Studies on the survival of enterohemorrhagic and environmental Escherichia coli strains in wastewater and in activated sludges from dairy sewage treatment plants.
Survival of Escherichia coli O157:H7 strain isolated from milk in Poland and an environmental E. coli strain in wastewater from Garwolin and Łowicz dairies and in activated sludges from dairy sewage treatment plants as well as in dairy wastewater with activated sludges was examined. Environmental materials were contaminated with about 10(8) of target bacteria/ml of sample. The experiments were performed under temperature conditions typical of autumn-winter (6 degrees) and spring-summer (24 degrees C) seasons. It was found that the non-pathogenic E. coli strain survived longer in all media than the enterohemorrhagic serotype. E. coli O157:H7 bacteria were not detected (in direct plating method) in activated sludges after 21-28 days; in dairy wastewater as well as in wastewater with activated sludges after 21-25 days. These periods for environmental E. coli strain were 35-42 days (activated sludges), 25-28 days (wastewater with activated sludges). At higher temperature environmental E. coli were not detected in wastewater from Łowicz dairy sewage treatment plant after 25 days, but the bacteria were still present in wastewater from Garwolin dairy sewage tratment plant after 34 days. The obtained results show that the lack of environmental E. coli bacteria (as a indicator bacteria of fecal contamination) in dairy wastewater and in dairy wastewater with activated sludges could indicate the absence of pathogenic E. coli bacteria. Prolonged existence of the enterohemorrhagic serotype in activated sludges shows the need to treat activated sludges prior to the utilization of these materials as fertilizer.
Czajkowska
Danuta
D
Faculty of Chemistry, Division of Drugs Technology and Biotechnology, Warsaw University of Technology, Warsaw, Poland. dczajkowska@ch.pw.edu.pl
Boszczyk-Maleszak
Hanka
H
Sikorska
I Rena
IR
Sochaj
Agnieszka
A
D000818:Animals; D015169:Colony Count, Microbial; D003612:Dairying; D004926:Escherichia coli / Q000254:growth & development*; D019453:Escherichia coli O157 / Q000254:growth & development*; D005516:Food Microbiology; D006863:Hydrogen-Ion Concentration; D007220:Industrial Waste; D050296:Microbial Viability; D008892:Milk / Q000382:microbiology; D010101:Oxygen Consumption; D011044:Poland; D012722:Sewage / Q000382:microbiology*; D013696:Temperature; D013997:Time Factors; D014871:Water Microbiology
D007220:Industrial Waste; D012722:Sewage