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Turbidity, Color, Odour & Taste

Treatment Methods-Equipment Application
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Let us look at the ways that these pieces of equipment may be used to treat the problems of turbidity, color, odor and taste.

If the problem is simply one of suspended solids or turbidity, with no evidence of color, odor or taste, one of the mechanical filters may be used to remove the solid particles. Depending on the specific circumstances, a large tank-type unit may be used to filter the entire water supply after the water leaves the pressure tank. If the turbidity is of such a nature that complete removal is not achieved, a cartridge filter might be used in the water line to a specific tap. Alternately, if the turbidity is not a major problem, and really is objectionable only in water used for cooking and drinking, the cartridge filter may be used on specific taps and the tank-type unit may not be necessary.

Similar approaches may be used with activated carbon filters. The large tank-type units may be used to remove turbidity and many tastes and odors from the entire water supply, or the cartridge filters may be used in individual water lines.

If the load of organic matter is very high, and the activated carbon becomes saturated rapidly, chlorine can be used to oxidize the organic matter. A chemical feed pump can be wired to operate with the well pump, and a solution of household hypochlorite bleach fed into the water line between the pump and the pressure tank. The pressure tank serves as a mixing vessel and allows at least some time for the oxidation of the organic matter. In some unusual case, it is necessary to install extra tanks for more contact time when the organic matter resists oxidation. The chemical feed is adjusted to provide a chlorine residual of 3 to 5 ppm after the tank(s).

Since this amount of chlorine would be objectionable for cooking and drinking, and the water could contain any precipitated iron or other materials, an activated carbon filter may be used in the water line to remove both the precipitated matter and the excess chlorine. Treating the water by filtration and chlorination has the advantage of removing iron as well as disinfecting the water.

Hydrogen sulfide in the water is a special case, as noted above. At very low concentrations, an activated carbon filter may be used, and occasional treatment with bleach will extend the life of the carbon. For low to moderate "sulfur" concentrations, an iron removal filter may be effective in correcting the problem. For higher concentrations, the chlorination system with activated carbon filtration is the best solution for hydrogen sulfide removal.

In all of these cases, the equipment should be installed ahead of a water softener, if one is used, to protect the softener against fouling, and also to permit the use of unsoftened water in some water lines.

Finally, if the taste is due to high concentrations of dissolved materials, the small reverse osmosis units are recommended. Since these units too are subject to fouling if the water contains organic matter, turbidity, iron, and similar contaminants, pre-filtration is often recommended. If a water softener is used for hardness removal, the softened water should be fed to the reverse osmosis unit to improve the mineral removal performance and extend the life of the membrane.

IMPORTANT: The determination of which treatment method is best should be made only after careful consideration of many factors such as economics, water quality characteristics, the end use to which the water is to be put, temperature variances of the water to be treated, the inherent limitations of the available treatment technology, and others. This determination can best be made by your local water treatment representatives and they should be consulted prior to the purchase and installation of any water treatment equipment.

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