AWWA WQTC60568

Gate valves with rubber-coated wedges were found to be the cause of coliform contaminations ofdrinking water without disinfectant residual. The characteristic organism was Citrobacter freundii,which was isolated from the drinking water as well as from the surface of the rubber-coated wedges.The rubber on the wedges was covered with excessive biofilms in which the coliform bacteria musthave multiplied after initial inoculation by contaminated water. Thus, one of the prerequisites forminimizing the potential of coliform proliferation was to reduce biofilm formation on the rubbersurface. This was achieved by developing new rubber types with strongly reduced proportions ofmicrobiologically degradable components.In drinking water distribution systems rubber materials with excessive biofilms provide a potentialhabitat for potentially pathogenic bacteria and have to be considered as a potential source ofcontamination in non-chlorinated drinking water. Includes 10 references, tables, figures.

Product Details

Edition:

Vol. - No.

Published:

11/15/2004

Number of Pages:

19

File Size:

1 file , 8.4 MB