Treatment Of High Salinity Organic Wastewater By Photocatalytic Oxidation Process

High salinity organic wastewater has high toxicity and complex composition.Even if the wastewater is pretreated to remove some organic compount,it is still difficult to degrade by the biological treatment because of the high salinity in the wastewater.Organic wastewater treatment by one of the photocatalytic oxidation reaction,UV/H2O2/Fe2+,was studied in this paper.Acetic acid and 2-chlorophenol was choosen as model pollutant,the effect of different treatment methods on the degradation of pollutant was studied.Acetic acid was more difficult to be oxidized than 2-chlorophenol.Effect of 2-chlorophenol degradation by UV/H2O2/Fe2+ was better than UV/H2O2 and Fenton process,and acetic acid can only be treated by the UV/H2O2/Fe2+ process.The effects of H2O2 dosage,Fe2+ initial concentration,pH,H2O2 dose method and temperature on TOC removal were investigated.When pH=3,reaction temperature was 60 ?,the dosage of H2O2 was at the theoretical dosage,initial concentration of Fe2+was 50 mg/L,H2O2 was dripped as uniform speed,and the dripping time is 90min,the TOC removal of acetic acid was 97%after 120 min.When pH=3,the reaction temperature was 60 °C,the dosage of H2O2 was at the theoretical dosage and dosaged by one time,initial concentration of Fe2+ was 75 mg/L,TOC removal of 2-chlorophenol was 87.5%after 120 min.When H2O2 was dripped as uniform speed,the efficiency of H2O2 was found to be significantly improved.Under the optimal reaction conditions,the effect of sodium chloride concentration on the removal rate of TOC in wastewater was investigated,and it turned out that UV/H2O2/Fe2+ process could be utilized to treat high salinity organic wastewater.In addition,the kinetics of acetic acid and 2-chlorophenol degradated by UV/H2O2/Fe2+ process was deduced.When the initial concentration of TOC was 2250 mg/L and the dropping speed of H2O2 was 18.8 mL/h,the degradation process of TOC followed pseudo zero order kinetics,and the kinetic constants of k0=23.91 mg/(L · min).The mechanism of the reaction showed that high[TOC]/[H2O2]ratio was helpful to improve the efficiency of H2O2.The result of 2-chlorophenol wastewater degradated by UV/H2O2/Fe2+ process showed that within 30 min,the degradation process of TOC followed pseudo first order kinetics.The apparent rate constant k*was calculated under different temperature conditions and the apparent activation energy of the wastewater mineralization was turned out to be 14.43 KJ/mol.The apparent pre-exponential factor A was 8.383 min-1.Finally,the UV/H2O2/Fe2+ process was used to treat two kinds of wastewater.Based on the experimental results,a new wastewater treatment scheme was proposed.Experimental results show that the treatment effect of wastewater UV/H2O2/Fe2+reaction,could be utilized as a pretreatment method to combine with other process,and it could also be used as the main method of wastewater treatment to remove the organic matter in wastewater.