Study On The Treatment Of Landifill Leachate

Landfill leachate, produced in the process of sanitary landfill disposal, contains high concentration of pollutants and great variation is often observed in both water quality and quantity. So it is a difficult problem in worldwide field of wastewater treatment. This study was conducted to develop an effective process for landfill leachate treatment; therefore a full-scale test using biochemical-physicochemical process and a pilot-scale test using membrane bioreactor-nanofiltration process were carried out on Laohukeng landfill site, Baoan district of Shenzhen city. Experimental results show:( 1) Biochemical-physicochemical process was used to treat Laohukeng landfill leachate in a full scale. 81.3-90.8% of COD and 63.4-75.4% of NH₃-N were removed when raw leachate contained 4888-8365 mg-COD/1 and 1239-1683 mg-NH₃-N/l and the HRT was kept at 49.9-68.7 h. The effluent can meet to the third discharge limit of landfill leachate(COD< 1000mg/L, NH₃-N unlimited).(2) Membrane bioreactor-nanofiltration process was used to treat Laohukeng landfill leachate in a pilot scale. When raw leachate contained 10900-13000 mg-COD/1 and 2330-2910 mg-NH₃-N/l, 99.4-99.8% of COD and 99.7-99.9% of NH₃-N was removed at the temperature of 29-32 ℃, pH of 6.7-7.2, organic loading rate of 0.10-0.17 kgCOD/(kgMLSSd), ammonium-N loading rate of 0.02-0.04kgNH₃-N/(kg-MLSS·d), recycling ratio of 9.5-25.1. The effluent can stably meet to the first discharge limit of landfill leachate(COD<100mg/L, NH₃-N< 15mg/L).(3) By the discussion of technique and economy, it is sure that membrane bioreactor-nanofiltration process with many advantages in efficiency, stability, area, autocontrol, operation, and economy is a new-style technology suitable for the treatment of Laohukeng landfill leachate.In summary, this study solves the difficult problem of Laohukeng landfill leachate treatment successfully. Membrane bioreactor-nanofiltration process has instructional function and practical value, and it could be used to treat leachates similar to Laohukeng landfill site.