Ct values required for degradation of microcystin-LR by free chlorine

Xagoraraki, Irene; Zulliger, Kimberly; Harrington, Gregory W.; Zeier, Benjamin; Krick, William; Karner, Dawn A.

doi:10.2166/aqua.2006.0008

Cited by 5 publications

(1 citation statement)

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“…In general, the degrada tion of microcystin increased with increasing ct. This has been observed previously although typically in the absence of NOM, suggesting that the decay of chlorine can effectively be ignored ( , ). Under these conditions a pseudo first-order rate law (eq 3) adequately describes the degradation of toxin at a given pH where ct = the chlorine exposure; [tox] ct = the residual toxin concentration after exposure to chlorine; [tox] 0 = the initial toxin concentration; and k app = the apparent rate constant.…”

Section: Resultssupporting

confidence: 70%

Effect of Chlorination on Microcystis aeruginosa Cell Integrity and Subsequent Microcystin Release and Degradation

Daly

Brookes

2007

Environ. Sci. Technol.

268

128

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The proliferation of cyanobacteria in drinking water sources is problematic for water authorities as they can interfere with water treatment processes. Studies have shown that oxidants such as chlorine can enhance the coagulation of cyanobacteria; however, chlorine can potentially lyse cyanobacterial cells, releasing toxic metabolites. Chlorine also has the potential to effectively degrade these toxins. This study evaluated the effect of chlorine on the cell integrity of toxic Microcystis aeruginosa in reservoir water using flow cytometry. In addition, the effect of chlorine on the subsequent release and degradation of microcystin toxins was systematically assessed. Cell lysis occurred at chlorine exposure values between 7 and 29 mg min/L, which is within the range of normal disinfection practices. Intracellular toxin was shown to be released from damaged cells at a rate three times faster than it was degraded by chlorine. The degradation of extracellular microcystin by chlorine was found to be dependent upon the pH, chlorine exposure, and the presence of cyanobacterial cells.

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