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Natural Organic Matter

Treatment Processes
Fate and Transport
CAS Number:
Synonyms: AOC, BDOC, DOC, DOM, NOM, SUVA, TOC, assimilable organic carbon, biodegradable dissolved organic carbon, dissolved organic carbon, dissolved organic matter, fulvic acid, humic acid, specific ultraviolet absorbance, total organic carbon
Contaminant Type: Chemical

Natural organic matter (NOM) occurs in most natural water sources as a result of the decomposition of plant and animal residues through biotic and abiotic reactions [2446, 2467, 2470]. NOM consists of a variety of substances and chemical groups including humic acids, fulvic acids, carboxylic acids, phenols, aromatics, proteins, alcohols, aldehydes, ketones, esters, amines, hydroxy acids, amino acids, sugars, polysaccharides, and hydrocarbons [2470, 2471]. Fractions of NOM are often categorized according to their hydrophobicity and/or biodegradability [2454, 2470, 2471]. The amount of NOM and in a given water, and its characterization according to these categories, can vary with climate and season [2471].

NOM is commonly measured as total organic carbon (TOC) or dissolved organic carbon (DOC). Other measures, either of fractions of NOM or as indicators of NOM, include biodegradable organic carbon (BDOC), assimilable organic carbon (AOC), specific ultraviolet absorbance (SUVA), and formation potential for various disinfection byproducts (DBPs). Some studies also measure certain of the individual substances or chemical groups that can make up NOM (e.g., humic acids).

NOM is of concern in drinking water because it provides precursor materials for the formation of DBPs including trihalomethanes and haloacetic acids [2446, 2454, 2467, 2469, 2470, 2471]. Other impacts of NOM in drinking water include taste and odor, color, and increased chlorine demand in disinfection processes. NOM can also act as a carrier for toxic contaminants and contribute to bacterial regrowth and biofilm formation in distribution systems [2446, 2454, 2467, 2469, 2470].

Under the Stage 1 and Stage 2 Disinfection Byproducts Rules, the U.S. EPA requires monitoring for TOC as a measure of DBP precursors. It also requires drinking water systems using conventional treatment or softening to remove specific percentages of organic materials, measured as TOC. The percent removal requirements vary by source water TOC and alkalinity, ranging from 15.0 to 50.0 percent [2472].

Date of Literature Search: 2014

2446 Lohwacharin, J., Y. Yang, N. Watanabe, A. Phetrak, H. Sakai, M. Murakami, K. Oguma, and S. Takizawa; 2011; Characterization of DOM Removal by Full-Scale Biological Activated Carbon (BAC) Filters Having Different Ages; IWA Specialty Conference; N/A
2454 Tubic, Aleksandra; Jasmina Agbaba; Bozo Dalmacija; Jelena Molnar; Snezana Maletic; Malcolm Watson; and Svetlana Perovic; 2013; Insight into changes during coagulation in NOM reactivity for trihalomethanes and haloacetic acids formation; Journal of Environmental Management; Volume 118
2467 Wang, DS; YM Zhao; MQ Yan; and CWK Chow; 2013; Removal of DBP precursors in micro-polluted source waters: a comparative study on the enhanced coagulation behavior; Separation and Purification Technology; Volume 118
2469 Gibert, Oriol, Benoit Lefevre, Marc Fernandez, Xavier Bernat, Miquel Paraira, and Marc Pons; 2013; Fractionation and removal of dissolved organic carbon in a full-scale granular activated carbon filter used for drinking water production; Water Research; Volume 47, Issue 8
2470 Ghernaout, Djamel; 2013; The hydrophilic/hydrophobic ratio vs. dissolved organics removal by coagulation - A review; Journal of King Saud University - Science; http://dx.doi.org/10.1016/j.jksus.2013.09.005
2471 Matilainen, Anu and Mika Sillanpaa; 2010; Removal of natural organic matter from drinking water by advanced oxidation processes; Chemosphere; Volume 80, Issue 4
2472 U.S. EPA; 2010; Comprehensive Disinfectants and Disinfection Byproducts Rules (Stage 1 and Stage 2): Quick Reference Guide; Office of Water; EPA 816-F-10-080