The variation of mass and disinfection by-product formation potential of dissolved organic matter fractions along a conventional surface water treatment plant

Abstract

Dissolved organic matter (DOM) influences many aspects of water treatment, including the formation of potentially harmful disinfection by-products (DBPs) when disinfectants are applied. DOM from a conventional surface water treatment plant (WTP) in Northern New Jersey was isolated and fractionated using resin adsorption chromatography into six different fractions. These fractions are operationally categorized as hydrophobic acid, hydrophobic neutral, hydrophobic base, hydrophilic acid, hydrophilic neutral and hydrophilic base. The hydrophilic acid fraction was found to be the most abundant fraction in the source water. The hydrophilic neutral, hydrophilic acid and hydrophobic acid fractions had the highest removal efficiency through the WTP (about 65%). The variation and removal effectiveness of each fraction along the WTP was studied. Seven-day chlorine DBP formation potential (FP) tests were performed on all DOM fractions through the WTP. For the source water studied, the hydrophilic acid fraction was found to be the most reactive precursor to the trihalomethane (THM) formation. The hydrophobic neutral fraction was found to be the fraction of concern with respect to the FP of haloacetic acids (HAAs) class of DBPs. The FP of each fraction's class of DBPs was found to be amenable for reduction along the treatment train, specifically by coagulation/sedimentation. The fractionated approach concept showed to be very beneficial in the study of DBP precursors and their effective removal by physical and chemical treatment.