; research on the treatment characteristics of landfill leachate by anaerobic baffled reactor(ABR). We got the conclusions base on these experiments as follows:(1) The result of study on characteristics of molecular weight fraction of landfill leachate showed the fractions of landfill leachate were found to be narrowly at the range of less than 10,000Da, which were accounted for about 86.90% of total pollutants.(2) During the study on biodegradability of landfill leachate, I found that the value of BOD5 of landfill leachate was 39.08% and BOD/COD of landfill leachate was 39.08% which showed that landfill leachate could not be well treated in biological treatment. In the continuous BOD experiment, we calculated the datum and got the possible maximum removal rate of biologic treatment of landfill leachate, which is 57.8%.(3 ) When anaerobic SBR treated landfill leachate, the results showed that the concentrationof free ammonia is the main inhabitation factor of anaerobic treatment. When pH value in the reactor was adjusted to 7, the concentration of free ammonia in reactor is less than 40mg/L, and the quantity of gas production kept inl 000-1500ml. The results showed that the inhabition of free ammonia is recoverable.(4) The molecular weight fraction of effluence of A, B anaerobic SBR reactors showed that the molecular weight of pollutants would increase after the anaerobic treatment. At the range of less than 10,OOODa, the COD of leachate descented from 77.71% before the inflow to 69.96%~72.44% after the effluence; and TOC descented from 86.90% before the inflow to 70.00%~78.52% after the effluence. Anaerobic SBR mainly removed small molecular, so aerobic biologic should not used as step-treatment.( 5 ) When the landfill leachate was treated by using ABR, COD of inflow was 6500 mg/L, removal rate was 82 %; as the concentration of landfill leachate increased to 9000 mg/L, removal rate was 69 %. the reason is that the increase of concentration of free ammonia inhabited the activity of biologic. By the comparison of ABR and SBR, it shows that the effect of ABR treatment is worse than SBR treatment. The reason is that the anti-striking capability of ABR is worse than the SBR. The removal rate of No.l compartment was 60-80% of total removal rate. Therefore when ABR was stricked, total removal rate will decent with No.l compartment.(6) Accroding to the experiment results, sequent process should choose the phychemical process after anaerobic treatment.
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