Study On Formation Of Catalytic Ozonation/Disinfection By-Products By Dynamic Experiment

More and more concerns have been paid to the pollution of drinking water sources in recent years. The removal of organic pollutants from drinking water and the control of disinfection by-products (DBPs) have become a crucial problem. Among various technologies used for advanced treatment, catalytic ozonation has good application potentials for water purification. Specially, catalytic ozonation with metal oxides as catalyst is a new technique to improve the ozonation of organic pollutants in water.The FeOOH loaded zeolite and CeO₂ loaded Al₂O₃ were used as the main catalyst in this research. The filtered water from water treatment plant was added with KBr, and then used as the raw water for this research. O₃/FeOOH and O₃/CeO₂ were compared on the formation of ozonation by-products presented by formaldehyde, pyruvic acid, bromate and the control of THMsFP and HAA5FP. Influence effects were investigated and continuous operation was performed.Degradation of UV₂₅₄ and TOC by O₃/CeO₂ was more efficient in comparison to O₃/FeOOH in filtered water.The formaldehyde production was increased by O₃/CeO₂ compared to O₃ alone while the production of pyruvic acid and bromate was distinctly decreased. As compared with ozonation alone, after O₃/FeOOH oxidation, the production of formaldehyde and pyruvic acid were both increased. The concentration of ozone and Br- mainly affected the production of ozonation by-products. The post treatment as biological carbon filtration is needed to achieve a better water quality.The THMsFP and TCAAFP of filtered water with Br- was reduced after ozonation, while the DCAAFP increased. The DCAAFP and TCAAFP were reduced by O₃/FeOOH comparing to ozonation alone, but the removal of THMsFP had no obvious advantage compared with ozonation alone. The THMsFP was reduced by 43.4% after CeO₂ catalytic ozonation than that after ozonation alone, and the DCAAFP/TCAAFP was reduced by 60%. The variation of THMsFP,DCAAFP and TCAAFP production under different conditions were different with each other. In the test, THMsFP and DCAAFP/TCAAFP could be reduced by reducing the O₃ concentration and reaction time. Bromide concentration in the water caused changes for the DBP species and their distribution. However, the reduction of DBPs formation potential by O₃/CeO₂ was not reduced by the increase of bromide concentration.During the period of continuous operation, the formation of ozonation by-products and DBPs were similar to those conclusions in the above experiment. The adsorption saturation of CeO₂ resulted in the increscence of pyruvic acid and bromate concentration in the effluent.