Fenton-ECMR-BAF Integrated Process Development And Optimization For Nanofiltration Concentrate Processing

The effective treatment of landfill leachate is a key issue for urban development in the world.In the past decade,biological treatment followed by membrane separation technique such as membrane bioreactor(MBR),reverse osmosis(RO),nanofiltration(NF)have been widely applied and successfully commercialized in the treatment of landfill leachate.However,a kind of more refractory substance extracted from the membrane interception during NF and RO membrane process is produced and occupies as much as 13-30%of total incoming leachate in the form of concentrated leachate.The concentrated solutions contain high levels of refractory organic pollutants and inorganic salts,resulting in an increase on the treatment cost.Therefore,the great challenge is to develop an effective technology for the treatment of NF retentate from landfill leachate so as to meet the discharge requirements.In this paper,we propose a novel integrated process of Fenton-ECMR-BAF for the treatment of NF Retentate from landfill leachate.Firstly,MnOx/Ti electrocatalytic film was prepared by using sol-gel method to support MnOx catalyst with a flat titanium film as the substrate.Field-emission scanning electron microscopy(FESEM).X-ray diffraction(XRD).High-resolution transmission electron microscopy(HRTEM)and X-ray diffraction spectrometer(XPS)were employed to analyse the microstructure,crystal structure and electrochemical properties.The results show that MnOx is indeed supported on the surface of the titanium film and the electrochemical performance of the film is significantly improved.Firstly,the NF retentate is pretreated by Fenton process.The results showed that the COD removal rate was the highest when the initial pH was 3,molar ratio[H2O2]/[Fe2+]=2,and[H2O2]=180 mM,which reached 64.6%.A nano-MnOx loaded porous Ti membrane electrode was prepared via a sol-gel approach and employed as anode to constitute eight-stage ECMR for Fenton effluent treatment.The effects of operating voltage and residence time of ECMR on COD removal rate and energy consumption were investigated.Under the condition of operating voltage of 2.0 V and residence time of 10 min,the COD removal rate reached 21.3%,and the B/C value was increased from 0.05 to 0.38,which could be biochemically treated.During the BAF treatment,COD gradually decreased with the increase of residence time.After 48 hours of treatment,the COD of the effluent was reduced to 88 mg/L,and the chroma removal rate reached 99.5%.All the indicators reached the discharge standard.The results show that Fenton-ECMR-BAF integration process has successfully been developed for the treatment of NF retentate from landfill leachate.