title: Disinfection of bacteria in water systems by using electrolytically generated copper:silver and reduced levels of free chlorine.
abstract: As an alternative disinfectant to chlorination, electrolytically generated copper:silver (400 and 40 micrograms/L copper and silver, respectively) with and without free chlorine (0.3 mg/L) was evaluated over a period of 4 weeks in indoor and outdoor water systems (100 L tap water with natural body flora and urine). Numbers of total coliform, pseudomonas, and staphylococci were all less than drinking water standards in systems treated with copper:silver and free chlorine and systems treated with free chlorine alone (1.0 mg/L). No significant differences (p less than or equal to 0.05) in bacterial numbers were observed between systems with copper:silver and free chlorine and those with free chlorine alone. Overall, free-chlorine treatments (0.3 or 1.0 mg/L) showed significantly lower heterotrophic plate numbers than those without free chlorine. When challenged with a natural Staphylococcus sp. isolate, water with copper:silver and free chlorine had a 2.4 log10 reduction in bacterial numbers within 2 min, while free chlorine alone or copper:silver alone showed 1.5 and 0.03 log10 reductions, respectively. Addition of copper:silver to water systems may allow the concentration of free chlorine to be reduced while still providing comparable sanitary quality of the water.
authors.affiliation: Department of Nutrition and Food Science, University of Arizona, Tucson 85721.
authors.forename: M T
authors.initials: MT
authors.lastname: Yahya
authors.forename: L K
authors.initials: LK
authors.lastname: Landeen
authors.forename: M C
authors.initials: MC
authors.lastname: Messina
authors.forename: S M
authors.initials: SM
authors.lastname: Kutz
authors.forename: R
authors.initials: R
authors.lastname: Schulze
authors.forename: C P
authors.initials: CP
authors.lastname: Gerba
mesh_terms: D001419:Bacteria / Q000254:growth & development / Q000302:isolation & purification; D002713:Chlorine / Q000032:analysis; D015169:Colony Count, Microbial; D003300:Copper / Q000032:analysis; D004203:Disinfection; D004755:Enterobacteriaceae / Q000254:growth & development / Q000302:isolation & purification; D011549:Pseudomonas / Q000254:growth & development / Q000302:isolation & purification; D012834:Silver / Q000032:analysis; D013210:Staphylococcus / Q000254:growth & development / Q000302:isolation & purification; D013242:Sterilization; D013551:Swimming Pools; D014871:Water Microbiology
chemical_list: D012834:Silver; D002713:Chlorine; D003300:Copper