Method and system for monitoring reverse osmosis membranes

A method for monitoring membrane scaling, the method comprising:

• providing a reverse osmosis membrane in a reverse osmosis unit that receives a feed stream and discharges a concentrate stream;
• providing a reverse osmosis monitoring cell having a visually-observable RO membrane with a surface on an active feed side, wherein the visually-observable RO membrane is distinct from the reverse osmosis membrane in the reverse osmosis unit;
• passing a sample stream from either the feed stream or the concentrate stream of the reverse osmosis unit across the surface of the visually-observable RO membrane;
• using a mirror arrangement configured for specular reflection, directing light across at least a portion of the surface of the visually-observable RO membrane and along a direction substantially parallel to the surface of the visually-observable RO membrane to provide dark field illumination thereof;
• collecting visual data from the illuminated portion of the surface of the visually-observable membrane, wherein the collected data indicate the presence and degree of scaling on the surface of the visually-observable RO membrane;
• conveying the collected visual data to a data processing system;
• and
• interpreting the collected visual data with the data processing system to determine the extent of scaling on the reverse osmosis membrane in the reverse osmosis unit.

A reverse osmosis (RO) monitoring cell for use in monitoring membrane scaling on a RO membrane in a RO unit that receives a feed stream and discharges a concentrate stream, the monitoring cell comprising:

• a visually-observable RO membrane having a first surface on an active feed-side;
• a flow head configured and arranged to direct a sample stream from either the feed stream or the concentrate stream of the RO unit across the first surface of the visually-observable membrane;
• an optical window in the flow head through which the first surface of the visually-observable membrane is visible;
• and
• a mirror arrangement in the monitoring cell, and configured and located relative to the first surface of the visually-observable membrane so as to specularly reflect light from a light source across at least a portion of the first surface of the visually-observable membrane to provide dark field illumination thereof, wherein the mirror arrangement comprises a first portion and a second portion, the light from the light source passes through the optical window, the first portion reflects the light from the light source so as to pass through scaling on the first surface of the visually-observable membrane, and the second portion reflects the light that passes through the scaling through the optical window, thereby making the scaling on the first surface visible through the optical window.