Company Develops New DOC Removal System

The world's first continuous magnetic ion exchange process, employing a patented high capacity ion exchange resin called MIEXRegistered, has been made available to the U.S. market, according to David Day, business manager of Orica Watercare, a division of Orica Australia, Pty Ltd.

Orica Watercare will operate in the U.S. as a division of Orica U.S. Services Inc. and be based in that corporation's offices in Denver.

The process uses the patented high capacity MIEXRegistered resin in a magnetic ion exchange system to remove Dissolved Organic Carbon (DOC) from drinking water. Pilot plant trials at Wanneroo in Western Australia have led to the construction of a 55 MGD treatment plant there. Trials are also under way in the United States.

The process - which was developed by a joint effort with Australia's Commonwealth Scientific and Industrial Research Organization (CSIRO) and South Australian Water Corporation - can cut the cost of DOC removal by as much as 50 percent and reduce downstream chemical sludge by as much as 80 percent, company officials said.

The process differs from conventional ion exchange processes because the overall ion exchange capacity is continuously maintained, resulting in a consistently high water quality with a controlled DOC level.

"This new process can significantly improve water quality and open up a brand new market in the United States and around the world," Day said.

The system is designed for the removal of DOC at the front end of a water treatment plant in a stirred contactor, much like a flash mixer in a conventional water treatment plant. The resin beads are significantly smaller than conventional resin beads, to provide maximum surface area and allow rapid DOC adsorption kinetics in the contact vessel.

In the process, a magnetic component is dispersed within the resin particle structure so that, when passed to a settler, the fine resin beads agglomerate into larger, fast-settling particles. Resin recovery rates of greater than 99.9 percent are achieved at settler rise rates of over 4 gpm/ft2.

Most of the settled resin is recycled to the front of the process while a small sidestream is removed and sent for regeneration with a NaCl brine solution.

Orica has been conducting a pilot program at St. Paul Regional Water Services, and also performing lab tests at the Wade G. Brown Water Treatment Plant in Durham, N.C., comparing results with performance data collected in Australia. St. Paul draws its water from Lake Vadnais, where the influent Total Organic Carbon (TOC) ranges between about 6 and 15 mg/l.

"The initial results of these tests have been highly favorable," said Michael F. Bourke, who will manage Orica Watercare's U.S. operations.

"We can achieve the same results at both large and small treatment facilities across the United States," Bourke added.

Orica Watercare is the largest supplier of water treatment and industrial chemicals in Australia and New Zealand. Orica Australia Pty. Ltd. is the world's largest supplier of commercial explosives.