Citation:

Dugan, N., S. Smith, AND T. Sanan. The Impacts of Potassium Permanganate and Powdered Activated Carbon on Cyanotoxin Release. Journal AWWA. American Water Works Association, Denver, CO, 110(11):E31-E42, (2018). https://doi.org/10.1002/awwa.1125

Impact/Purpose:

The purpose of the research described in this manuscript was to explore the impact of potassium permanganate and powdered activated carbon, applied early in the drinking water treatment process, on toxin release from cyanobacterial cells. It is anticipated that the results discussed in this manuscript will be of value to EPA regional personnel, state primacy agency personnel, drinking water utility personnel and consulting engineers.

Description:

The U.S. Environmental Protection Agency (USEPA) undertook a series of bench-scale trials with the following objectives: (1) Expose suspensions of Microcystis aeruginosa (M. aeruginosa) to potassium permanganate (KMnO4) doses of 1, 3 and 5 mg/L, at contact times of 15, 30 and 90 minutes, pH levels of 7 and 9, and turbidities of 0.1, 5 and 20 NTU; (2) Compare the impacts of oxidation alone and oxidant plus powdered activated carbon (PAC) for the final 60 minutes of contact time at all the previously described experimental conditions and (3) evaluate the impact of these treatment conditions on extracellular microcystins, extra- plus intracellular (combined) microcystins, cell membrane integrity and chlorophyll-a concentrations. Toxin releases from the cells were observed at both pH levels. The greatest toxin releases were observed at the lowest KMnO4 doses. The toxin releases were accompanied by relatively stable total cell counts, increases in the concentration of membrane compromised cells and decreases in the concentration of chlorophyll-a. The application of 10 mg/L PAC resulted in extracellular toxin concentrations that were markedly lower than those observed in oxidant-only situations.

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