Compliance with increasingly stringent regulations on water quality at the customer's
tap is one of the most important challenges for managers of small drinking water
utilities. Among the important challenges for managers of
small drinking water utilities are the necessity of simultaneously ensuring adequate
micro-organism inactivation in the plant and control in the distribution system and
minimizing the formation of disinfection byproducts potentially carcinogenic, such as
trihalomethanes (THMs). When surface waters are utilized as raw water and chlorine
is used as the principal disinfectant, such a challenge becomes considerable. In the
U.S., small water utilities using both surface or groundwater will have in the coming
months or years to comply with a number of new National Primary Drinking Water
Regulations such as the stage 1 of the Disinfectants/DBP rule (for residual
disinfectant, maximum DBP levels and required treatment for organic carbon
removal), the long term 1 Enhanced Surface Water Treatment Rule and the
Groundwater Rule. In Canada, the
federal government has elaborated guidelines for drinking water quality which are not
mandatory but that can be used by Provinces to promulgate regulations for utilities
within their territory. Before 2000, only two Canadian
Provinces, Alberta and Quebec had promulgated
mandatory regulations. Following the water contamination event in the small
community of Walkerton (Ontario) during the summer 2000, in which 7 people died
and more than 2,000 were sick, some other Canadian provinces (British Columbia,
Nova Scotia, Ontario) published regulations or updated the existing ones. To ensure
that water between the treatment plant and the extremities of a distribution system is
of an acceptable microbiological quality, regulations require that a number of
standards be met, including a low water turbidity. The rules also require an efficient
inactivation of virus, bacteria and more recently Giardia and Cryptosporidium during
the disinfection process (notably by ensuring an adequate CT vale) and the
maintenance of a minimum free residual chlorine, at the exit point of the chlorination
basin or throughout the distribution system. As an added complication, the presence
of high concentrations of natural organic matter (NOM) in raw waters makes
compliance with water quality regulations more difficult. NOM is
known as a precursor of THMs and a source of assimilable organic matter (AOM) for
bacterial growth. This paper discusses how small utilities in Quebec are meeting there requirements.
Includes 10 references, tables, figures.
| Edition : | Vol. - No. |
| File Size : | 1
file
, 310 KB |
| Note : | This product is unavailable in Ukraine, Russia, Belarus |
| Number of Pages : | 9 |
| Published : | 06/16/2002 |
