What is a Reverse Osmosis Membrane?
Derwent Water Systems use only the best Reverse Osmosis membranes available. This enables us to design each RO specifically for each application maximising the efficiency of our RO systems and saving customers money. We use thin film composite spiral wound membranes. The most important factors of a Reverse Osmosis membrane are as follows:
1) It must comprise of a very thin layer of material (Polyamide ). The thinner this membrane the better the efficiency. The overall membrane resistance is directly proportional to its thickness.
2) It must have a narrow range of pore sizes to be ‘selective’ in the removal of salts etc.
3) It must have a high porosity.
Most Reverse Osmosis membranes comprise of 2 layers. The first layer being the ‘active’ filtering layer and the second layer comprising of a very porous supporting layer which is bonded onto the membrane purely for mechanical strength. Other type of membranes as used in Nano filtration and microfiltration include:
- Pleated filter cartridge
- Plate and frame
- Hollow fibre
It is necessary to encourage turbulence on the surface of a membrane to encourage the flux value. Below is a table which highlights Turbulence Promotion: