Pure water made greener

Physical and chemical improvements in ion exchange technology bring about a drastic reduction in the amounts of chemicals required and the environmental impact of the process. Developed to reduce costs and the amount of effluent generated in the production of high purity water, the techniques are of interest to anyone engaged in chemical processing. Ion exchange is the most widely used process to remove small amounts of chemical from a water-based stream. Applications range from water softening and purification, to the processing of 'spent' nuclear fuel rods. In all cases, it uses a container of resin beads to absorb the chemical of Interest, followed by elution, in which a strong chemical solution is pumped through the container to release the initially absorbed chemical at high concentration. Vivendi Water Systems, now renamed Elga Process Water under renamed parent, Veolia Environnement, has over 60 years of water treatment experience under the brand names, Permutit, Dewplan, Ionpure, Elga, USF, Chiltern and Memcor. It built its first industrial demineralised water plant in 1937. Its newest technology, patents applied for, is employed in its latest development, the Rapide Strata range. At the product launch, it was explained that the new process includes both improvements in resin chemistry, and in its introduction of elution chemicals in a series of pulses, which it was said, "Gives the resin a better work out." This uses elution chemicals more efficiently, so that a higher proportion is used to displace the chemicals held in the resin, and less passes straight through and into the effluent. The amount of elution chemicals needed is further reduced by pre-determining the amount of chemicals required for elution on a particular occasion, and only using that much. The net result is claimed to be running and effluent costs up to 40% lower, and chemical efficiencies up to 50% higher, than conventional deionisers. The process produces high quality deionised water with resistivity higher than 0.5Mohm.cm, more than sufficient for most healthcare, surface finishing and utility applications. Where even higher quality deionised water is required, Rapide Strata Plus machines incorporated a 'Hipol' polishing device to deliver water with up to 18.2Mohm resistivity, the theoretical maximum possible with pure pH7 water. Effluent is normally ph6 to 9. Rapide Strata and Rapide Strata plus products are each available in three models giving flows of up to 18m3/h and all models are skid mounted and pre-commissioned to minimise installation costs and start-up time. Operation is fully automatic under PLC control. Elga Process Water Sales Email Pointers * New ion exchange technology allows high purity water to be made at 40% less cost and with a chemical efficiency up to 50% higher, halving chemicals in the effluent * The advances stem from improvements in resin chemistry, pulsing application of eluting chemicals, and pre-determining the amount of chemicals needed for elution.