Reverse osmosis and nanofiltration are two commonly used technology for water treatment. Both processes use a membrane to filter water and remove impurities, but they differ in certain ways. In this article, we shall walk you through those differences.
Reverse Osmosis
RO is a process in which water passes through a semi-permeable membrane, with the pressure applied on the side of the membrane opposite the direction of natural osmosis. This process removes multiple impurities, including dissolved salts, viruses, and bacteria. The water that collects after passing through the membrane is the permeate, while the water that is rejected by the membrane is called concentrate.
One of the advantages of reverse osmosis is its high efficiency. The pore size of RO membranes is typically in the range of 0.0001 to 0.001 microns, which means that it can remove even the smallest impurities from the water. However, this high level of filtration comes at a cost. RO systems require high pressure for the water to pass through the semi-permeable membrane, and they are also relatively inefficient, with a typical recovery rate of only 30-50%. This means that for every 100 gallons of water that enters the system, 30-50 gallons will be treated, and the rest will be discharged as concentrate.
Nanofiltration
Nanofiltration (NF) is a similar process, but it uses a membrane with slightly larger pores, typically in the range of 0.001 to 0.01 microns. This means that nanofiltration is not as efficient as reverse osmosis at removing impurities, but it can still get rid of various contaminants such as dissolved salts, viruses, and bacteria, much like RO. Unlike RO, though, nanofiltration does not require high pressure, and it has a higher recovery rate, typically in the range of 50-70%.
RO vs Nanofiltration
One of the main differences between reverse osmosis and nanofiltration is the type of impurities that they can remove. RO is more effective at removing water pollutants, such as dissolved salts and other small molecules, while nanofiltration is better at removing larger molecules, such as organic compounds and proteins along with, partial reduction of dissolved salts. This means that RO is often used for applications where the water needs to be very pure, like in the production of drinking water or pharmaceuticals, while nanofiltration is more commonly used for treating wastewater or other industrial applications.
Another key difference between the two technologies is the cost. RO systems are more expensive to install and operate than nanofiltration systems due to the higher pressure requirements and lower recovery rate. Nanofiltration systems are also more flexible, as they can be used with a wider range of feedwater quality, including high levels of turbidity and organic matter.
Conclusion
In summary, reverse osmosis and nanofiltration are two technologies commonly used for water treatment. Both processes use a membrane to filter water and remove impurities, but they certainly operate differently.
Permionics, a pioneer in Liquid Separation and Membrane Technology, uses both RO and nanofiltration along with other filtration processes to deliver customized wastewater management, process, and high-purity water solutions to an array of industries.
