The IVIIEXR process is based on a new patented ion exchange resin developed by ORICA. The resin combines a number of anion exchange resin features intended to result in efficient removal of natural organic material. It has a polyacrylic, macroporous structure with a medium pore size and porosity. It also contains a high concentration of strong base, quaternary ammonia functional groups.’
The IVIIEXR resin particle size is 2-5 times smaller than conventional resins, which are restricted to larger sizes because they tend to be used in fixed bed configurations where head losses need to be minimized. Smaller resins show higher rates of exchange because they have larger external specific surface areas. Accordingly, they have more active sites on the surface of the resin beads. As a result, the reliance on slow, intraparticle diffusion associated with active sites inside resin beads is correspondingly reduced.
A major feature of the resin that allows it to be used in a batch treatment mode is the high content of a magnetic compound which is integrated into the resin structure. Because of this magnetic property, the resin beads can be recovered after they are allowed to separate from the suspending solution by gravitational settling. It has been well established23’4 that, for most natural waters, the concentration of natural organic material (dissolved organic carbon [DOC]) tends to control the coagulant dosage required for effective turbidity (particle) removal.