Design And Operation Characteristics For Upgrading And Reconstruction Of Leachate Treatment In A Domestic Waste Landfill On The South Bank Of Taihu Lake

The landfill leachate contains refractory organics,complex inorganic salts and heavy metals that are toxic to microorganisms.If mishandled,it will cause serious environmental pollution to soil and groundwater.The original treatment process of leachate in a landfill site on the south bank of Taihu Lake is anoxic-aerobic（A/O process）,with low removal efficiency of COD and ammonia nitrogen,unstable operation effect and many other problems.The effluent is difficult to meet the current discharge standard of"Standard for Pollution Control on the Landfill Site of Municipal Solid Waste"（GB 16889-2008）.Based on the analysis of the existing problems of the original process,combined with the current mature technology of landfill leachate treatment and the mechanism of pollutant removal,this paper puts forward the transformation scheme of landfill leachate treatment.The transformation content mainly involves the following aspects:（1）the original hydrolytic acidification tank is changed into an anaerobic tower with UASB structure to solve the problem of low removal rate of COD;（2）the original A/O process is changed into two-stage A/O+MBR treatment unit to solve the problem of low removal rate of ammonia nitrogen and COD,while the MBR effluent can guarantee the subsequent NF/RO process;（3）increasing the NF/RO membrane treatment process to ensure that the final effluent COD and ammonia nitrogen meet the standard and solve the problem of inorganic salt and heavy metal pollution.Combined with relevant technical specifications and standards,the UASB anaerobic reactor,two-stage A/O-MBR nitrification and denitrification system and NF/RO membrane advanced treatment system are designed and calculated,as well as the equipment,civil construction investment and operating costs of the reconstruction project are estimated.UASB strains were acclimated by increasing COD load gradient,and the removal rate of COD by UASB could reach 60%within 60 days.The results of monthly and daily monitoring experiments for eight months show that when the influent COD and NH₃-N concentrations are 7668 mg/L～10130 mg/L and 1192mg/L～1674 mg/L respectively,the final NF/RO membrane advanced treatment process effluent concentrations are COD≤35 mg/L and NH₃-N≤2 mg/L,the effluent quality can meet the discharge standard Table 3 of GB 16889-2008.