14-16: Calcium Removal from Cooling Tower Water by Ion Exchange

Make-up waters with elevated calcium hardness tend to increase the risk of scaling in circulating cooling systems where the concentration of calcium increases through higher Cycles of Concentration (COC). To prevent calcium scaling, cooling towers control the calcium concentration in circulating loops by adjusting the volume of liquid blow-down. In cases where calcium is the blow-down determining constituent, the build-up of calcium can severely limit the extent of water re-use. With increased water scarcity in many areas of the SE USA, the need to reduce water consumption in cooling towers by increasing the COC is of significant importance. An ion exchange based technology has been developed to selectively remove calcium from aqueous streams effectively eliminating calcium as the limiting constituent for COC. A case study will be presented where calcium is the limiting constituent for COC and the technology is shown to significantly reduce water consumption by increasing the COC.