Study On Enhanced Electro-fenton Process For Treating Reverse-osmosis Concentrate Of Petro-chemical Waster

Reuse of wastewater with advanced technologies is an effective solution to water shortages in China.Reverse Osmosis(RO)has become the dominant desalination technology for wastewater reuse due to its good quality of water product and low cost of operation.However,RO systems will generate a significant amount of concentrate solution,which contains concentrated salt and biorefractory organic compounds.The efficient removal of refractory organic compounds in the high salinity system has become the main challenge for application of RO technology.In this paper,a new Electro-Fenton system for the treatment of RO concentrate was developed by combining the addition of hydrogen peroxide(H2O2)and the electro-generated H2O2 production via aeration.The main results and conclusions are as follows.1)This new electro-Fenton system can effectively degrade organic pollutants in petrochemical wastewater;aeration could effectively enhance the electro-Fenton process and significantly improve the removal of organics.The enhancement mechanism of aeration may be attribute to promoting Fenton reaction via electro-production of H2O2 at cathode,as well as improving the electro-coagulation process via oxidization of ferrous ion.The optimum conditions for treatment of RO concentrate were obtained as follows:H2O2 dosage of 150 mg/L,pH value of 4,current intensity of 10 mA/cm2,and air flux of 120 L/h.After reaction of 10 min,57.1%of CODC,was mineralized while CODCr removal reached 66.7%with 60 min reaction.2)The removal of organics in reverse osmosis concentrate of petrochemical wastewater can be significantly improved in DSA-enhanced electro-Fenton system.The optimum conditions were pH value of 4,current intensity of 30 mA/cm2,H2O2 dosage of 150 mg/L.After reaction of 60 min the removal of CODCr was up to 70.8%,and 63.3%of dissolved organic carbon(DOC)was degraded.3)The degradation behave of organics was investigated by using 3D-EEM and GC-MS measurement.The results showed that the fluorescent organic pollutants could be degraded by Electro-Fenton technology;both aeration and DSA anode could improve the degradation.The GC-MS results indicated that the pollutants in raw water included long-chain hydrocarbons,halogenated hydrocarbons,PAHs,esters,benzene series and organic acid.Halogenated hydrocarbons,PAHs and benzene series,can effectively degraded in the aeration-enhanced Electro-Fenton process,but few long-chain hydrocarbons was removed.DSA-enhanced process could perform well with the removal of long-chain hydrocarbons,as well as other priority pollutants.Both aeration and DSA enhanced Electro-Fenton could effectively treat the reverse osmosis concentrate of petrochemical wastewater,and is a promising technology for degradation of refractory organic compounds in high salinity system like RO concentrate.