AWWA ACE94143

A fraction of heterotrophic bacteria that survives inactivation by significant free chlorine residuals for at least 120 minutes persists in both settled and biofiltered samples. Factors promoting this survival are ubiquitous and able to break through very restrictive physical barriers (microfiltration) in both in situ and pure culture samples. Biofilters did not diminish the biocidal efficacy of free chlorine or contribute to tailing observed in bacterial survival curves. The fraction of bacteria that survived chlorination actually appeared to be reduced in biofiltered samples. This study suggests that a significant fraction of heterotrophic bacteria that survives chlorination in free suspension may be imported from surface water and pass through a treatment facility into a distribution system where they may survive for an extended period of time. Further studies are recommended to determine: if this surviving fraction promotes biofilm formation; and to what extent bacterial pathogens may be protected when associated with this surviving fraction.

Product Details

Published:

01/01/1994

ISBN(s):

0898677742

Number of Pages:

10

File Size:

1 file , 320 KB