Reverse osmosis (RO) is a water purification process that effectively removes high concentrations of minerals and salts from water in order to make it fit for use.
Reverse osmosis (RO) has gained a bad name over the last few years due to misconceptions about it stripping all minerals from water.
Ultimately, the purpose of reverse osmosis is to reduce mineral content in water when there is an excess of minerals.
Although it is true that all minerals can be removed, this is only the case when a client’s specific requirement calls for demineralised water. Certain industrial and pharmaceutical applications require demineralised water, for example.
What is Reverse Osmosis?
In order to understand reverse osmosis, it is important first to understand what ‘osmosis’ is.
Osmosis is a naturally occurring phenomenon: Water molecules pass through a semipermeable membrane of a cell to find equilibrium, balancing the concentration of salts.
In reverse osmosis, a water treatment system applies pressure to overcome the natural osmotic pressure in order to separate water from the saline solution through a membrane.
The net result of RO is a lower concentration of salt being on the one side, and a higher concentration on the other, the percentage of which depends on the type of membrane applied.
Categories of Reverse Osmosis
There are three main different categories of RO: Low pressure, brackish and seawater RO. The difference between these categories is primarily the mineral content of the water source. Other aspects that differentiate the sources from each other include organics, foulants, and plant location.
Low Pressure Reverse Osmosis
Low pressure reverse osmosis caters for a specific range of total dissolved solids (TDS): from 1 000 to 3 000 ppm. Low pressure reverse osmosis is suitable for rivers, boreholes and most wastewater applications.
Brackish Water Reverse Osmosis
This type of reverse osmosis has the capacity to treat a TDS of 3 000 to 20 000 ppm. It is usually implemented to purify highly brackish groundwater from boreholes as well as heavy industrial effluent.
Seawater Reverse Osmosis
Seawater typically has a TDS of anywhere between 20 000 and 50 000 ppm. This requires the highest rejection membrane available, a seawater membrane. A great deal of pressure needs to be applied for this type of RO, because seawater is high in salinity.
Benefits of Reverse Osmosis
A reverse osmosis system is one of the most extensive methods of filtration. It can remove up to 99,8% of dissolved solids from water, thus giving one access to previously unusable water.
Some benefits of reverse osmosis include:
Reduces harmful dissolved contaminants
Reduces high concentrations of ions such as calcium, chloride, magnesium, sodium and sulphate
Improves the taste and odour of drinking water
If you would like to know more about our reverse osmosis offering, feel free to contact us to discuss your challenges and requirements.