MIEX-DOC Process

The MIEX-DOC Process is a continuous ion exchange process designed for the removal of dissolved organic carbon (DOC) from a source water. The process employs a patented magnetized ion exchange resin, the MIEX-DOC Resin.

The MIEX-DOC Resin has been developed to enable adsorption of DOC to occur in a stirred contactor, much like a flash mixer in a conventional water treatment plant. The MIEX-DOC Resin beads are much smaller than conventional resin beads at around 150 micron, to allow rapid DOC adsorption kinetics

in the contactor vessel. Under mixing conditions, the resin beads are dispersed to provide the maximum surface area available for adsorption of DOC.

The resin suspension then passes to a separating stage where the resin is recovered and recycled. A magnetic component is dispersed within the resin particle structure so that when passed to a settler the fine resin beads rapidly agglomerate into larger, fast settling particles. Resin recovery rates of greater than 99.9% are achieved at settler rise rates of over 10m/hr. Most of the settled resin is recycled to the front of the process while a small sidestream is is removed and sent for regeneration. MIEX-DOC Resin is regenerated in a brine (NaCl) solution where adsorbed organics are substituted for chloride ions (see The MIEX-DOC Resin).MIEX-DOC Process Plant

The MIEX-DOC Process differs significantly from conventional ion exchange processes. In conventional ion exchange columns, as the ion exchange capacity is progressively exhausted, the water produced deteriorates in quality. The leakage of undesired ions eventually reaches the point where product water is not of an acceptable quality. At that point, the column has to be taken off-line and the resin regenerated. In contrast, the overall ion exchange capacity in the MIEX-DOC Process is continuously maintained. As a consequence, the treated water from the MIEX-DOC Process is of a consistent quality with breakthrough of DOC controlled at a predetermined level.

Unlike conventional ion exchange processes, the MIEX-DOC Process does not require pre-treatment for solids removal. The MIEX-DOC Process can therefore be used to treat raw water at the start of a treatment chain or as a polishing step at the end. High turbidity levels do not interfere with the adsorption of DOC. When used to treat raw water, further treatment downstream of the MIEX-DOC Process is required for turbidity removal. Because the MIEX-DOC Process causes a slight increase in turbidity due to a small amount of resin carry over from the settler, a subsequent filtration stage is required.