Tuesday, August 2, 2011

How Reverse Osmosis Units Work

Osmosis are molecules passing through microscopic pores of a living or synthetic membrane. The concentration is different on this side of the membrane. The molecules are more concentrated on one side to pass thru the membrane, equalizing the concentrations on both sides.

osmosis replenish

Reverse osmois (RO) water filters make up a thin synthetic membrane with pores are large enough to let water molecules thru but too small for large molecules. The water pressure forces water thru the membrane but leaves large molecules that are contaminated behind. This is the reverse side because everything is not equal. The concentration of substances on the membrane lets the water pressure create pure water on one side, and pollutants on the other side. Then the pure water is released thru the RO output, and the polluted water and minerals goes down the drain.

OSMOSIS

It is a very slow process because the input water must pass thru small pores of the membrane. For home reverse osmosis it will take 2-3 hours for enough water to pass thru the membrane to produce one gallon of water. Because the it is so slow, they use small storage tanks holding 2-5 gallons. So, when you get water from the kitchen smile, it comes from the tank. Then it will slowly begin to refill tank.

Most these units purify waste water. They use 3/10 gallons of tap water to produce one gallon of purified water. The rest goes down the drain. These units have poor recovery rates. The efficiency of RO is in proportion to water pressure. The higher the pressure of the water, the higher the ratio of cleaned water to waste water.The pressure lower than 40lbs per square inch require a special booster pump to increase the pressure.

A unit can remove 80-90% to toxic minerals and chemicals, but cannot remove radon or chlorine (while a carbon filter can). Organisms that are larger than what is used for the mole-sized pore of a reverse osmosis membrane should be rejected, but it doesn't. So, because of this the units, by themselves, cannot be used to disinfect water.

These units have restrictions. They cannot be installed on a personal system unless the water has been disinfected. But if the tap water comes from the public system, the water system usually works well. There are two types of membranes for the reverse osmosis system (1) cellulose actute (CA) and the thin film composite (TFC) TFC out performs CA and last longer. They are also more expensive. The disadvantage is that they cannot tolerate chlorinated water. It must have an adequate pre-filter to remove the chlorine. The RO units are almost never used.

How Reverse Osmosis Units Work

OSMOSIS

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