With the development of industry and bioscience, more and more pollution is being discharged into the water and more and more viruses are being spread with the water flow.

Commercial and industrial water treatment rely deeply on filtration technology. There are plenty of filtration methods, among them, reverse osmosis is a very popular one.

introduction water

Why it is preferred by so many customers and what is the principle of reverse osmosis? Those questions can be answered by this blog, and this blog will help you to know more about the RO system.

What is reverse osmosis?

Before we talk about RO, you should know a story about seagulls. As early as 1950, a scientist in the United States inadvertently found that seagulls sipped a large mouthful of seawater while flying at sea, and spit out a small mouthful of seawater after a few seconds.

White Seagull flying over the sea

This led to doubts and research conducted to discover that there is a thin membrane inside the seagull, which is very delicately constructed. It is through this membrane that seagulls filter seawater into drinkable water, and seawater containing impurities and highly concentrated salts have been spitting out.

RO adopts membrane technology as seagulls, purifying water through a semi-permeable membrane. With the help of pressure, water passes through the membrane, and most impurities can be removed.

How does reverse osmosis work?

Now, we move back to the high school chemical class, realizing what osmosis is. Unlike reverse osmosis, osmosis is a natural phenomenon and happens every second in various environment, that a weaker salt solution will transition into a stronger salt solution during this phase. To make it more clearly, you can think about plants roots absorb water from solid.

ro working principle

After realizing osmosis, it is simple to understand the principle of reverse osmosis. Like its name, reverse osmosis means that a stronger salt solution transitions into a weaker salt solution with proper pressure. In this process, the not only pressure is needed, but also a semi-permeable membrane.

A membrane that permits certain atoms or molecules to flow through but not others is classified as semi-permeable. The majority of impurities and contaminants can be removed by this membrane.

Advantages of Reverse Osmosis Membranes

RO is a simple and energy-saving filtration method, it has lots of benefits. What’s more, RO is a environmentally-friendly filtration technology while it has high efficiency.

  • No heating required, no phase change
  • Simple equipment and small footprint
  • Easy to operate, a wide range of application
  • Low energy consumption and high efficiency
  • The high degree of automation, good quality of effluent
  • No pollution to the environment

What Impurities can RO Membrane Remove

RO can remove most the impurities in water, but include no bacteria. This is what you should notice, once bacteria and virus entered RO membrane, they would grow and damage the membrane. Below is a table, which shows removable impurities.

Typical impurities and removal percentage of RO membrane
Sodium 85-94%
Sulfate 96-98%
Calcium 94-98%
Potassium 85-95%
Nitrate 60-75%
Iron 94-98%
Zinc 95-98%
Mercury 95-98%
Selenium 94-96%
Phosphate 96-98%
Lead 95-98%
Arsenic 92-96%
Magnesium 94-98%
Nickel 96-98%
Fluoride 85-92%
Cadmium 94-98%
Barium 95-98%
Cyanide 84-92%
Chloride 85-92%

Why RO Membranes Need Pre-filtration


Liquids that are not pre-filtered contain many different impurities that can affect the performance and efficiency of RO membranes, and sometimes damage the entire RO system.

  • The particles in the liquid are easy to scratch the surface of the RO membrane, which will cause the RO membrane to be blocked or perforated.
  • The inorganic ions in the liquid are easy to scale on the surface of the RO membrane, requiring frequent cleaning.
  • The oxidant in the liquid easily causes the RO membrane to be oxidized and perforated.
  • Prefiltration for RO can improve the efficiency of the system and reduce maintenance time and costs for RO.


Before the raw water enters the RO membrane, different pre-filtration treatment methods are used for different processes to meet the influent water quality requirements of the reverse osmosis membrane.

Thus, stable and efficient operations can be maintained, and process investment and operating costs can be reduced. Remember to choose a suitable and powerful depth filter cartridge, depth pleated filter cartridge or high flow filter for your prefiltration.

How to Clean RO Membrane

When the water production of the RO membrane system drops, the pressure difference is high, and the raw water microorganisms exceed the standard to block the membrane pores, it is time to clean. There are generally two ways of cleaning.


Physical cleaning

To physically clean elements and improve the performance of membrane elements, automated flushing is used. Ultrasonic waves, gas-water mixing, and even vibration have all been used in the past.

The membrane elements are flushed by the influent water with appropriate pressure and high flow rate, and the contaminants and deposits attached to the membrane surface can be washed away in a short period of time.

Chemical cleaning

Choosing the appropriate chemical cleaning agent and cleaning scheme. In order to achieve the best cleaning effect, first perform low pH cleaning to remove mineral contaminants, and then perform high pH cleaning to remove organic matter.

The chemical cleaning method is best operated by professionals. Once the chemical cleaning agent is improperly selected or the method is incorrect, the pollution will deteriorate and even cause irreversible damage.

What Application Fields can RO Membranes be used for

water drop impact

Food industry

Formulation water, production water preparation, food processing concentration.

Beverage industry

Formulation water, production water, washing water preparation.

Pharmaceutical industry

Process water, preparation water, washing water, water for injection, sterile water preparation, drug concentration and separation.

Chemical industry

Production of water, wastewater treatment, concentration, and separation of valuable substances.

Power industry

Boiler feed water, circulating cooling water.

Electronics industry

Semiconductor industry ultrapure water, formula water.


Oil field injection water, advanced treatment of petrochemical wastewater, gas separation.

Drinking water engineering

Pure water preparation, drinking water purification.

How to select a suitable RO membrane?

Facing so many RO membranes of different sizes and types, it may be difficult for you to choose the appropriate one. The following table helps you to make a decision.

how to select ro

How to Reduce Waste Water in Reverse Osmosis Water System

Reducing the wastewater in the reverse osmosis system is to improve the recovery rate. On the basis of the existing reverse osmosis system and the premise that the water quality of the influent does not fluctuate, it can be realized by pretreatment technology, fine filtration, and pH adjustment.


As an efficient and reliable water treatment method, RO is becoming more and more popular in various industries. Not only for drinking water but also for industrial manufacturing. Due to its green and high-efficient working principle, large amounts of contaminants can be removed from the water.

conclusion ro

Brother Filtration, the experienced filtration expert, can provide you with RO membranes in various size and use. If you have any problems with reverse osmosis and want to pick RO membranes for your industry, please feel free to contact us.

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