According to Robert Stark, south region vice president for Envirogen, this project shows how FBR can be a reliable and environmentally sustainable solution to groundwater remediation needs. “This innovative ‘green’ technology continues to distinguish itself as the best answer to heavily perchlorate-laden groundwater in both remediation and drinking water applications.”
The 1.2 million gallons per day (MGD) capacity system will replace a smaller biological-based system in operation since 2006. It will be a custom configuration to reduce influent concentrations of perchlorate to non-detectable levels prior to surface discharge. The company, while targeting perchlorate as the primary contaminant, will also remove both chlorate and nitrate with the same process. Perchlorate is a highly soluble anion that is used in the manufacture of solid rocket propellant, fireworks, road flares, explosives and other products.
The FBR system is a fixed-film bioreactor in which biological media is suspended, or fluidised, within the reactor vessel by the upward flow of water through the system. The suspended media provides a large surface area for microbial growth and allows a biomass density several times greater than that of other bioreactor designs under similar loading conditions. Microorganisms in the reactor completely destroy influent perchlorate and other targeted contaminants under anoxic conditions, without generating hazardous waste by-products.
The new system being designed and built for AMPAC by Envirogen will consist of three FBRs and an H-120 biofilter for odour control. The facility will remove up to 500 parts per million (ppm) of perchlorate in the groundwater to non-detectable levels and, depending on the load, treat up to 800 gallons per minute (gpm).
“The technology’s flexibility to handle multiple constituents and varying flow characteristics also bodes well for its potential to treat other significant emerging contaminants such as selenium, hexavalent chromium or chlorinated solvents,” said Stark.
The new treatment system is currently still in the design phase and is scheduled for start-up in December 2011.