Reverse osmosis (RO)Process

What is Reverse osmosis

Reverse osmosis (RO) is a water purification technology that uses a partially permeable membrane to remove ions, molecules and larger particles from drinking water. In reverse osmosis, an applied pressure is used to overcome osmotic pressure, a colligative property, that is driven by chemical potential differences of the solvent, a thermodynamic parameter. Reverse osmosis can remove many types of dissolved and suspended chemical species as well as biological ones (principally bacteria) from water, and is used in both industrial processes and the production of potable water. The result is that the solute is retained on the pressurized side of the membrane and the pure solvent is allowed to pass to the other side. To be “selective”, this membrane should not allow large molecules or ions through the pores (holes), but should allow smaller components of the solution (such as solvent molecules, i.e., water, H2O) to pass freely.

Drinking water purification

Around the world, household drinking water purification systems, including a reverse osmosis step, are commonly used for improving water for drinking and cooking.

Such systems typically include a number of steps:

A sediment filter to trap particles, including rust and calcium carbonate
optionally, a second sediment filter with smaller pores.
An activated carbon filter to trap organic chemicals and chlorine, which will attack and degrade a thin film composite membrane.
A reverse osmosis filter, which is a thin film composite membrane.
Optionally, a second carbon filter to capture those chemicals not removed by the reverse osmosis membrane.
Optionally an ultraviolet lamp for sterilizing any microbes that may escape filtering by the reverse osmosis membrane.
The latest developments in the sphere include nano materials and membranes.

In some systems, the carbon prefilter is omitted, and a cellulose triacetate membrane is used. CTA (cellulose triacetate) is a paper by-product membrane bonded to a synthetic layer and is made to allow contact with chlorine in the water. These require a small amount of chlorine in the water source to prevent bacteria from forming on it. The typical rejection rate for CTA membranes is 85–95%.

The cellulose triacetate membrane is prone to rotting unless protected by chlorinated water, while the thin film composite membrane is prone to breaking down under the influence of chlorine. A thin film composite (TFC) membrane is made of synthetic material, and requires chlorine to be removed before the water enters the membrane. To protect the TFC membrane elements from chlorine damage, carbon filters are used as pre-treatment in all residential reverse osmosis systems. TFC membranes have a higher rejection rate of 95–98% and a longer life than CTA membranes.


AMI Point of Use Home RO Systems provide a continuous supply of clean, fresh drinking water. RO Systems are assembled on a heavy-duty SS bracket for wall-mounting under the sink or in a nearby location.

Eliminate up to 99% of dissolved solids, chlorine, fluoride, microorganisms and heavy metals such as barium, cadmium, chromium, lead and mercury from your water. Use RO purified water for drinking, cooking & ice for improved flavor and increased health benefits.
RO System can be used to supply filtered water to a refrigerator ice-maker/water-dispenser by inserting a branch tee fitting (sold separately) between the post filter and the faucet.
RO Systems are equipped with automatic shut-off valves to eliminate waste by closing the feed line when the tank is full.
Quick-Connect in/out connection points for easy installation. Complete installation kit and product manual included with every RO system.

These compact under the sink RO systems are complete with pre filters and post filters and come with a 4 gallon storage tank and installation kit. Each filter is designed to eliminate specific types of contaminants for cleaner and clearer drinking water. Our RO residential under the sink water filtration systems deliver high quality and better tasting drinking water. Please select from one of our series below.

About Zaighum Shah 90 Articles
Zaighum Shah is a mechanical engineer having more than 20 years of experience. Zaighum is specializing in product development in Sugar Mill industries. Zaighum has gone through all phases of mechanical engineering and it’s practical implementation. Zaighum has been solving most complex problems, designing new systems and improving existing models and systems.