Figure 1. Diagram of the single chamber bioelectrical reactor treatment of perchlorate and nitrate containing waters.

APPLICATIONS OF TECHNOLOGY:

• Remediating perchlorate and chlorate contamination in drinking water, ground water, waste streams, disposal ponds, and military inventories

ADVANTAGES:

• Low cost, low maintenance, one-step process
• No biomass or contaminated resin byproducts
• Performance comparable with current technologies
• Eliminates biofouling, corrosion, and the downstream
  addition of toxic byproducts for disinfection
• Addition of chemical electron donors unnecessary
• Avoids the challenges encountered with handling
  hydrogen in chemolithotrophic processes
• Remediates mixed wastes containing nitrate, perchlorate, and chlorate

ABSTRACT:

John Coates and Cameron Thrash of Berkeley Lab have developed a low-maintenance, chemical free perchlorate remediation system in which a cathode functions as the electron donor for microbial perchlorate reduction in the working chamber of a bioelectrical reactor. The bacteria in this bioelectrical process are maintained at constant levels, eliminating the biomass disposal costs incurred by conventional microbial reduction systems.  The invention is suitable for wellhead treatment of drinking water, ex situ treatment of contaminated ground waters, as well as in situ remediation of ground water and liquid contamination sites.

The Berkeley Lab remediation technology has been demonstrated to work with both high (ppm) and low (ppb) level perchlorate concentrations as well as with natural ground waters containing mixed wastes of perchlorate and nitrate, achieving 100% treatment efficiency in all cases and volumetric loading rates as high as 60 mg per liter of reactor volume per day.  With further development, the Berkeley Lab remediation method may exceed the performance of current technologies.

The Berkeley Lab system includes both a reductive and oxidative environment within a single chamber electrochemical cell. The cell consists of a cathodic graphite particle bed infiltrated with perchlorate-reducing bacteria, an anode, ports for inflow and outflow, and an electrical load.  The bacteria use the cathode surface as a source of electrons for perchlorate reduction.  No additional organic carbon is supplied, thus limiting propagation of the organisms while stimulating their perchlorate reducing activity. In addition to eliminating biomass disposal, the Berkeley Lab system significantly reduces downstream issues associated with traditional bioreactors, including biofouling, corrosion, and the production of trihalomethanes during disinfection of treated waters.

STATUS:

• Published Patent Application . Available for licensing or collaborative research.

FOR MORE INFORMATION:

Thrash, J.C., Van Trump, J.I., Weber, K.A., Miller, E., Achenbach, L.A., Coates, J.D., "Electrochemical Stimulation of Microbial Perchlorate Reduction," Environ. Sci. & Technolog. Published on Web 02/01/2007.

REFERENCE NUMBER: IB-2318

SEE THESE OTHER BERKELEY LAB TECHNOLOGIES IN THIS FIELD:

• Cost Effective Method for Removing Arsenic from Water IB-1742

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