Photocatalytic oxidation of DBP precursors using UV with suspended and fixed TiO2

French River water (Nova Scotia, Canada) was separated into six different natural organic matter (NOM) fractions, including hydrophobic acids, bases and neutrals and hydrophilic acids, bases and neutrals. The raw water, as well as each of the NOM fractions were analysed for disinfection by-product (DBP) formation potential before and after advanced oxidation with UV/TiO2 to determine the efficacy of this treatment for the removal of DBP precursors. The UV/TiO2 treatment was carried out with a nanostructured thin film (NSTF), coated with TiO2 which is compared with the use of a TiO2 suspension. For the raw river water, removals of total trihalomethane formation potential (TTHMFP) and total haloacetic acid formation potential (THAA9FP) were found to be approximately 20% and 90%, respectively, with 50 mJ/cm2 UV exposure and 1 mg/L TiO2. For the fractionated samples, approximately 75% of both trihalomethane (THM) and haloacetic acid (HAA) precursors were found to be associated with the hydrophobic acid fraction. For this individual fraction the same UV/TiO2 treatments exhibited approximately 20–25% removal of both TTHMFP and THAA9FP, suggesting that the fractionation process may have affected the treatability of HAA precursors or may have altered the results of the oxidation processes.

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► We measure disinfection by-product (DBP) formation potential of a surface water.
► Water is separated into NOM fractions; DBP formation potential is measured for each.
► Raw water and fractions are exposed to suspended and fixed UV/TiO2 treatments.
► Suspended UV/TiO2 treatment provided better removal of DBP precursors.
► UV/TiO2 treatment removed most haloacetic acid precursors and some trihalomethane precursors.