Magna Water Company (MWC), which serves potable water to approximately 28,000 customers in the northwest section of Salt Lake County, Utah, has been affected both by perchlorate and arsenic contamination in its groundwater supplies. A six-month pilot study conducted in 1999-2000 demonstrated that in the presence of high silica and sulfate levels, electrodialysis reversal (EDR) would be the most feasible alternative for removing perchlorate and arsenic.

A substantial obstacle to the effective implementation of EDR treatment for perchlorate and arsenic removal is the need to treat and/or dispose of the associated perchlorate-laden concentrate. Bench-scale research conducted by Carollo Engineers and funded in part by the American Water Works Association Research Foundation investigated the use of a suspended growth and fixed-film biological processes to destroy perchlorate that reaches the headworks of Magna’s WWTP via the disposal of perchlorate-laden concentrates to the sewer.

The US EPA funded a seven-month pilot study at Magna’s Barton Well Field in 2004-2005 to demonstrate the efficacy of using a FXB biological reactor to remove perchlorate from an EDR concentrate stream that has been blended with a municipal wastewater stream. Municipal wastewater was scalped from a local wastewater main and blended with the EDR concentrate (EDR was simultaneously pilot tested) prior to treatment in the fixed-bed bioreactor. The objectives of the project were to demonstrate sustained perchlorate removal to below detection, determine % blend and empty-bed contact time requirements, evaluate process robustness with respect to system upsets and seasonal temperature changes, determine the optimal biogrowth support medium (2 GACs and 1 plastic media were tested), and develop preliminary designs and cost estimates.

The data showed that using and empty-bed contact time of 10 minutes and a 1:1.5, wastewater flow to EDR concentrate flow blend ratio, sustained perchlorate removal to below detection could be achieved in the fixed-bed bioreactor. Testing also showed that the system was robust with respect to process upsets and that GAC was the optimal biogrowth support media. Preliminary designs and cost estimates were developed for the full-scale implementation of this process at the Magna Water Company.

The U.S. Patent office has approved Carollo's patent application for BIOBROx™. U.S. Patent No. 7,318,895.