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Water Treatment Plant Section #2
Since the hardness of the lake water varies from 100 mg/l (soft) in the summer to 400 mg/l (very hard) in the winter, the Camrose water has to be softened. Camrose water is softened to approximately 120 mg/l year round. The softening process has the added benefit of removing more of the color, taste, and odor.
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The second clarifier is used to soften the water. This is done by adding lime, which bonds with the calcium and magnesium in the water and then settles to the bottom of the clarification tank forming a thick sludge made up of calcium carbonate and magnesium carbonate. A rake pushes this sludge to the center of the tank where it is removed and pumped to the centrifuge. A centrifuge removes most of the water from the sludge, turning it into a thick chalk-like paste, that is then transported to the landfill. The clear softened water rises to the top of the clarifier where it is collected and piped to the "floc" chambers. |
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The softening process increases the pH level of the water from approximately 8.3 to 12. If the water were left at pH12 it would leave deposits on the pipes in the distribution system and eventually plug them. The pH must be lowered to 8.3 which is the level at which the water is neither corrosive (dissolving pipes) nor aggressive (forming scales). Bubbling carbon dioxide gas through the water lowers the pH level. |
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After a pH adjustment, the water is filtered. Camrose employs a tri-media, constant rate filter system. This is a natural sand filter system consisting of several layers of gravel, sand and anthracite. The water moves through a layer of anthracite, then successively coarser sand and gravel. The filter system, which is backwashed regularly to prevent blockage, removes any of the remaining particles from the water. (Filter Schematic) |
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In April of 2001, an ultraviolet(UV) system was integrated into the treatment process. The UV system was installed provide an additional treatment barrier, specifically targeting the inactivation of pathogenic organisms such as Giardia lamblia (Giardia) and Cryptosporidium parvum (Crypto). |
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Finally, chloramine is added to the water. Chloramine is a combination of chlorine and ammonia. It is a very stable and effective disinfectant. A minimum of 0.5 parts/million of chlorimine must be maintained in the distribution system to protect against contamination and infections such as E-coli. |
Fluoride occurs naturally in our water at approximately 0.3 parts per million. Since a referendum in 1986, the City of Camrose has added fluoride to the water leaving the water treatment plant to bring the total fluoride level to 0.8 parts per million. Fluoride reduces tooth decay, particularly in young children.
The City of Camrose is currently undergoing some upgrades to the Water Treatment Plant, with the addition of a Granular Activated Carbon (GAC) contact facility. The addition of the GAC facility will result in a higher removal of organic carbon and other contaminants from the water, which will result in better disinfection of the water. As well, the GAC system should also reduce the occurrences of high odour and taste problems which we periodically experience. The City hopes to have the new GAC system in operation by late 2007 or early 2008.
