The Splash

Integrated Treatment System Removes Iron, Arsenic and Radium in Wisconsin

The City of Elkhorn is a long-standing customer of Kurita America, utilizing equipment at multiple water treatment plants since the late 1970s. Elkhorn’s existing water treatment plants used aeration followed by pressure filtration and ion exchange, in series, to remove iron, arsenic and radium from the groundwater supply wells. When it came time to replace an aging treatment system, the city wanted to include detention into the new process for additional reaction time and more robust treatment. The Dualator® III was a good option to easily implement aeration, detention, and filtration into the new plant design, while offering additional benefits on operational flexibility, accessibility, and future expansion.

The Dualator III is a packaged groundwater treatment system that includes aeration, detention, and filtration. Kurita America worked with Baxter & Woodman, the city’s consulting engineer, to customize the equipment dimensions and features and accommodate their specific water treatment plant design. The unit’s height was adjusted to optimize footprint when including detention, which allowed space for future expansion with a second unit. The standard Dualator III design was also modified to include a free-standing aerator with loose-fill packing for more efficient oxidation and removal of dissolved gases. Further customization allows for independent operation of each filter cell, providing greater operator flexibility with the ability to remove a cell from service for backwash or maintenance while the others remain in operation. The filter section includes Kurita America’s Simul-Wash™ backwash method, which uses air and water simultaneously for optimal media cleaning while minimizing water use. 

After the Dualator III system removes iron and arsenic, radium is treated using ion exchange through a Kurita America RidION™ system consisting of three 9’ diameter vertical pressure vessels. Radium is a divalent cation, chemically similar to calcium and magnesium, and it adheres to the ion exchange resin by displacing sodium at available exchange sites. This process also softens the water by removing calcium and magnesium in the same manner. Ion exchange requires periodic regeneration with sodium chloride brine, and Kurita America provided the associated equipment for salt storage, brine makeup, delivery, and dilution. The water treatment plant design includes space for one additional ion exchange vessel to accommodate future expansion.

Kurita America also provided a PLC-based control system with panel enclosure and touch screen interface. The central control panel automates all operations for both treatment systems including functions for service, backwash, and regeneration.

The new treatment system was commissioned in early 2018 and has been providing reliable and safe drinking water to the City of Elkhorn ever since. The use of gravity filtration allows for ease of access through large manways, which can be opened during service and without draining the unit.  The calculated water savings for this installation are in the millions of gallons per year when comparing the Simul-Wash backwash process to conventional methods of similar duration. Further, the modular equipment design will streamline future expansion with the addition of similar treatment units, which positions the city for growth.