Identifying the Causes and Possible Solutions to High Recovery RO Membrane Fouling

High recovery RO techniques are being developed which can recover from 90 to 98% of the water leaving a relatively small volume concentrated brine that can be cost effectively managed. In order to attain such high recovery, special precautions and pre-treatment procedures are necessary to minimize fouling, including softening and the use of antiscalants. The use of Electron Microprobe (EMP) techniques in combination with high ionic strength geochemical modeling is a powerful combination in which the membrane foulants can be identified. Two high recovery RO case studies are presented where membrane fouling has occurred and the EMP/modeling approach has been employed. The results of the evaluations showed that in both cases, amorphous silica was the cause of the fouling.