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IRON (Fe)
Iron concentrations as low as 0.3 ppm will cause staining. The iron concentration, together with the flow rate demand and the consumption rate of the water determines the
basic size filter system. The higher these factors are, the larger the required system. The filter system is capable of filtering out the three main types of iron found in water
supplies: Soluble iron (also known as “clear water” or ferrous iron), precipitated iron (also known as “red water” or ferric iron) and bacterial iron (also known as iron bacteria).
There is no apparent upper limit of iron concentration for the filter, but special care must be taken when selecting a filter model if your water has a combination of high iron,
very low pH and/or manganese.
MANGANESE (Mn)
The presence of manganese can be bothersome, even for a chemical free iron filter. As little as 0.05 ppm of manganese can produce a brownish or black stain. The ability of the
filter to remove manganese depends on its concentration and the pH of the water.
Manganese tends to “coat” the filter media, rendering it incapable of increasing the pH, and therefore ineffective in removing either the iron or the manganese. Manganese,
however, will precipitate in the filter bed when the pH is increased. To accomplish this a special “MN” type media can be provided that contains additional quantities of the pH
raising component (“MN adder”). The use of “MN” type media is for applications where the manganese is not more than 1.5 ppm, and the pH is at least 6.5.
pH
The pH of water measures its acidity or its alkalinity. Water with a pH of less than 7.0 is acidic, above 7.0 it is alkaline, and a pH of 7.0 is neutral. The lower the pH value is
below 7.0 the greater the acidity, and the higher the pH value is above 7.0 the more alkaline. Acidic water (pH less than 7.0) is corrosive to pipes, appliances, etc. A pH of 7.0 or
higher facilitates iron removal — which is why the filter is designed to increase the pH when it is less than 7.0.
TANNINS (Humic Acid)
Tannins (also known as humic acid) which are present in some water supplies, are the result of decaying vegetable matter. If the tannin concentration is above approximately
0.5 ppm, it will form a sticky coating on the media, thus rendering it incapable of filtering the iron. A chemical free iron filter is not recommended under this condition. If the
tannin concentration is less than 0.5 ppm, a chemical free iron filter may be installed.
HYDROGEN SULFIDE (H2S)
Hydrogen sulphide (often referred to as “sulphur”), is easily detectable by its objectionable “rotten egg” odour. Sulphur corrodes iron, brass, copper and silver. A chemical free
iron filter is capable of removing sulphur in concentrations of up to 3 to 5 ppm. Whenever hydrogen sulphide is present, backwashing must be performed at more frequent
intervals.
CONTAMINANTS FOUND IN WATER
Summary of Contents for 89 BAF
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