A reverse-osmosis process is to be designed to handle a feed flow rate of 100gal/min. Three designs have been proposed, differing in the % recovery of potable water from the feed:

Design 1: A single stage consisting of four units in parallel to obtain a 50% recovery

Design 2: Two stages in series with respect to the retentate (four units in parallel followed by two units in parallel)

Design 3: Three stages in series with respect to the retentate (four units in parallel followed by two units in parallel followed by a single unit) Draw the three designs and determine the percent recovery of potable water for Designs 2 and 3.