Reverse Osmosis Explained
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What Is Reverse Osmosis?
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Reverse osmosis is a process in which pure water and contaminated water are separated through the use of a semipermeable membrane. This process is an essential method used in water purification systems. It is an effective method of removing water impurities, including chlorinated pesticides, turbidity, dissolved solids, toxic heavy metals such as lead and radium and many other impurities. Reverse osmosis is used in many applications, including waste water purification, dialysis, maple syrup production, reef aquarium keeping, hydrogen production and car washing. It is also used extensively in the food industry as well as in the wine industry.
The Water Purification Process
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Water purification processes that use reverse osmosis undergo several steps in order to separate impurities from pure water. The first step involved is the pre-filtration process, in which the largest particles are removed. Usually, a carbon or activated carbon-based filter is used to sift particles. The water that remains from this first step then passes through a semipermeable or extremely thin membrane, which usually has a dense barrier in the polymer matrix. This design is specifically formulated to allow only liquid molecules to pass through, further filtering impurities that may not have been eradicated during the pre-filtration process. Pressure is applied to ensure that purified water passes through the membrane to the other side. Purified water is then placed in a holding tank and stored there for drinking purposes.
How Reverse Osmosis Works
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Reverse osmosis is literally the complete opposite of osmosis, a natural phenomenon that is the movement of water from an area of higher concentration to an area of lower concentration. While osmosis occurs naturally, reverse osmosis is induced through the application of pressure. The process follows the scientific concept that when two aqueous solutions coming from different levels of concentration are divided by a semipermeable membrane, liquid flows through the membrane toward the direction that has a higher concentration because of osmotic pressure. To overcome the osmotic pressure and to effectively reverse the flow of water, enough pressure must be applied. This is how reverse osmosis works. Reverse osmosis pushes the water molecules toward the other side of the membrane.
Importance of the Membrane in Reverse Osmosis
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The membrane is an essential material in the process of reverse osmosis. Without it, reverse osmosis cannot be done. The membrane is the main material that is responsible for completing the process of reverse osmosis, separating the impurities from pure water. The membrane filters and removes bacteria, viruses, salts, harmful chemicals, dissolved solids and all the other impurities and contaminants in the water. Membranes used in commercial reverse osmosis are usually made of cellulose acetate, polyamide and polysulfonate. The skins of these membranes serve as active barriers to impurities, while at the same time allowing pure water to pass through.
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