The use of analytical techniques for the characterization of natural organic matter (NOM) and the assessment of NOM's transformations, interactions, and removal during drinking water treatment

This work sought to broaden the water treatment industry's knowledge about natural organic matter (NOM) character and its relationship to water treatment. The following American Water Works Service Company and Aquarion Water Company water treatment plants were sampled: The Delaware River Regional Water Treatment Plant (WTP) (Delran, NJ), Philipsburg WTP (Philipsburg, PA), Dean's Mill WTP (Mystic, CT), Jumping Brook WTP (Shrewsbury, NJ), and Hopewell WTP (Hopewell, VA). At each of the plants, the NOM in the effluents of each major treatment process was qualitatively and quantitatively characterized using tetramethylammonium hydroxide (TMAH)-thermochemolysis gas chromatography (GC) with mass spectrometry (MS) (TMAH GC-MS).; The results indicated the following: (1) despite differences in location, the NOM entering the plants was similar; (2) 36 compounds were quantified in the samples (representing 0.07--2.7% of the total organic carbon present) consisting of aromatics of uncertain origin, fatty acids (detected as fatty acid methyl esters), and p-hydroxyphenyl, guaiacyl, and syringyl lignin-derived aromatics; (3) after ozonation, the concentration of a few fatty acids and aromatic compounds increased to 1.2 to 9.7 times their influent concentrations; (4) superpulsator(TM) clarification decreased the quantified NOM by 57%; (5) after biological granular activated carbon (GAC) filtration, the concentration of a few aromatics and fatty acids increased by 1.1 to 7 times their superpulsator(TM) effluent concentrations; and (6) aromatics with only hydroxyl substituents were not removed as well as aromatics with carboxyl, ketone, and aldehyde substituents.; In terms of water treatment: (1) ozonation transformed NOM; (2) coagulation/settling decreased NOM concentrations by 7--68%, especially aromatics and long chain fatty acids; (3) bio-GAC filtration removed NOM very well (by 46--78%), especially when the filter was in operation for less time and was operating primarily under adsorption conditions with some bioactivity; (4) a bio-GAC filter operating for almost 3 years was still adept at lowering the concentration of aromatic NOM by 2.5%; probably due to the biological degradation of NOM; and (5) water utilities that removed the dominant fraction of quantified NOM entering their plants achieved higher NOM removals (69--91%). These findings provide a greater understanding of NOM character, removal, and transformations during water treatment.