Abstract: Removal of organic pollutants from raw water by a combined process of TiO2-photocatalytic ozonation and biologically activated carbon (TiO2/UV/O3-BAC) was investigated. The TiO2/UV/O3 process decomposed macromolecule organic compounds into small molecules and increased their biodegradability. Under the optimum conditions, the dissolved organic carbon (DOC) was removed by 46.5% in the TiO2/UV/O3-BAC process, but the DOC was removed by only 41.6% in the UV/O3-BAC process. Compared with the UV/O3-BAC process, the synergetic effect of the TiO2/UV/O3-BAC process was stronger. The TiO2/UV/O3-BAC process was effective in removing phthalate esters, and their removal ratio reached more than 94% but decreased with the increase in the length of the alkyl side chains and the alkyl branch chains. The TiO2/UV/O3-BAC process was also very effective in removing polybromobiphenyls, and their removal ratio reached more than 89% but decreased with the increase in substitutional bromine atoms except for 2,2′,5,5′-tetrabromobiphenyl, which could be completely removed.

Key words: titania, photocatalytic ozonation, biologically activated carbon, raw water, phthalate ester, polybromobiphenyl