Removal of Algal Toxins by Potassium Permanganate: Incorporating Competition from Natural Water Constituents
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Date
2018-03
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Abstract
In recent years, the increased occurrence and severity of harmful algal blooms has threatened public health. These blooms are capable of producing a number of toxins including microcystins, cylindrospermopsin, and saxitoxin. These toxins can enter drinking water treatment plants and if not effectively removed, they pose a serious threat to human health. The work here investigated the efficacy of permanganate as a treatment strategy. We report rate constants of 272 ± 23 M-1 s-1 for the reaction between permanganate and microcystin-LR, 0.26 ± 0.05 M-1 s-1 for the reaction between permanganate and cylindrospermopsin, and estimate a maximum rate constant of 2.7 ± 0.2 M-1 s¬-1 for the reaction between permanganate and saxitoxin based on chemical analogs. We conclude that permanganate only shows potential to remove microcystins. No pH or alkalinity dependence on the rate of reaction between microcystin-LR and permanganate was observed; a temperature dependence, however, was observed and can be characterized by an activation energy of 16 ± 5 kJ mol-1. The competition posed by cyanobacterial cells was quantified by an apparent second order rate constant of 2.5 ± 0.3 x 10-6 L μg-chl-a-1 s-1. From this apparent second order rate constant, it was concluded that cyanobacterial cells are not efficient scavengers of permanganate. The competition posed by dissolved organic matter (DOM) was quantified by an apparent second order rate constant of 8.8 ± 3.1 x 10-5 L mg-C-1 s-1. Neither DOM source type nor electron donating capacity was observed to impact the rate of reaction between DOM and permanganate. DOM was concluded to efficiently scavenge permanganate and we forward that this should be considered in permanganate dosing calculations.
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Engineering: 3rd Place (The Ohio State University Edward F. Hayes Graduate Research Forum)
Keywords
permanganate, algal toxin, microcystin, drinking water, dissolved organic matter, cyanobacteria