title: Early warning of faecal contamination of water: a dual mode, automated system for high- (< 1 hour) and low-levels (6-11 hours).
abstract: There is a recognised need for methods that permit rapid estimation of the sanitary quality of water e.g. during raw water monitoring and emergencies involving water treatment failure or main breaks in a distribution network. In this study, two models for predicting the level of faecal contamination of water were studied. The first format, based on measurement of beta-galactosidase activity by the automated Colifast analyser, detected faecal contamination of high levels, corresponding to > 15 thermotolerant coliforms (FC)/5 mL, in 1-3 h, in a format that allowed for semi-quantification of results. By setting up a cut-off level, the system could be used as an operational tool identifying random increases in faecal contamination during routine raw water monitoring. A second Presence-Absence format was dependent upon the growth of low levels of FC with subsequent detection in the Colifast analyser. 95% of water samples containing 1-15 FC/sample volume showed positive detection after 11 h.
authors.affiliation: Colifast AS, PO Box 31, N-1324 Lysaker, Norway. ingun.tryland@colifast.no
authors.forename: I
authors.initials: I
authors.lastname: Tryland
authors.forename: I D
authors.initials: ID
authors.lastname: Samset
authors.forename: L
authors.initials: L
authors.lastname: Hermansen
authors.forename: J D
authors.initials: JD
authors.lastname: Berg
authors.forename: H
authors.initials: H
authors.lastname: Rydberg
mesh_terms: D001331:Automation; D001681:Biological Assay / Q000379:methods; D004755:Enterobacteriaceae / Q000302:isolation & purification*; D004784:Environmental Monitoring / Q000379:methods; D005243:Feces; D005696:Galactosidases / Q000032:analysis / Q000378:metabolism*; D008962:Models, Theoretical; D011157:Population Dynamics; D013696:Temperature; D018508:Water Purification; D014881:Water Supply
chemical_list: D005696:Galactosidases