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| Physical Problems |
 TURBIDITY |
Source : Turbidity is the term given to anything that is suspended in a water supply. It is found in most surface waters, but usually doesn't exist in ground waters except in shallow wells and springs after heavy rains. Turbidity gives the water a cloudy appearance or shows up as dirty sediment. Undissolved materials such as sand, clay, silt or suspended iron contribute to turbidity. Turbidity can cause the staining of sinks and fixtures as well as the discoloring of fabrics. Usually turbidity is measured in NTUs (nephelometric turbidity units). Typical drinking water will have a turbidity level of 0 to 1 NTU. Turbidity can also be measured in ppm (parts per million) and it's size is measured in microns. Turbidity can be particles in the water consisting of finely divided solids, larger than molecules, but not visible by the naked eye; ranging in size from .001 to .150 mm (1 to 150 microns). The US EPA has established an MCL for turbidity to be 0.5 to 1.0 NTU, because it interferes with disinfection of the water. .
Treatment : Typically turbidity can be reduced to 75 microns with a cyclone separator, then reduced down to 20 micron with standard backwash able filter, however flow rates of 5 gpm/ sq. ft. are recommended maximum. Turbidity can be reduced to 10 micron with a multimedia filter while providing flow rates of 15 gpm/sq. ft. Cartridge filters of various sizes are also available down into the submicron range. Ultra filtration also reduces the turbidity levels of process water.
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| ODOR |
Source : Taste and odor problems of many different types can be encountered in drinking water. Troublesome compounds may result from biological growth or industrial activities. The tastes and odors may be produced in the water supply, in the water treatment plant from reactions with treatment chemicals, in the distribution system, and/or in the plumbing of consumers. Tastes and odors can be caused by mineral contaminants in the water, such as the "salty" taste of water when chlorides are 500 mg/l or above, or the "rotten egg" odor caused by hydrogen sulfide. Odor in the drinking water is usually caused by blue-green algae. Moderate concentrations of algae in the water can cause it to have a "grassy", "musty" or "spicy" odor. Large quantities can cause the water to have a"rotten", "septic", "fishy" or "medicinal" odor. Decaying vegetation is probably the most common cause for taste and odor in surface water supplies. In treated water supplies chlorine can react with organics and cause odor problems. Odor is listed in the Secondary Drinking Water Standards by the US EPA. The contaminant effects are strictly aesthetic and a suggested Threshold Odor Number (TON) of 3 is recommended.
Treatment : Odor can be removed by oxidation-reduction or by activated carbon adsorption. Aeration can be utilized if the contaminant is in the form of a gas, such as H2S (hydrogen sulfide). Chlorine is the most common oxidant used in water treatment, but is only partially effective on taste and odor. Potassium permanganate and oxygen are also only partially effective. Chloramines are not at all effective for the treatment of taste and odor. The most effective oxidizers for treating taste and odor, are chlorine dioxide and ozone. Activated Carbon has an excellent history of success in treating taste and odor problems. The life of the carbon depends on the presence of organics competing for sites and the concentration of the odor causing compound.
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| TASTE |
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Source : Generally, individuals have a more acute sense of smell than taste. Taste problems in water come from total dissolved solids (TDS) and the presence of such metals as iron, copper, manganese, or zinc. Magnesium chloride and magnesium bicarbonate are significant in terms of taste. Fluoride may also cause a distinct taste.
Taste and odor problems of many different types can be encountered in drinking water. Troublesome compounds may result from biological growth or industrial activities. The tastes and odors may be produced in the water supply, in the water treatment plant from reactions with treatment chemicals, in the distribution system, and /or in the plumbing of consumers. Tastes and odors can be caused by mineral contaminants in the water, such as the "salty" taste of water when chlorides are 500 mg/l or above. Decaying vegetation is probably the most common cause for taste and odor in surface water supplies. In treated water supplies chlorine can react with organics and cause taste and odor problems. See "ODOR" for more information.
Treatment : Taste and odor can be removed by oxidation-reduction or by activated carbon adsorption. Aeration can be utilized if the contaminant is in the form of a gas, such as H2S (hydrogen sulfide). Chlorine is the most common oxidant used in water treatment, but is only partially effective on taste and odor. Potassium permanganate and oxygen are also only partially effective. Chloramines are not at all effective for the treatment of taste and odor. The most effective oxidizers for treating taste and odor, are chlorine dioxide and ozone. Activated Carbon has an excellent history of success in treating taste and odor problems. The life of the carbon depends on the presence of organics competing for sites and the concentration of the taste and odor causing compound.
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| COLOR |
Source : Color in water is almost always due to organic material which is usually extracted from decaying vegetation. Color is common in surface water supplies, while it is virtually non-existent in spring water and deep wells. Color in water may also be the result of natural metallic ions (iron and manganese). A yellow tint to the water indicates that humic acids are present, referred to as "tannins". A reddish color would indicate the presence of precipitated iron. Stains on bathroom fixtures and on laundry are often associated with color also. Reddish-brown is ferric hydroxide (iron) will precipitate when the water is exposed to air. Dark brown to black stains are created by manganese. Excess copper can create blue stains.
Treatment : Color is removed by chemical feed, retention and filtration. Activated Carbon filtration will work most effectively to remove color in general. Anion scavenger resin will remove tannins, but must be preceded by a softener or mixed with fine mesh softener resin. See the headings Iron, Manganese, and Copper for information their removal or reduction.
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