Slide 2:
The process of osmosis through semipermeable membranes was first observed in 1748 by Jean Antoine Nollet. For the following 200 years, osmosis was only a phenomenon observed in the laboratory. In 1949 the University of California at Los Angeles (UCLA) first investigated desalination of seawater using semipermeable membranes.
Slide 3:
The membranes used for reverse osmosis have a dense barrier layer in the polymer matrix where most separation occurs. In most cases the membrane is designed to allow only water to pass through this dense layer while preventing the passage of solutes (such as salt ions). This process requires that a high pressure be exerted on the high concentration side of the membrane, usually 217 bar (30250 psi) for fresh and brackish water, and 4070 bar (6001000 psi) for seawater, which has around 24 bar (350 psi) natural osmotic pressure that must be overcome.
Slide 4:
Osmosis describes how solvent moves between two solutions separated by a semipermeable membrane to reduce concentration differences between the solutions. When two solutions with different concentrations of a solute are mixed, the total amount of solutes in the two solutions will be equally distributed in the total amount of solvent from the two solutions. Instead of mixing the two solutions together, they can be put in two compartments where they are separated from each other by a semipermeable membrane.
Slide 5:
Reverse osmosis is extensively used in the dairy industry for the production of whey protein powders and for the concentration of milk to reduce shipping costs. In whey applications, the whey (liquid remaining after cheese manufacture) is pre-concentrated with RO from 6% total solids to 10-20% total solids before UF (ultrafiltration) processing. The UF retentate can then be used to make various whey powders including WPI (whey protein isolate) used in bodybuilding formulations. Additionally, the UF permeate, which contains lactose, is concentrated by RO from 5% total solids to 1822% total solids to reduce crystallization and drying costs of the lactose powder.
Slide 6:
Large reverse osmosis and multistage flash desalination plants are used in the Middle East, especially Saudi Arabia. The energy requirements of the plants are large, but electricity can be produced relatively cheaply with the abundant oil reserves in the region. The desalination plants are often located adjacent to the power plants, which reduces energy losses in transmission and allows waste heat to be used in the desalination process of multistage flash plants, reducing the amount of energy needed to desalinate the water and providing cooling for the power plant.