Effects of UV/PS and UV/H2O2 on Degradation of Natural Organic Matter and Formation Potential of Haloacetonitriles in Surface Water

This study aimed to investigate how degradation of organic matters in surface water by ultraviolet-activated persulfate (UV/PS) contributed to mitigation of formation of haloacetonitriles (HANs) comparing with conventional UV-activated hydrogen peroxide (UV/H 2 O 2 ). A surface water sample containing 10 mM of PS or H 2 O 2 was irradiated up to 3,000 mJ/cm 2 of 254 nm UV lump. Consequently, 3,000 mJ/cm 2 of UV/PS reduced formation potentials (FP) of dichloroacetonitrile (DCAN) and bromochloroacetnitrile (BCAN) from 3.8 to 0.2 µg/L and 2.8 to 0.6 µg/L, respectively. UV/H 2 O 2 also showed similar tendencies but reductions of DCAN and BCAN were less significant. However, both UV/PS and UV/H 2 O 2 were likely to increase FP of dibromoacetonitrile (DBAN). Additionally, correlation coefficient tests indicated that degradation of chromophore aromatic compounds and ful - vic acid-like substances by both UV/PS and UV/H 2 O 2 showed significant correlations with reduction of DCAN-FP. Degradation of some fluorophore aromatic proteins by UV/PS correlated to reduction of BCAN-FP, while increase of other portions of fluorophore aromatic proteins by UV/H 2 O 2 correlated to increase of DBAN-FP. Precursors of DCAN were easily decomposed by both treatments, whereas precursors of brominated HANs (BCAN and DBAN) were not preferentially attacked by them. However, strong oxidation potential of UV/PS achieved decomposition of these organic moieties.