Solid phase extraction as a simple method to measure and monitor trihalomethane precursors in surface waters
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Date
2019
Authors
Goss, Charles
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Abstract
This study investigated the isolation of hydrophobic (HPO) dissolved organic matter (DOM) using solid phase extraction (SPE) as an alternative method to the most commonly applied method using the XAD-8 resin. The objective being SPE is a simple method that could be suitable for monitoring seasonal changes in DOM composition and for evaluating water treatment performance by following the removal of trihalomethane (THM) precursors. This research was conducted in three phases.
In Phase I, seven SPE cartridges: Bond Elute ENV (ENV), Bond Elute Plexa, Bond Elute PPL (PPL), Strata X, C18-E, C18-U, and Oasis HLB were tested against the XAD method for their ability to isolate HPO DOM. Quantitative and qualitative analyses were conducted to determine if the SPEs tested isolated a similar HPO fraction as the XAD method. The results from Phase I found the Strata X, ENV and PPL isolated an HPO fraction comparable to the XAD method. As a result, these three SPEs were considered applicable for field testing of natural surface waters.
Phase II measured the HPO character in three surface waters: Lake Winnipegosis, the Waterhen River and the La Salle River over a 13-month period using ENV, PPL and Strata X. The results found all three SPEs isolated an HPO fraction; however, the Strata X isolated more DOM compared to ENV and PPL. FTIR results indicated that Strata X, and to some extent PPL, isolated some hydrophilic DOM. Phase II measured the THM formation potential (THMFP) and Specific THM formation potential (STHMFP) of fractions isolated using ENV, PPL and Strata X. The results concluded the HPO fraction isolated by each SPE had greater THMFP and STHMFP than the HPI fraction.
Of the three SPE studied in Phase II, ENV was found to be the most appropriate for Phase III, onsite testing by water treatment operators. The results from Phase III indicated that ENV was suitable for monitoring by operators, and that valuable information was gained from monitoring the removal of THM precursors using ENV.
The objective of this research was attained, demonstrating the value of monitoring THM precursors onsite using SPE, particularly ENV.
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Keywords
Humic Matter, Trihalomethanes, Soild Phase Extraction