Pretreatment of Coal Power Plant RO Retentate using AR floc 100

Abstract

The water purification process at Eskom includes a reverse osmosis (RO) treatment plant. There are several limitations to this process depending on the water characteristics. The most common problems limiting the success of water purification include scaling, biological fouling and corrosion. This study is mainly focused on reducing scale forming agents in the RO system. Scaling is the precipitation of calcium and magnesium salts onto the equipment, primarily the RO membrane. These salts start to precipitate once the salt concentration in the water is higher than the allowable solubility constant. These salts can be removed from the water by a process called coagulation-flocculation. The success of such process is partly dependent on the type of flocculant and the dosage used. In this study the performances of one coagulant namely Rheofloc 5023 in combination with three flocculants including Rheofloc 5414, Genesys genefloc and AR floc 100 were tested at various dosages for the reduction of conductivity assimilated with ions in the RO retentate from coal power plant was investigated at 40 and 60C. The AR floc 100 was determined to be the optimum flocculant required for the RO reject treatment. The optimum flocculant dosage resulted in 1 ppm along with a Rheofloc 5023 coagulant dosage of 0.7 ppm. Keywords—AR floc 100, RO retentate, flocculation, conductivity.