The Treatment Of Reverse Osmosis Concentrate Landfill Leachate By Fenton-BAF Process

With the disposal and discharge of landfill leachate put forward higher requirements in our country,in order to meet emission standards,the combination of biochemical method and membrane technology has been widely used in the treatment of landfill leachate.The resulting membrane filtration concentrate has high organic pollutants,large chromaticity,low biodegradation and strong toxicity,and can cause more serious environmental problems without proper treatment.In this thesis,the landfill leachate reverse osmosis concentrated solution produced by Guilin municipal solid waste treatment station was taken as the research object.Fenton oxidation combined with biological aerobic filter?BAF?combined process was used to treat the concentrated solution,and exploring its feasibility.The optimum process conditions of Fenton advanced oxidation process were studied to reduce the toxicity of the concentrate,improve the biodegradability of the concentrate and provide good conditions for subsequent BAF biological treatment.Though orthogonal analysis experiments,the Fenton reagent optimum experimental condition was determined for removing COD and NH₃-N in the concentrated.Taken the experimental efficiency and cost into consideration,the optimal technological parameters of Fenton reagent pretreatment of landfill leachate membrane filtration concentrate were as follows:H₂O₂/FeSO₄·7H₂O mole ratio were found be 4,H₂O₂ concentration was 34mL/L,The optimum pH was 5,and reaction time was 60min.In single factor experiment,the optimum process conditions were obtained by studying the Fenton oxidation method for treating landfill leachate membrane filtration concentrate at different initial pH,H₂O₂ dosage,n?H₂O₂?:n(Fe²⁺)and reaction time,Under the conditions of n?H₂O₂?:n?FeSO₄·7H₂O?=6:1,H₂O₂ dosage=30mL/L,initial pH=5,reaction time=60min,the removal rates of COD,UV₂₅₄ and chromaticity of membrane filtration concentrate were 74.25%?76.43%and 85.4%,respectively,BOD₅/COD increased from 0.014 to 0.31,and the biodegradability was significantly improved.The influencing factors on the Fenton's oxidating process of concentrated landfill leathate of reverse osmosis?RO?were investigated and analyzed by using response surface analysis method,taking the COD removal efficiency as the response value.The optimum pH,H₂O₂ concentration,H₂O₂/FeSO₄·7H₂O mole ratio were found be 4.94,1.0032mol/L,and 5.38 respectively and the highest COD removal efficiency?72.16%?could be achieved.The experimental values agreed well with the predicted values of the model equation,which can be used to confirm the treatment of concentrated landfill leathate of reverse osmosis by the Fenton method.The further degradation of Fenton-treated concentrated solution by BAF reactor was studied,the combined process had better removal effect on organic matters in the concentrated solution.The experimental results show that under the conditions of influent flow rate of 0.25L/h⁰.3L/h,gas-water ratio of 4:1⁶:1 and influent pH of 6.8⁷.5,the concentration of Fenton in influent is gradually increased,and the average removal rates of COD,NH3-N and TN are 55%,75%and 70%,respectively.Through UV-vis absorption spectrum and three-dimensional fluorescence spectrum analysis,the concentrated solution contains a large number of fulvic acid and humic acid.After treatment by Fenton-BAF combination process,the substituent on the aromatic ring is mainly fatty chain,and the content of aromatic organic compounds and humic acid macromolecular substances in the concentrated solution shows a decreasing trend,which indicated that the complexity of the organic compounds difficult to degrade in the effluent of the combined process was generally reduced,and had a good removal effect on humic acids and aromatic compounds.