Reverse Osmosis

Introduction to Reverse Osmosis

Water filtration technology is the process of purifying water through the use of filters, reverse osmosis (RO) filtration is a much more advanced method of filtration technology by passing water through a semipermeable membrane under pressure. This method of advanced water treatment is used in both drinking and wastewater treatment to remove unwanted ions, molecules, minerals and pathogens. Reverse osmosis technology is however an infrastructure with a high cost for both implementing on a large scale as well as for maintenance.

 History

Reverse Osmosis was first observed in a laboratory setting in 1748 by Jean-Antoine Nollete through the use of a pig’s bladder to demonstrate that a solvent could pass through a semipermeable membrane using natural osmotic pressure until a dynamic equilibrium is reached on both sides of the membrane. Since the original proof of concept RO technology has developed greatly leading to 1949 when the first group of scientists, at University of California at Los Angeles and the University of Florida, proposed the use of osmosis and semipermeable membranes for the desalination of seawater. Though the use of RO to separate unwanted molecules to produce fresh water was proven to possible during the 1950s and pilot RO schemes were run during the 1960s, it was not until 1972  when John Cadotte, an inventor and filtration chemist, developed a composite polyamide filtration membrane that was suitable for industrial applications. Since this initial breakthrough in the industrial application of RO technology the use of this technology has spread throughout the world with over 16,000 operational RO in desalination plants across 177 countries with many other RO filters used in other areas of industry.


 How it works

Reverse Osmosis works through forcing a solvent from a region of high solute concentration to a region of low solute concentration through a semipermeable membrane using pressure to exceed osmotic pressure. As such contaminated water is situated on one side of a semipermeable membrane and once pressure is applied to one side of the membrane, exceeding the osmotic pressure, the water passes through the membrane producing a pure water devoid of any contaminants on the low pressure side of the membrane.

 Uses of RO

There are many applications for RO technology the most namely being:

  • Desalination - RO technology was initially developed in an effort to reduce the strain on freshwater resources through the production of drinking water from seawater. As has been previously stated since the first industrial use of RO in the 1960s and 70s there has been a dramatic increase in the usage of this technology exceeding 16,000 desalination plants across the globe producing 95 million m3/day of freshwater.

  • Quaternary treatment of wastewater - The application of RO technology in wastewater treatment was introduced as an effort to produce an effluent that is completely treated to meeting environmental standards before it is discharged from a treatment facility. RO is applied following the activated sludge process and the other filtration technologies to further treat the wastewater, producing an effluent suitable for discharge into surface water

  • Water reuse and recycling - The water produced through RO is often reused throughout industrial processes including its usage in power generation where RO water is used to produce stream that does not contain any other products that may reduce the efficiency of energy production.

  • Pharmaceutical production - the water used throughout the production of pharmaceuticals is often treated to increase the purity of the water removing any products that may impact the overall specifications for pharmaceuticals. RO produces a pure water that does not contain the products, as such it is an extremely suitable usage for this pure water 

  • Food and beverage production - RO technology is used throughout the food and beverage production industry as water is a resource to reduce the overall impact of a company on freshwater resources. One of the most notable uses of RO technology in the food and beverage industry comes in the form of NEWater. NEWater uses RO technology throughout its treatment process to produce a clean reclaimed potable water from wastewater in an effort to improve sustainability in regions of increasing water scarcity issues.