Submitted to: Journal of Water Supply: Research and Technology (AQUA)
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/25/2005
Publication Date: 12/1/2005
Citation: Chow, A.T., Gao, S., Dahlgren, R.A. 2005. Physical and chemical fractionation of dissolved organic matter and trihalomethane precursors: A Review. Journal of Water Supply: Research and Technology (AQUA) 54:475-507. Interpretive Summary: Difficulties persist in identifying reactive organic carbon in natural waters that form health hazardous compounds (e.g., trihalomethanes, THMs) during water treatment processes (e.g., chlorination). This paper reviews the principles of commonly used fractionation techniques, current state of knowledge, research advancement and gaps in organic carbon research. This review provides information that is useful for research scientists and industrial water suppliers to advance research and improve water quality.
Technical Abstract: High levels of dissolved organic matter (DOM) and its potential to form disinfection by-products (DBPs), such as trihalomethanes (THMs), during drinking water treatment raise challenges to management of source waters worldwide. Not all DOM is equally reactive in DBP formation during water disinfection and various physical and chemical fractionation techniques have been applied to identify the major reactive DBP components in DOM. In this review paper, we evaluate three commonly used fractionation techniques used in THM precursor research: XAD fractionation, ultrafiltration, and size exclusion chromatography. Research findings from different source waters worldwide are summarized in order to understand the role of various DOM fractions in THM formation and to identify knowledge gaps. The hydrophobic fraction and the fraction with an apparent molecular weight of 1k - 10k Daltons have been implicated as the primary source of THM precursors, but exceptions have been observed. Differences in isolation procedures, chlorination methodologies, origins of DOM, and nomenclature used to describe DOM fractions may contribute to discrepancies in results among some studies. Advancement of fractionation techniques in conjunction with sensitive spectroscopic techniques (e.g. UV absorbance and fluorescence) is essential for effectively evaluating DOM quality and quantity in source waters and optimizing water treatment processes.