Harmful algal blooms are a major concern worldwide and are especially problematic in the United States since algae can impact drinking water treatment plants that depend on surface water sources. During drinking water disinfection, natural organic matter and other constituents react with the disinfectant to produce disinfection by-products (DBPs). DBPs are of concern because they are linked to various human health effects, including bladder cancer, miscarriages, and birth defects. Harmful algal blooms produce toxins that, when present in drinking water sources, become potential precursors for DBPs. In this study, we investigate the formation of regulated and priority unregulated DBPs from the chlorination and chloramination of algae and source waters, specifically Lyngbya wollei, Microcystis aeruginosa, Phormidium sp., and Saxitoxin (algal toxin) to better understand DBP formation in algae-impacted drinking water. The impact of Br^- and I^- was also investigated. Chlorination and chloramination reactions were performed in the laboratory to mimic drinking water treatment conditions. Lyngbya wollei algae was collected from 3 drinking water reservoirs/lakes in SC, and Phormidium sp. was collected from a lake in SC. DBPs were measured from real finished drinking water and from controlled laboratory reactions of live algae and source waters by sensitive gas chromatography (GC)-mass spectrometry (MS) methods created in our laboratory. Liquid chromatography (LC)-high resolution-MS is also used to identify highly polar DBPs. Several classes of DBPs were observed during controlled laboratory reactions of algae and source waters including halomethanes, haloacetonitriles, haloacetamides, and haloacetic acids at higher levels. Higher µg/L levels of brominated and iodinated DBPs were formed from the same amount of algae when bromide and iodide ions were present. Total amount of DBPs formed was higher during chlorination than chloramination. Only 3 DBPs were observed during chlorination of Saxitoxin, and they were below quantification limits.

Samuel Putnam

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