The occurrence of microbial contamination in drinking water distribution systems
can occur as a result of a system breech or as a result of microbial regrowth. Once in the
distribution system, cells attach to pipe walls to form a biofilm which can cause
biocorrosion of the pipes, noncompliance with drinking water guidelines, and undesirable
aesthetic changes in the drinking water. Other repercussions
associated with microbial activity in the distribution system include episodes of coliform
growth, an increased likelihood of waterborne disease, and an increased nitrate concentratio.
Secondary or residual disinfection is the process of applying a disinfectant that
provides a residual concentration in the distribution system. The three main disinfectants
used for secondary disinfection are chlorine, chloramines, and chlorine dioxide. Each of
these disinfectants have advantages and disadvantages, and the type of disinfectant used,
as well as the residual required, will depend upon the finished water quality and pipe
characteristics. At the same time, suppliers must minimize disinfection byproduct
formation, as well as control any unwanted taste and odour episodes that may be
associated with secondary disinfection.
In North America and some European countries, maintaining a disinfectant
residual in the distribution system has been used as a method of controlling biofilm
formation in the distribution system, and preventing microbial contamination in the
instance of a system breech. This has been done based on the premise that maintaining an
adequate disinfectant residual in the distribution system can minimize regrowth of
indicator or pathogenic microorganisms, detect microbial intrusion more rapidly than
microbial monitoring alone, and reduce the risk of general contamination as a result of a
distribution system breech. But what is considered an adequate residual?
The objective of this paper to provide an overview of secondary disinfectants, the
regulation in Canada and the US, and evaluate the physical and chemical factors that
affect the management of a disinfectant residual. Includes 18 references, figure.
| Edition : | Vol. - No. |
| File Size : | 1
file
, 250 KB |
| Note : | This product is unavailable in Ukraine, Russia, Belarus |
| Number of Pages : | 10 |
