BIOBROx® Pilot Testing

Magna Water District, 
Utah

BIOBROx® Pilot Testing

Project Highlights: 
  • Carollo Engineers has developed a novel approach (BIOBROx®) to treating oxidant-laden residuals that involves blending the residual stream with scalped municipal wastewater, followed by treatment in a fixed-bed.
  • Process eliminates the target oxidant from the residuals stream prior to sewer discharge or reuse application.
  • Carollo Engineers designed and built a 3.75-mgd BIOBROx® facility for Magna Water District, Utah.
BIOBROx
Carollo and the Magna Water District completed to applied research studies to evaluate the efficacy of the BIOBROx® system for removing perchlorate from membrane concentrate.

Introduction

Carollo developed BIOBROx® in conjunction with a project focused on solving real-world challenges for the Magna Water District, Utah (Magna). Magna serves potable water to approximately 28,000 customers near Salt Lake City, Utah. This water supply includes groundwater impacted by perchlorate, arsenic, and TDS.

In 1999-2000, Carollo conducted a six-month pilot study showing that, due to the presence of high silica and sulfate levels in the groundwater, EDR would be the most feasible treatment alternative for Magna. EDR is a separation-based process in which an electrical potential drives charged species (e.g., perchlorate, arsenic, TDS) across ion exchange membranes, thereby removing them from the raw water.

EDR generates a contaminant concentrated residual stream that, under current USEPA regulations, could be discharged to the sewer system. However, Magna, in partnership with the local industry responsible for the original perchlorate contamination, opted to seek a method that would remove perchlorate from the brine stream prior to sewer discharge, thereby eliminating future environmental contamination.

Pilot-Scale Testing

The USEPA funded a sevenmonth pilot study at Magna’s Barton Well Field in 2004-05 to demonstrate the efficacy of the BIOBROx® process for removing perchlorate from an EDR concentrate stream. An EDR pilot plant was operated to remove perchlorate, arsenic, and TDS from groundwater, and the resulting concentrate stream was blended with scalped municipal wastewater and treated in a pilot-scale fixed-bed bioreactor. The data showed that using an EBCT of 10 minutes and a 1.5:1 wastewater flow to EDR concentrate flow blend ratio, the fixed-bed bioreactor achieved sustained perchlorate removal to below detection while demonstrating 98 percent, 65 percent, and 84 percent removal of influent nitrate, biochemical oxygen demand, and total suspended solids, respectively.

The associated required reactor volume would be a small fraction of the volume required by “conventional” biological residuals treatment systems, and no consumables would be required. Testing also showed that the system was robust with respect to process upsets and seasonal temperature variation.

Full-Scale Facility

Based on the success of the pilot-scale study, Magna and Carollo Engineers designed and built a 3.75-mgd BIOBROx® facility. The facility was started in 2009 and performance data are now being collected.

Conclusions

The need for long residence times, specialized microbial inocula, and high concentrations of exogenous substrate limit the applicability of existing processes used to biologically stabilize concentrated oxidant residuals. This bench- and pilot-scale work has shown that BIOBROx® provides an efficient alternative for post-treatment of separation-based oxidant removal processes, such as EDR, IX, or RO.