Aplicación de electrocoagulación para eliminación de silicio en agua de enfriamiento

Abstract

Water supply for industrial use, despite its relatively small volume, became an important issue because of the intense competitiveness for water supply among users, and because of the quantity and diversity of contaminants it generates. Water for cooling towers used in thermoelectric plants amounts to the fairly low volume of 200 million m3. However, this sector begins to compete for water with other uses, especially in areas where the overexploitation of this resource is a major issue. Therefore, it is necessary to direct more efforts toward water treatment for reuse, taking into consideration the most suitable options in terms of cost and use of this water. The purpose of this work is within this present context. The study used electrocoagulation as an alternative technology to remove silica and other contaminants from the blowdown of cooling towers in a thermoelectric plant, and to prepare it for reuse through traditional chemical coagulation procedures. Chemical tests were carried out to determine the best iron doses that would be subsequently generated in the electrocoagulation cell. The iron doses were tested at the interval of 10 to 60 mg/L. A computer program was used to calculate the current necessary to generate iron in the cell to achieve the intended concentrations. The removal of silica obtained under different conditions showed that the simple addition of cationic polyelectrolyte in the effluent of the electrocoagulation cell reduces the silicon residual content in the water to levels that allow its recycling. This study concludes that considering the conditions under which the test was carried out and the type of water, the process proposed is favorable and feasible because it does not require the addition of other reactive substance that would increase the its costs.