Characterization of size fractionated dissolved organic matter from river water and wastewater effluent using preparative high performance size exclusion chromatography

Abstract

Structural and functional characterization of dissolved organic matter (DOM) is challenging due to its inherent heterogeneity and coherent complexity. Here, a relatively new method based on preparative high performance size exclusion chromatography using deionized water as mobile phase (recovery rate of total carbon mass >97%) was developed to fractionate DOM depending on molecular size and identify molecular weight (MW)-dependent DOM characteristics presumably associated with its potential for formation of complexes with inorganic species (i.e. metals and metalloids), membrane fouling and disinfection byproducts. Size fractionated DOM from different types of source (river water vs. wastewater effluent) provided similar patterns in water quality, fluorescence properties and biopolymer composition. This suggested that discharge of municipal wastewater had an impact on the river water. However, the propensity for complexation between each size fractionated DOM sample and various inorganic species was substantially different, due to the differences in fluorescence spectral properties and associated biopolymer composition. Among three distinct size fractionated DOM samples, the fraction with medium MW and the main biopolymers polyhydroxy aromatics exhibited a relatively higher potential for metal complexation and the normalized ratio of metals and metalloids to dissolved organic carbon (DOC) [metal/DOC (fraction i, i = I, II, III)] to [metal/DOC (fraction I)] than the other size fractionated DOMs. The results indicate that the biopolymer composition of DOM plays a critical role in its complexation with inorganic species.