title: Chemical disinfection of Legionella in hot water systems biofilm: a pilot-scale 1 study.
abstract: Legionella bacteria encounter optimum growing conditions in hot water systems and cooling towers. A pilot-scale 1 unit was built in order to study the biofilm disinfection. It consisted of two identical loops, one used as a control and the other as a 'Test Loop'. A combination of a bio-detergent and a biocide (hydrogen peroxide + peracetic acid) was applied in the Test Loop three times under the same conditions at 100 and 1,000 mg/L with a contact time of 24 and 3-6 hours, respectively. Each treatment test was preceded by a three week period of biofilm re-colonization. Initial concentrations of culturable Legionella into biofilm were close to 10(3) CFU/cm2. Results showed that culturable Legionella spp. in biofilm were no longer detectable three days following each treatment. evertheless, initial Legionella spp. concentrations were recovered 7 days after the treatments (in two cases). Before the tests, Legionella spp. and L. pneumophila PCR counts were both about 10(4) GU/cm2 in biofilm and they both decreased by 1 to 2 log units 72 hours after each treatment. The three tests had a good but transient efficiency on Legionella disinfection in biofilm.
authors.affiliation: Centre Scientifique et Technique du Bâtiment, 84 avenue Jean Jaurès, Champs-sur-Marne, 77447 Marne-la-Vallée cedex 02, France.
authors.forename: Maha
authors.initials: M
authors.lastname: Farhat
authors.forename: Marie-Cécile
authors.initials: MC
authors.lastname: Trouilhé
authors.forename: Christophe
authors.initials: C
authors.lastname: Forêt
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Hater
authors.forename: Marina
authors.initials: M
authors.lastname: Moletta-Denat
authors.forename: Enric
authors.initials: E
authors.lastname: Robine
authors.forename: Jacques
authors.initials: J
authors.lastname: Frère
mesh_terms: D018441:Biofilms; D004202:Disinfectants / Q000494:pharmacology*; D006358:Hot Temperature; D006861:Hydrogen Peroxide / Q000494:pharmacology*; D007875:Legionella / Q000187:drug effects*; D010463:Peracetic Acid / Q000494:pharmacology*; D010865:Pilot Projects; D016133:Polymerase Chain Reaction; D014871:Water Microbiology
chemical_list: D004202:Disinfectants; D006861:Hydrogen Peroxide; D010463:Peracetic Acid