Isolation and fractionation of natural organic matter: evaluation of reverse osmosis performance and impact of fractionation parameters

Dissolved organic matter (DOM) from three surface waters was isolated using reverse osmosis (RO) and subsequently fractionated using resin adsorption chromatography (RAC). Efficacy of RO was evaluated by closing mass balances for dissolved organic carbon (DOC). RAC was evaluated by investigating the effect of column operational parameters (column capacity factor, k', and solute initial concentration, C0) on DOM fractionation and subsequent disinfection by-product formation. Efficacy of RO was dependent on both isolation conditions and source water characteristics. In general, RO more effectively isolated DOM in high specific ultraviolet absorbance (SUVA254) water than low SUVA254 water, and showed higher DOM recovery at ambient pH (approximately 7) than at low pH (approximately 4). The fractionation of the isolated DOM indicated that the relative amount of the hydrophobic fraction decreased with increasing k', thus affecting the overall distribution of DOM. However, the distribution of DOM fractions was not influenced by varying C0 up to 150 mg l(-1) at k' of 15. The effect of k' on the formation and speciation of trihalomethanes (THM) and haloacetic acids (HAA) was not significant up to k' of 30.