| With the increase of urban population, the enlarging of the urban scale and the exaltation of residents' living standard, the output of municipal solid waste increase dramatically. Now, sanitary landfills is the mainly method for the municipal solid waste treatment at home and abroad, above 90 percent of municipal solid wastes are treated by this method in China. Landfill leachate is a kind of secondary pollutant as a high concentrated organic wastewater, which come from the stack and landfill of waste. As a byproduct of waste treatment which is a kind of wastewater with high concentration, multicomponent, non-uniform flow and its quality changes greatly. Some investigation point out that this kind of waste water contains many kinds of toxic substances and cancer-causing substances, it needs 15 years to degrade the COD and BOD to the state discharge standard under the natural conditions. It will cause serious pollution to the environment if the landfill leachate can not be well treated. It is generally acknowledged that the treat of landfill leachate is a difficult international problem. And the problem has a serious impact on the healthy development of our treatment of landfill leachate.The treatment of landfill leachate at high and moderate temperatures is effective in treating the landfill leachate and it has been applied in the industrialization. But the treatment at normal and low temperatures is not adequate.In this paper, the characters and the treatment technology of landfill leachate are studied, an optimization process of regulating tank ammonia stripper+UASB+SBR+filtration +coagulative precipitation possesses to treat the landfill leachate at normal temperature was proposed. There are two advantages:(1) stable operation and low cost. (2) It will be positive in reforming the existing treatment plants of landfill and improve the landfill and the surrounding environment, because most of the existing treatment plants of landfill use stripping+anaerobic+aerobic treatment process.By the optimal test of each treatment unit and the analysis of treatment efficiency by the combination process, conclusions are elicited as follows:(1) The optimum techniques parameters of the treatment of landfill leachate by ammonia stripper are determined by the miniature test and ammonia blowing-out, the parameters as follows:Dosage of limes 10g/L, pH 10.5～11, time of ammonia stripper 8h.(2) The main influencing factors of ammonia stripper includes pH, time of ammonia stripper and air intake, the effect of ammonia concentration on ammonia stripper efficiency is limited.(3) The addition of PAC can shortening the UASB start-up time by 1/3 and raising the organic loading by 60% than the comparable UASB without PAC, and the stability of UASB was improved. The addition of PAC can enhance the activity of granular sludge not for the gross of microbial.(4) The temperature is a very important factor for the UASB, because the activity of granular sludge is sensitive to the change of temperature. Test results show that in the UASB by addition of PAC, the organic loading reach to 25 kgCOD/ (m3·d) and can reach better treatment effect above 15℃when treat high concentration wastewater.(5) The sludge pellet in the reactor with PAC had larger diameter and higher activity than one in the reactor without PAC. The methanogentic activity in 2# react tank is higher than the 1# tank, the maximum discrepancy is above 40%.(6) Lower pH is favourable to the stable of granular sludge structure, the increase of proton transfer activity and the decrease of acidity of surface of bacteria.(7) Loading has great impact on the start-up of UASB, the increase of the volumetric lading had better to being on the base of VFA and the VFA had better to be kept below 300mg/L.(8) At the beginning of the SBR start-up, the removal rate of NH3-N is low which show that the culture of nitrobacteria population need a long time.(9) The removal of NH3-N and TN is better in the condition of Aeration/Aerobic/ Aeration/Aerobic, batch throwing the intake water before the Aeration in the ratio of 2:1, ratio of discharge of 1/3, and intake water pH 8.0. The character of intake water is COD 2759mg/L, NH3-N 685mg/L,TN,710mg/L.The removal rate of COD, NH3-N and TN is 71.7%,92.4%,69.8% in respectively.(10) The FeCl3, FeSO4, PAC and Al2 (SO4) 3 are decided as the factors, the orthogonal test of 4 factors and 4 levels show that the FeCl3 is better in COD removal than the other coagulants. The result show that the settling of floc from ferric salt coagulantis is superior to aluminum salt coagulants(11) The FeCl3 is decided as coagulant. The result of orthogonal test of 3 factors and 3 levels show the order of factors that affect the coagulative precipitation efficience is:Initial pH> dosage of coagulant> dosage of PAM and the range of value are elementally determined.According to the above orthogonal test, the result of one element experiments show the optimal values as follows:pH=5, dosage of coagulant 500mg/L, dosage of PAM 4mg/L。(12) The ceramic mediums and quartz sand are chose as filter materials. The result of orthogonal test show that the removal of COD and turbidity is not very well and direct filtration cannot significantly reduce the pollution degree of the landfill leachate which has been biochemical treated, because the suspension matter is less after the second biochemical method, large size suspension matter are broken by the SBR, and a great deal of bulbs are unfavorable to the direct filtration. For the landfill leachate treated by the second biochemical method, the optimum scheme of the direct filtration by ceramic mediums is particle size of filter media 1.6～2.0mm, filtration bed thickness 700mm, filter velocity 6 m/h, and the optimum scheme of the direct filtration by quartz sand is particle size of filter media 1.25～1.6mm, filtration bed thickness 800mm, filter velocity 4 m/h, the ceramic mediums have a better filtering quality than quartz sand.(13)The coupling technique of ammonia strippe+UASB+SBR+filtration+ coagulative precipitation possess of better flexibility for the treatment of landfill leachate which is a kind of wastewater of very complex, high ammonia concentration, severe pollution and less emission. The technique has higher organic load and each process has powerful resistance to impact load, it shows a good potential of popularization.
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