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Did
you know?
Reverse osmosis is the finest water filtration method known. This process will
allow the removal of particles as small as ions from a solution. It is used
to purify water and remove salts and other impurities in order to improve the
color, taste or properties of the fluid. R.O. uses a membrane that is semi-permeable,
allowing the fluid that is being purified to pass through it, while rejecting
other ions and contaminants from passing.
This technology uses a process
known as crossflow to allow the r.o. membrane to continually clean itself. This
is the reason of why an r.o. element can last many years before clogging or
need replacement. This
water purification process requires a driving force to push the fluid through
the membrane, and the most common force is household water pressure or pressure
from a booster pump. The higher the pressure, the larger the driving force and
efficiency.
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CHLORIDE AND SULFATE
Almost
all natural waters contain chloride and sulfate ions. Their concentrations
vary considerably according to the mineral content of the earth in any
given area. In small amounts they are not significant. In large concentrations
they present problems. Usually chloride concentrations are low. Sulfates
can be more troublesome because they generally occur in greater concentrations.
Low to moderate concentrations of both chloride and sulfate ions add palatability
to water. In fact, they are desirable for this reason. Excessive concentrations
of either, of course, can make water unpleasant to drink.
The EPA Secondary Drinking
Water Regulations recommend a maximum concentration of 250 mg/1 for chloride
ions and 250 mg/1 for sulfate ions (expressed as Cl- and S04--,
not as CaC03).
Water containing calcium
sulfate ions is likely to have a characteristic taste ... somewhat bitter
and astringent. In fact, it has been compared to the way dissolved gypsum
might taste in water. When 30 to 40 grains per gallon of calcium sulfate
are dissolved in water, most people can detect the taste.
If equal amounts of
magnesium sulfate or sodium sulfate are dissolved in water, the taste
would not be noticeable. Both possess definite laxative effects in concentrations
above 30 grains per gallon. In this way, they can be troublesome especially
to people not accustomed to such water. In addition to their laxative
properties and possible medicinal taste, sulfate water can mean extreme
hardness, large amounts of sodium salts or acidity. Alone or together,
these can pose special problems in the conditioning of water.
Chlorides give water a salty taste. At what concentrations this becomes noticeable
again depends upon the individual. In large concentrations chlorides cause
a brackish, briny taste that definitely is undesirable. Although chlorides
are extremely soluble, they possess marked stability. This enables them
to resist change and to remain fairly constant in any given water unless
the supply is altered by dilution or by industrial or human wastes. Both
chlorides and sulfates contribute to the total mineral content of water.
As indicated above, the total concentration of minerals may have a variety
of effects in the home. High concentrations of either sulfate or chloride
ions add to the electrical conductivity of water.
Chlorides and sulfates
can be substantially removed from water by reverse
osmosis. Deionization (demineralization) or distillation will also
remove chlorides and sulfates from water, but these methods are
less suitable for household use than reverse osmosis.

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