Photocatalytic oxidation of DBP precursors using UV with suspended and fixed TiO_2

摘要

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/TiO_2 to determine the efficacy of this treatment for the removal of DBP precursors. The UV/TiO_2 treatment was carried out with a nanostructured thin film (NSTF), coated with TiO_2 which is compared with the use of a TiO_2 suspension. For the raw river water, removals of total trihalomethane formation potential (TTHMFP) and total haloacetic acid formation potential (THAA_9FP) were found to be approximately 20% and 90%, respectively, with 50 mJ/cm~2 UV exposure and 1 mg/L TiO_2. 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/TiO_2 treatments exhibited approximately 20-25% removal of both TTHMFP and THAA_9FP, suggesting that the fractionation process may have affected the treatability of HAA precursors or may have altered the results of the oxidation processes.