For the successful operation of a reverse-osmosis freshwater generator, the setting of the brine back pressure regulator is critical. What statement regarding the set point of this regulator is true?

Correct Answer: Option A — If the regulator setting is set too high, the membrane modules may be damaged. If the regulator setting is too low, the freshwater production will be too low.

The brine back pressure regulator maintains the required osmotic pressure across the membranes. Excessive pressure can physically rupture the membrane structure, while insufficient pressure fails to overcome the osmotic barrier, significantly reducing the permeate flux and overall freshwater production rate of the reverse-osmosis unit.