The Performance of Anti-Scalants on Silica-Scaling in Reverse Osmosis Plants

Irreversible membrane scaling caused by silica remains a severe problem in many reverse osmo-sis plants. The engineering task is to find out the appropriate anti-scalant agent and its optimal dosage. Because suitable test methods are missing, a new membrane-based test method was de-veloped. The fully automatically controlled test set-up and the test procedure are described. The effectiveness of 13 anti-scalants for silica was measured at different pH-values between 7.6 and 9.0 and with silica concentrations from 120 mg/l to 275 mg/L. The results show that two of the anti-scalants investigated in this paper have a significant anti-scaling effect for silica.