On-line dosing of Ammonium Biflouride for reduction of silica scaling on RO membranes

Abstract

The research conducted is based principally on the operation of pilot using membranes and various antiscalant doses. Membrane autopsies have been carried out which are a unique tool for characterizing the state of membranes and it is fundamental to guarantee the efficiency of chemical treatments. The results that are presented in this research refer to diverse studies related to problems with dissolved silica (also called “reactive silica”) and not to alumino-silicates (clays in colloidal form) also called “non-reactive silica”.The primary goal of this research is to investigate the effectiveness of using Ammonium Biflouride (ABF) as an anti-scaling agent in improving the performance of the RO membranes. ABF was used as on-line dosing with different doses for mitigation of scaling caused by silica (SiO2) on RO membranes. To study the efficiency of the anti-scaling agent, Scanning Electron Microscopy & Energy Dispersive X-ray Spectroscopy (SEM–EDS) were performed for all phases before and after using the anti-scaling agent on the used RO membrane surface. The main parameters measured were: silica, TDS. Flux loss was observed for the cross-flow RO membrane after filtration. ABF doses used were: 2, 4, and 6mg/l at constant pH=6 and the optimum dose was found to be 4mg/l.