Title

Effect of Oxidant Demand on the Release and Degradation of Microcystin-LR from Microcystis Aeruginosa during Oxidation

Abstract

In this research, the release and degradation of intracellular microcystin-LR (MC-LR) due to oxidation of Microcystis aeruginosa (M. aeruginosa) was examined kinetically. Brief exposure to free chlorine with no measureable oxidant exposure was demonstrated to be sufficient to induce rapid release of intracellular MC-LR from M. aeruginosa. Thus, in a water treatment plant, there is currently no level of prechlorination that can be assumed to be safe, since very low preoxidation prior to filtration and no measureable free chlorine residual may still observe the release and buildup of extracellular MC-LR. Higher chlorine dosages resulting in a measureable exposure or CT (concentration times contact time) cause more rapid release and oxidation of the intracellular toxins. Further, the rate of release of MC-LR with intermediate oxidant dosages were shown to be initially rapid, but then slowed to a lower release rate due to an as yet undetermined mechanism. While free chlorine was reactive with the extracellular MC-LR, the monochloramine resulting from the consumption of the free chlorine by ammonia was not. Consideration of the ammonia concentration and the chlorine dosage relative to the chlorination breakpoint dosages is important for utilities assessing the impact of prechlorination of water containing cyanobacteria. MC-LR, once released, was rapidly oxidized by permanganate resulting in only negligible buildup of extracellular toxins.

Department(s)

Civil, Architectural and Environmental Engineering

Second Department

Chemistry

Comments

The authors acknowledge the Missouri Department of Natural Resources (Grant number 0045667) for funding this study.

Keywords and Phrases

Cell lysis; Chlorination; Microcystin-LR; Microcystis aeruginosa; Permanganate; Toxin release rate

International Standard Serial Number (ISSN)

0045-6535

Document Type

Article - Journal

Document Version

Citation

File Type

text

Language(s)

English

Rights

© 2017 Elsevier Ltd, All rights reserved.

PubMed ID

28463731

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