Study Of The Landfill Leachate Membrane Concentrates Treatment Method

A large amount of refractory organic pollutants exist in leachate membrane concentrates,which are the main bottlenecks of popularization of membrane treatment for landfill leachate.Considering the individual advantages of coagulation,Fenton,electrochemical oxidation process and adsorption,this study focuses on the treatment performance of the combination of these methods for leachate membrane concentrates.First,Shaoxing and Changzhou landfills,which apply membrane method to treat leachate,were chosen for the water quality investigations.The leachate membrane concentrates of Changzhou was selected for seasonal water quality investigations.It was found that the highest COD and TOC concentration could achieve 5566 mg/L and 2630 mg/L,which were the keys of the following treatment.Secondly,the leachate membrane concentrates of Changzhou was selected as a research object for coagulation pretreatment.It was found that the performance of ferric coagulants were better than ferrous and PAC-like coagulants.The highest COD,TOC and chromaticity removal efficiencies could achieve 82%,81%and 97%when pH 4,FeCl3 5 g/L and PAM 0.07 g/L.Considering the cost and COD removal efficiency,the best coagulation conditions were:pH 4,FeCl3 3 g/L and PAM 0.07 g/L.Thirdly,the coagulaion effluent was treated by Fenton.The highest TOC,COD and chromaticity removal efficiencies could achieve 68.9%,69.6%and 100%when pH 2,H2O2 1 mol/L and Fe2+ 17.5 mmol/L,the COD concentration decreased from 1120 mg/L to 340 mg/L,and the main compound of removed contaminants were humic acids;H2O2 was the main factor of Fenton that affeacting the TOC removal efficiency.In the proper range of pH,the TOC removal efficiency increased with the increase of H2O2 and Fe2+ concentration.Adding Fenton reagents slowly and contiously could improve the H2O2 utilization efficiency,thus improving the TOC removal efficiency through slowing down the heat loss.Lastly,the Fenton effluent was treated by electrochemical oxidation process.It was found that when oxygen evolution electrode and titanium electrode were selected as anode and cathode electrodes,controlling pH to 6 all through the experiment,and electric intensity was 4V/cm,the COD concentration could decrease from 340 mg/L to 152 mg/L;The TOC removal efficiencies of pH controlled all through the experiment was better than those of pH adjusted in the beginning.And the electrochemical oxidation reaction matched more closely with pseudo-first-order kinetics equation;under the adsorption conditions of activated carbon(pH 4,activated carbon dosage 20 g/L,equilibrium time 1.5 h),the effluent COD concentration can meet the table 2 standard for Pollution Control on the Landfill Site of Municipal Solid Waste(GB16889-2008).During the adsorption process of activated carbon,sorption rate constant was 0.29/h,and the adsorption capacity was 2.84 mg COD/g.The combination of these methods in our study improve the effluent quality obviously,and the new potential of coagulation,Fenton and electrochemical oxidation process were found out.The effluent COD concentration can meet the table 2 standard for Pollution Control on the Landfill Site of Municipal Solid Waste(GB 16889-2008).Our finding results also could provide reference for industrial treatment of leachate membrane concentrates.