For the successful operation of a reverse-osmosis freshwater generator, why is the high pressure pump required to operate in the 750 to 1200 psig range for a discharge pressure?

Correct Answer: Option C — To overcome the osmotic pressure generated by the difference in solution concentrations.

Osmotic pressure is the minimum pressure required to prevent the flow of pure solvent into a solution through a semi-permeable membrane. In seawater desalination, the high-pressure pump must exceed this osmotic pressure to reverse the natural flow, allowing freshwater to pass through the membrane into the permeate collection system.