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 D — To overcome the osmotic pressure generated by the difference in solution concentrations.

Reverse osmosis relies on overcoming the natural osmotic pressure of seawater. The high-pressure pump must generate sufficient force to exceed this osmotic pressure, allowing water molecules to pass through the semi-permeable membrane while rejecting salt ions, which is essential for the desalination process to occur effectively.