Transformation of dissolved organic matter during ozonation: Effects on trihalomethane formation potential

Transformation of dissolved organic matter (DOM) during ozonation results i n a higher reduction in trihalomethane formation potential (THMFP) relative to dissolved organic carbon (DOC). This study was conducted to determine t he effect of DOM transformation after ozonation on THM formation and to elu cidate the difference in THMFP and DOC removal. Changes in DOC, THMFP, reac tivities of the hydrophilic and hydrophobic DOC, and phenolic-OH were deter mined to explain the difference in THMFP and DOC removal after ozonation. H igher reduction in THMFP (24-46%) relative to DOC (10-16%) was obtained and was attributed to the following: transformation of DOM From a more reactiv e hydrophobic DOC (mug THM produced per mg organic carbon) to a less reacti ve hydrophilic DOC and to the decrease in the reactivities of both the hydr ophobic and hydrophilic DOC after ozonation. The results also showed decrea se in phenolic-OH indicating the oxidation of some reactive sites like reso rcinol or meta-dihydroxy benzene ring structures, which are prone to chlori ne substitution, consequently decreasing. the reactivity of the organic car bon to form THM. These changes in DOM led to a significant decrease in THMF P with no remarkable removal in DOC. (C) 2001 Elsevisr Science Ltd. All rig hts reserved.