title: On-line monitoring of Escherichia coli in raw water at Oset drinking water treatment plant, Oslo (Norway).
abstract: The fully automated Colifast ALARM™ has been used for two years for daily monitoring of the presence/absence of Escherichia coli in 100 mL raw water at Oset drinking water treatment plant in Oslo, Norway. The raw water is extracted from 35 m depth from the Lake Maridalsvannet. E. coli was detected in 18% of the daily samples. In general, most samples positive for E. coli were observed during the autumn turnover periods, but even in some samples taken during warm and dry days in July, with stable temperature stratification in the lake, E. coli was detected. The daily samples gave useful additional information compared with the weekly routine samples about the hygienic raw water quality and the hygienic barrier efficiency of the lake under different weather conditions and seasons. The winter 2013/2014 was much warmer than the winter 2012/2013. The monitoring supported the hypothesis that warmer winters with shorter periods with ice cover on lakes, which may be a consequence of climate changes, may reduce the hygienic barrier efficiency in deep lakes used as drinking water sources.
authors: Norwegian Institute for Water Research, Gaustadalléen 21, Oslo 0349, Norway. Ingun.Tryland@niva.no.|Norwegian University of Life Sciences, Ås 1432, Norway. Ingun.Tryland@niva.no.
authors: Ingun
authors: I
authors: Tryland
authors: Norwegian University of Life Sciences, Ås 1432, Norway. fasil.eregno@nmbu.no.
authors: Fasil Ejigu
authors: FE
authors: Eregno
authors: Colifast AS, Strandveien 33, Lysaker 1366, Norway. hb@colifast.no.
authors: Henrik
authors: H
authors: Braathen
authors: Colifast AS, Strandveien 33, Lysaker 1366, Norway. gk@colifast.no.
authors: Goran
authors: G
authors: Khalaf
authors: Oslo Water and Sewerage Works, Midtoddveien 40, Oslo 0494, Norway. ingrid.sjolander@vav.oslo.kommune.no.
authors: Ingrid
authors: I
authors: Sjølander
authors: Oslo Water and Sewerage Works, Midtoddveien 40, Oslo 0494, Norway. marie.fossum@vav.oslo.kommune.no.
authors: Marie
authors: M
authors: Fossum
mesh_terms: D057231:Climate Change; D060766:Drinking Water / Q000382:microbiology*; D004784:Environmental Monitoring / Q000379:methods*; D004926:Escherichia coli / Q000302:isolation & purification*; D020407:Internet; D060106:Lakes / Q000382:microbiology*; D009664:Norway; D012621:Seasons; D013696:Temperature; D014871:Water Microbiology; D018508:Water Purification; D014887:Weather
chemical_list: D060766:Drinking Water