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MOST COMMON WATER CONTAMINANTS
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( Its SOURCES and METHOD OF TREATMENT) |
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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) which will precipitate when the water is exposed to air. Dark brown to black stains are created by manganese. Excess copper can create blue stains. |
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Treatment - Color is removed by chemical feed, retention and filtration. Activated carbon filtration will work most effectively to remove color in general. |
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COPPER |
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Source – Copper (Cu+3) in drinking water can be derived from rock weathering, however the principal sources are the corrosion of brass and copper piping and the addition of copper salts when treating water supplies for algae control. Copper is required by the body for proper nutrition. Insufficient amounts of copper leads to iron deficiency. However, high doses of copper can cause liver damage or anemia.
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Treatment –Copper can be reduced with sodium form strong acid cation, resin (softener) dependent on the concentration. If the cation resin is regenerated with acid performance will be enhanced. Reverse osmosis or electrodialysis and activated carbon filtration helps in the removal of copper.
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HARDNESS |
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Source – The hardness of a water supply is determined by the content of calcium and magnesium salts. Calcium and magnesium combine with bicarbonates, sulfates, chlorides, and nitrates to form these salts. Sodium salts are also found in household water supplies, but they are considered harmless as long as they do bnot exist in large quantities. The calcium and magnesium salts which form hardness are divided into two categories: 1) Temporary Hardness (containing carbonates), and 2) Permanent Hardness (containing non-carbonates). Below find listings of the various combinations of permanent and temporary hardness along with their chemical formula and some information on each. |
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Calcium Carbonate (CaCO3) - Known as limestone, rare in water supplies. Causes alkalinity in water. |
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2.
Calcium Bicarbonate [Ca(HCO3)2] - Forms when water containing CO2 comes in contact with limestone. Also causes alkalinity in water. When heated CO2 is released and the calcium bicarbonate reverts back to calcium carbonate thus forming scale. |
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Magnesium Carbonate (MgCO3) - Known as magnesite with properties similar to calcium carbonate. |
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4.
Magnesium Bicarbonate [Mg(HCO3)2] - Similar to calcium bicarbonate in its properties. |
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PERMANENT HARDNESS SALTS |
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Calcium Sulfate (CaSO4) - Know as gypsum, used to make plaster of paris. Will precipitate and form scale in boilers when concentrated. |
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Calcium Chloride (CaCl2) - Reacts in boiler water to produce a low pH as follows: CaCl2 + 2HOH ==> Ca(OH)2 + 2HCl |
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Magnesium Sulfate (MgSO4) - Commonly known as epsom salts, may have laxative effect if great enough quantity is in the water. |
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4.
Magnesium Chloride (MgCl2) - Similar in properties to calcium chloride . |
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Treatment - Softeners can remove compensated hardness up to a practical limit of 100 gpg. If the hardness is above 30 gpg or the sodium to hardness ratio is greater than 33%, then economy salt settings can not be used. If the hardness is high, then the sodium will be high after softening, and may require that reverse osmosis be used for producing drinking water. |
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