The Study On Fenton-BAF Advance Treatment Of Landfill Leachate After MBR

Landfill leachate contains a high concentration of contaminant, some of the contaminantis refractory compound, conventional treatments can hardly make the effluent meet theemission standard. So how to treat the landfill leachate efficiently at lower cost is a hot spot inenvironment projection area.RO (reverse osmosis) treatment can get high-quality effluent, but its disadvantages likehigh operation cost and high concentration waste water retaining behind the membrane, hasn’tbeen solved effectively. In this study, by analyzing the MBR effluent leachate, the researcherdecided to use the two-stage Fenton-BAF treatment to treat the leachate, take the place of theoriginal RO treatment and solve the problems above.In this study, the researcher used PFS (Polymeric Ferric Sulfate) coagulation and Fentontreatment as pretreatment to deal with the MBR effluent leachate, both of the pretreatmentsperformed well. Considering the·OH in Fenton treatment can convert the chemical structureof the refractory organic compounds, promote the effluent’s biodegradability, the studydecided to use Fenton treatment as the ideal pretreatment for the leachate. The optimumcondition of Fenton treatment is: initial pH=4, H2O2dosage is0.048mol/L, the molar ratio ofH2O2and Fe2+is2.5:1, on this condition, the removal ratio of COD, TOC, UV254and Chromais68.2%,61.5%,85.1%and92.2%respectively.To save the Fenton treatment chemical cost, the researcher adjusted some processes ofthe conventional Fenton treatment, put forward the concept of Modified Fenton treatment.The Modified Fenton save the chemical cost of H2SO4and NaOH, the total chemical cost isjust24%of the conventional one. Though the removal efficiency of Modified Fenton is lessefficiently than the conventional one (the removal ratio of COD, TOC, UV254and Chroma is54.8%,68.9%,69.8%and71.9%respectively), as a new pretreatment, it still has certainapplication potential.The researcher used GC-MS and Fluorescence technology to analyze two-stageFenton-BAF’s effluent from each treatment unit, verify the organic compounds, especially therefractory ones’ conversion process. The result verified that Fenton oxidation can destroy the organic compounds’ steady structure (like aromatic ring and conjugated bond), modify somecertain functional group (like adding carbonyl, hydroxyl.etc), convert the macromoleculecompounds into smaller ones. The oxidation process can promote the effluent’sbiodegradability.