The Effect of Feed Water Pressure on Reverse Osmosis Membranes
Feed water pressure itself does not affect salt permeation. However, increased feed water pressure raises the net pressure driving the reverse osmosis system, leading to increased permeate flow. Since salt permeation remains relatively constant, the increased permeate flow dilutes the salt passing through the membrane, reducing salt permeability and increasing desalination rate. When the feed water pressure exceeds a certain value, excessively high recovery rates increase concentration polarization, again leading to increased salt permeation. This offsets the increased permeate flow, preventing further increases in desalination rate.
The Effect of Feed Water Temperature on Reverse Osmosis Membranes
The permeate conductivity of reverse osmosis membranes is highly sensitive to changes in feed water temperature. Water flux increases linearly with increasing temperature; for every 1°C increase in feed water temperature, permeate flow increases by 2.5%-3.0% (based on 25°C).
The Effect of Feed Water pH on Reverse Osmosis Membranes
Feed water pH has almost no effect on permeate flow but significantly affects desalination rate. Desalination rate reaches its maximum between pH 7.5 and 8.5.
The effect of feed water salt concentration on reverse osmosis membranes
Osmotic pressure is a function of the concentration of salt or organic matter in water. The higher the salt content of the feed water, the greater the concentration gradient, the higher the salt permeability, and thus the lower the desalination rate.