Ro Membranes

RO Membranes

Water is essential to life, and as global populations grow, the demand for potable, clean water is also growing. Among the many technologies invented to assist in meeting this demand, Reverse Osmosis (RO) is one of the more effective methods. The most critical component of RO systems is the RO membrane. It is important to understand what an RO membrane is, how it works, the materials from which it is made, and how it fits into all water purification systems to provide clean water for residential, commercial, or industrial purposes.

What is an RO Membrane?

An RO membrane is a semi- permeable barrier, with the purpose to take water and contaminants, and filter them apart from each other, by employing pressure to force water from one side of the membrane to the other, rejecting unwanted ions and molecules of dissolved materials. RO membranes reject impurities, such as dissolved salts, bacteria, viruses, organic compounds, heavy metals, and many others.
An RO membrane only allows specific passage of water molecules through it, as the membrane has infinitely microscopic pores which do not allow tiny dissolved salts and pathogens to pass through. The reason it is called reverse osmosis is because that is the process we are actually reversing.

How Does It Work?

In a reverse osmosis (RO) system, water purification is a multi-stage, unit operation. Water passes through a series of pre-filters that remove sediment, dirt and chlorine. This is an important first step because it removes contaminants that could damage or plug the RO membrane. After it passes through the pre-filtration, the water is pumped; when enough pressure is applied, water is forced through a semi-permeable RO membrane. This RO membrane has incredibly small pores, allowing only water molecules to pass through, not contaminates, such as dissolved salts, bacteria, viruses, heavy metals and organics. The water that passes through the RO membrane is called "permeate," and the water remaining on the concentrated side of the membrane with rejected impurities is called "brine" or "concentrate" and typically flushes down the drain. After separation occurs, very often, the permeate will go through a post filter (commonly activated carbon) to improve the taste and odor before delivery. Although it may be complex, the multiple stages of purification ensure it is highly effective, producing clean, safe and good-tasting water!

Types of RO Membranes

There are several types of RO membranes that are suitable for specific purposes:

Thin-Film Composite (TFC): Used everywhere in everything RO.
Cellulose Acetate (CA): They were used in the early days of RO and have an advantage of being less sensitive to chlorine but they are not as effective as unwanted contaminants as the TFC.
Low energy (LE) membranes: these membranes have been developed more recently to operate at less pressure for low energy purposes. Many home water systems take advantage of low energy membranes to conserve energy.
High rejection membranes: this type is not often considered but in some instances you need very high purity and low levels of conductance or contaminants. Pharmaceutical processes, high technology electronics, etc. uses high rejection membranes.

Advantages of RO Membranes

Effective Removal of Contaminants: Will remove 99% or more of dissolved salts and impurities.
Improved Taste & Odor: Will remove chlorine and organic constituents.
Versatile: Can be used with seawater applications, brackish water, and tap water.
Environmentally Friendly: Less reliance on bottled water and less plastic waste.
Cost-Effective: The initial cost is higher, but will be low maintenance costs over time.

RO membranes are the stars of water purification. If you are using a small-scale under-sink filter at home, or if you manage a large corporate desalination facility, what you need to know is how to use RO membranes and how to look after them so you’ll have consistent quality water! Water scarcity is becoming more reality. As a result, RO technology is going to play an even larger role in securing a safe and sustainable water future.