In 2007, AdEdge  was contacted by Pacific Advance Civil Engineering (PACE) to assist an American Indian tribe near San Diego that needed a packaged treatment system for uranium removal. The Barona Band of Indians owns and operates the water system serving the Barona Resort and Casino.
Combined, water from three existing wells had an average uranium concentration greater than 40 ug/L, exceeding the U.S. Environmental Protection Agency’s maximum contaminant level of 30 ug/L. AdEdge and PACE previously worked together to provide a pretreatment system for high levels of iron and manganese. The companies concluded—after studying both regenerative and throwaway options—that the regenerative approach was most cost-effective.
Designed for high-efficiency removal of naturally occurring uranium from groundwater supplies, the AdEdge AD92 system  has a twin 54-in. vessel configuration, with a design flow of 250 gal per minute (gpm) in parallel configuration. The system included automation to accomplish onsite regeneration of the media and automatic functions.
The PLC-based system was supplied with a control panel and a stainless-steel valve harness suitable for the ambient operating pressures over 120 psi. The system was furnished with a regeneration/brine system to regenerate the IX resin periodically on demand.
The complete system was packaged and delivered for site installation in October 2007. AD92 IX media is a strong-base anion resin with high capacity for uranium removal. It provides superior efficiency for uranium removal and greater resistance to organic fouling compared with other media. The negatively charged uranium species binds to the anion resin as it passes through the bed and is periodically regenerated with salt brine solution as the resin reaches a certain loading level. Periodic brine is permitted and approved for discharge by an onsite wastewater lagoon.
The system was placed into full-time operation in early November 2007, running at a flow rate of approximately 220 gpm and processing roughly 80,000 gal per day. To date, results reported by the site’s state-certified laboratory show uranium levels are consistently below detection (2 ug/L). Regeneration events are performed bimonthly, and the system is monitored regularly by the site’s operator.