Study On Treatment Of Petrochemical RO Concentrated Wastewater By Multiphase Catalytic /UV/Ozone Oxidation

The COD of petrochemical reverse osmosis-concentrate?RO?wastewater is only 100 mg/L,but because of the existence of aromatic series and organic acids with aliphatic chain in the wastewater,the advanced treatment of RO wastewater is one of puzzles in water treatment field.The photocatalytic oxidation tcchnology has a good effect on the treatment of wastewater,which is expected to solve the problem of degradation difficult on petrochemical RO concentrate wastewater.In order to decrease the COD below 50 mg/L,a reaction system of heterogeneous photocatalytic ozonation in fluidized bed is designed in this paper.The experiment is divided into two parts: the preliminary feasibility research on OR wastewater treatment using supported TiO₂ photocatalyst and the study of the effect of modified photocatalysttreating petrochemical RO concentrated wastewater.In order to meet the needs of fluidized bed photocatalytic oxidation reactor,a new kind of porous lightweight glass vector is developed,which is loaded by the nano titanium dioxide thin flim.Sol-gel method is used to synthesize the supported TiO₂ photocatalyst as well as modified photocatalyst mixed with six kinds of metal,using tetrabutyltitanate,absolute alcohol and glacial acetic acids as raw material,solvent and hydrolysis inhibitor,respectively.XRD and SEM-EDS is used to characterize the supported TiO₂ photocatalysts.The result shows that the crystal form of TiO₂ in unmodified photocatalyst is single anatase and average particle size is about 36 nm,while the particle size of modified one is obviously lager.The TiO₂ crystal form of MCAT-1?MCAT-2?MCAT-4?MCAT-5 and MCAT-6 photocatalyst are all single anatase phase,while TiO₂ exists in the form of anatase and rutile mixed crystals in the modified photocatalyst doped with Cu,which improves the catalytic performance ofphotocatalyst.The unmodified TiO₂ photocatalyst shows high catalytic performance in the experiment of H-acid degradation.But the performance of pertrochemical reverse osmosis-concentrate can't ment emission standards.The photocatalytic activity of Cu as doped metal achieve the best result among all kinds of supported TiO₂ photocatalysts,and the COD removal ratesuccessfully meets the emission standard.In this study,three kinds of reaction system are introduced :MCAT-3/UV/O₃ ?TiO₂/UV/O₃ and UV/O₃,among which MCAT-3/UV/O₃ system presents the best degradation effect.The optimal process parameters are as follows: pH=8;doping amount : 1%?mass fraction?;the dosage of photocatalyst : 10 g/L;oxidation time : 30 min.After treatment,the COD of effluent water is 20³5 mg/L.The result provides a technical reference for realizing industrialization of degrading petrochemical reverse osmosis-concentrate wastewater under the reaction system of heterogeneous photocatalytic ozonation in a fluidized bed.