Monitoring the integrity of reverse osmosis membranes

Several methods for monitoring the reverse osmosis (RO) membrane integrity were evaluated at a pilot-scale. These methods were classified as direct or indirect monitoring methods. The vacuum test was found to be a very promising direct monitoring method as it correlated well with virus rejection by the RO membranes. From the indirect real-time monitoring methods, On-line TOC monitoring was found to be more sensitive than on-line particle counting and conductivity monitoring. The use of more than one technique may be necessary to assure reliable operation of the membrane system.