The fate of natural organic matter during UV/H₂O₂ advanced oxidation of drinking water Available to Purchase

At conditions within the range of those typically applied for commercial drinking water applications, the impact of ultraviolet and hydrogen peroxide (UV/H₂O₂) advanced oxidation (AO) on the concentration, spectral characteristics, hydrophobicity, and biodegradability of natural organic matter (NOM) in a raw surface water and ultrafiltered surface water was studied. At an initial H₂O₂ dose of 20  mg L⁻¹, UV/H₂O₂ mineralized less than 15% of the NOM in raw surface water at a fluence of 1500  mJ cm⁻². Natural organic matter in ultrafiltered surface water was mineralized by at least 27% after about 1500  mJ cm⁻². Partial oxidation of NOM led to ring opening of aromatic structures, cleavage of conjugated double bonded carbon structures, and reduction in the degree of aromatic substitution. The UV/H₂O₂ AO preferentially reacted with hydrophobic fractions of NOM leading to the formation of hydrophilic products. The treatment oxidized recalcitrant NOM into more readily biodegradable compounds with significant increases in formaldehyde and acetaldehyde concentrations. Depending on NOM properties for a given water, UV/H₂O₂ AO may cause partial oxidation of NOM leading to the formation of biodegradable compounds. The presence of these species may need to be addressed with a downstream process capable of improving biological stability.