Efficacy of a combined system of copper and silver and free chlorine for inactivation of Naegleria fowleri amoebas in water

J. M. Cassells, M. T. Yahya, C. P. Gerba, J. B. Rose

Research output: Contribution to journalArticle

23 Scopus citations

Abstract

Electrolytically generated copper and silver ions (400:40 and 800:80 µg/l) were evaluated, separately and combined with 1.0 mg/l free chlorine, for their efficacy in reducing the viable numbers of Naegleria fowleri amoebas in water (pH 7.3 and 23–25°;C). Inactivation rates (k = logl0 reduction/min) and T99 values (exposure time required to achieve a 99% or a 2 log10 reduction) of the disinfectants were determined. Copper and silver alone, at ratio of 400:40 to 800:80 µg/l caused no significant inactivation of N. fowleri even after 72 hours of exposure (k = 0.00017 and 0.000 13, respectively). Addition of 1.0 mg/l free chlorine to water which contained 400:40 or 800:80 µg/l copper and silver resulted in enhanced inactivation rates (k = 0.458 and 0.515, respectively) compared to either chlorine alone (k = 0.33) or the metals alone. Water containing 800:80 µg/l copper and silver with 1.0 mg/l chlorine showed a T99 value of 3.9 minutes, while chlorine alone showed a T99 of 6.1 minutes. Enhanced inactivation of N. fowleri by a combined system of free chlorine and copper and silver may be attributed to the different mechanism that each disinfectant utilizes in inactivating the amoebas, and may suggest a synergistic effect.

Original languageEnglish (US)
Pages (from-to)119-122
Number of pages4
JournalWater Science and Technology
Volume31
Issue number5-6
DOIs
StatePublished - Jan 1 1995

Keywords

  • Naegleria fowleri
  • amoebas
  • chlorine
  • copper
  • disinfection
  • inactivation
  • silver

ASJC Scopus subject areas

  • Environmental Engineering
  • Water Science and Technology

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