Reverse Osmosis Units
The very name signifies what the process of reverse
osmosis is. While all other types of water filtration
devices reduce impurities in the water, the process of reverse
osmosis entails removal of water from the impurities. The
reverse osmosis unit achieves this by
forcing water through a specially constructed, semi-permeable,
nonporous synthetic membrane (usually cellulose acetate).
This membrane separates soluble and suspended particles
from the water and provides filtered water. The process
of reverse osmosis
removes a wide variety of substances from the water. Of
the impurities that are removed from water, more than 75
percent of these are sodium, calcium and chloride. Reverse
osmosis also may be effective in removing fluoride,
nitrate and some forms of arsenic. While most of the times
the membranes may last a year, its life truly depends upon
the quality of water entering the unit as this directly
impinges on the membrane.
The only reason why the water filtration systems based on reverse osmosis
units are expensive is because of the number of accessories that are needed
to operate them. They require in-line installation and a pre-filter to remove
all dirt and sediment. The pre-filter may be in the form of a mechanical filter.
To prevent buildup of contaminants on the membrane, if a back flush system is
employed - this further shoots up the cost of the system.
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