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The occurrence of taste and odor (T&O) compounds in drinking water can lead to public concern about quality when left unaddressed, therefore suitable treatment is needed. This study evaluated the treatability of 18 T&O compounds using chlorine, permanganate, and ozone in MilliQ and river water. Nine T&O compounds showed complete oxidation (>99% removal) in all water matrices by ozone. Most of the remaining T&O compounds were removed to >50% by ozone. Alkalinity, pH, and natural organic matter (NOM) had a significant impact on the decay of ozone. Chlorine and permanganate were ineffective (removal <30%) for 2-methylisoborneol (2-MIB), geosmin, hexanal, pyrazines, and haloanisoles. Although chlorine achieved complete removal for alkyl sulfides and indole, it was only partially effective for aldehydes and ketones. Permanganate was more effective than chlorine in oxidizing unsaturated aldehydes and ketones. Increased NOM and pH reduced oxidation effectiveness for chlorine, but not permanganate. [ABSTRACT FROM AUTHOR]

Taste and odor (T&O) compounds in source waters can enter drinking water utilities causing customer concerns about the water quality if not removed during treatment. While there has been extensive research on two common T&O compounds, 2‐methylisoborneol (2‐MIB) and geosmin, research on non‐MIB/geosmin compounds has been limited. This study evaluated the treatability of 16 non‐MIB/geosmin compounds, 2‐MIB, and geosmin using powdered activated carbon (PAC). Four types of PAC were tested: two bituminous‐based, one lignite‐based, and one wood‐based PAC. Among the 18 compounds, PAC was effective for 15 compounds with at least 90% removal with typical PAC dosing, but was not suitable for dimethyl disulfide, ethyl methyl dioxolane, and cis‐3‐hexenol. The bituminous‐based PACs showed greater removal with higher adsorption rates compared to the lignite‐ and wood‐based PACs. The adsorption behavior of T&O compounds varied based on their physical and chemical characteristics, for example, hydrophobicity, and nature of functional groups. [ABSTRACT FROM AUTHOR]

Zeta potential distributions of model waters containing silica, humic acid, and differing ionic composition were evaluated. These distributions showed that under high ionic strength and in the presence of divalent cations, positive colloids exist in suspension with neutral and negative colloids. Positive colloids do not form at lower ionic strength or when polyvalent cations are absent. The existence of the positive colloids in suspension with the negative colloids suggests that, while electrodynamically unstable, some stabilizing factor is preventing coagulation. This stabilizing factor is likely adsorbed humic acid causing steric hindrance. Further tests indicated that under the conditions that lead to the existence of positive colloids, removal of humic acid by ferric chloride coagulation is diminished as compared to coagulation in lower ionic strength water or water containing just sodium chloride as the ionic matrix. As positively calcium-humic complexes can increase fouling of desalting membranes through the formation of densely packed fouling layers, understanding the mechanisms of coagulation in high ionic strength waters is crucial to improving performance of desalination operations. [ABSTRACT FROM AUTHOR]