The Coquitlam watershed treatment facility in British Columbia provides approximately 370 MLD, a third of the total water supply delivered in Metro Vancouver. The facility uses the process of ozonation as the primary disinfectant, but has added new UV disinfection equipment to complement the existing ozone and chlorination processes. Construction of the new facility started in spring 2011, and the technology cost under 100 million dollars to put in place.
Ultraviolet light at a wavelength of 254 nanometers passes through the water inactivating the micro organisms by disrupting the DNA of microorganisms preventing the organisms from reproducing. Since these organisms have a very short lifetime, without reproduction the population quickly dies away. UV radiation does not change the taste or color of the water.
The facility will continue to use ozone and chlorine as part of its multi barrier approach to disinfection. Each disinfection agent, ozone, UV and chlorine have their own unique advantages. Besides disinfection ozone can remove organic matter that can add color, taste or odor to the water. Ozone also can remove micro pollutants such as pesticides that may be present. UV is very effective against organisms that might require much higher doses of ozone or chlorine such as cryptosporidium. Chlorine provides a persistent residual in the water protecting the water distribution system from developing pathogens.
By employing all three approaches, Coquitlam is offering a significant layers of protection to the people of Vancouver.