Reverse-osmosis freshwater generators usually feature multiple membrane modules, typically of the spiral-wound membrane type. How are these multiple membrane modules piped?

Correct Answer: Option B — The multiple membranes may be connected in series, parallel, or in some combination of series and parallel.

Reverse osmosis systems utilize modular membrane configurations to optimize throughput and purity. Depending on the specific vessel requirements and desired water quality, these modules can be arranged in series to increase rejection rates, in parallel to increase total output, or in complex combinations to balance both efficiency and capacity.