Study On Operation Of Landfill Leachate Treatment With Process Of Membrane Technology

In this study, operation data and experience on a practical project of landfill leachate treatment with process of Membrane Biological Reactor (MBR, composed by denitrification & nitrification reactors and Ultrafiltration (UF) membrane)+Nanofitration (NF) Membrane are analyzed and researched; moreover, optimization conditions of operation and solutions of operation problems are summarized as following:(1) During commissioning, CODCr removal rate reached to 90% and effluent ammonia concentration is less than 5mg/l within one month, after adding sludge from other landfill leachate treatment plant into MBR, which is used as original sludge. Furthermore, sludge concentration increased to design value in 4 months.(2) In MBR, optimized pH range is 7.5-8.2, optimized DO range is 1.5-3mg/l, optimized sludge load on CODCr is around 0.1 kgCODCr/kgMLSS.d. Under such conditions, CODCr removal rate is over 75%, NO3ˉ-N in effluent is less than 300mg/l, NH4+-N in effluent is less than 2mg/l. BOD5/CODCr in leachate increases more, leading to better treatment effect in MBR. BOD5/CODCr should be more than 0.5. When CODCr/NH4+-N in leachate is more than 4, CODCr removal rate could get to above 60%, and NO3ˉ-N in effluent is less than 300mg/l。(3) Sludge concentration is not the major factor while sludge quality is on UF membrane operation. The highest UF permeate flow is 20m3/h in one loop of UF, turbidity in permeate is less than 1NTU. UF permeate flow might be lower than 10m3/h unless CODCr removal rate could get to over 60%. To do chemical cleaning on UF membrane with solutions of HCl+ NaClO+NaOH, is effective to increase UF permeate flow.(4) CODcr removal rate of NF membrane is more than 96%, SO42- removal rate is more than 97%. However, only avg.25% removal rate of TDS occurs,1 and nearly none Clˉis retained by NF. CODcr in NF effluent keeps below 90mg/l, meeting with requirement of discharge standard in class one. Pressure drop is most direct to judge pollution situation on NF. To do chemical cleaning on NF with solutions of HCl+NaOH+EDTA+NaHSO3, is effective to reduce pressure drop.(5) Solutions should be taken to solve issues in leachate treatment system with process of MBR+NF, such as, too much foam in system, accumulation on hard CODCr, not many choice on NF, and TN not meet with new standard.