AWWA ACE56181

The research project discussed herein, took a more detailed approach at discerning the character of natural organic matter (NOM) that existed in water from water treatment plants across the nation by employing the tetramethylammonium hydroxide (TMAH)-thermochemolysis technique, per a protocol developed by Patrick G. Hatcher and his research team. This technique is a step above pyrolysis GC-MS because it can readily analyze nonpolar and polar moieties of NOM. Tetramethylammonium hydroxide-thermochemolysis accomplishes this task by using TMAH to methylate compounds, thereby making them more volatile and amenable to chromatographic treatment. Thus, carboxylic acid groups transform to methyl esters, while hydroxyl groups transform to methyl ethers. For the purposes of the project, water was sampled from several water treatment plants of the American Water Works Company system, and two are focused on herein: the Delaware River Regional Water Treatment Plant of the New Jersey-American Water Company, and the Norristown Water Treatment Plant of the Pennsylvania-American Water Company. The treatment scheme consisted of ozonation; pretreatment with potassium permanganate, ferric chloride, lime, cationic polymer, and nonionic polymer; clarification with superpulsators; biological granular activated carbon filtration; and chlorination. The water sampling procedure consisted of collecting 20-liter samples in polycarbonate containers from the inlet of a water plant, before and after each treatment process, and from the plant effluent. The samples were preserved by freezing them immediately on-site before transporting them. Upon unthawing a sample at Penn State, total organic carbon analysis was completed on the unfiltered sample with a Shimadzu TOC analyzer, and 8-liters of the unfiltered sample was processed via vacuum evaporation at 35oC and 10-5 atm (Buchi Rotary evaporator). Subsequently, the sample was freeze-dried (Labconco freeze-dryer). Next, the TMAH-thermochemolysis protocol was performed on the sample at Ohio State. The TMAH protocol fragmented the natural organic compounds, and at hydroxyl or carboxyl sites, it replaced the hydrogen with a methyl group (CH3). This rendered the methylated products more discernable via the GC-MS protocol than they would otherwise be. Thus, the TMAH-thermochemolysis GC-MS procedure is well-suited for characterizing hydroxylated or carboxylated compounds. Includes 9 references, figures.

Product Details

Edition:

Vol. - No.

Published:

06/16/2002

Number of Pages:

21

File Size:

1 file , 690 KB