The demonstration, which ran through the end of March, was initiated and implemented by the Southeastern Technology Center of Augusta, Georgia. The center has a cooperative agreement with the U.S. Department of Energy at the Savannah River Site to transfer to the private sector DOE-developed environmental technologies that show high potential for rapid commercialization. STC contracted with regional industry participants to demonstrate how the biofilter could solve a local environmental problem and to encourage industry to use the technology. Delphinus Engineering in Aiken, South Carolina provided engineering design and technical and management services for the project. Augusta Fiberglass Coatings agreed to serve as the industrial site where the technology was tested to determine its efficiency and cost-effectiveness as an air pollution control technology. Westinghouse Savannah River Company also collaborated on this project by providing technical assistance and laboratory services.

Biofiltration can be used to reduce the concentration of volatile organic compounds in soil, ground water, and air. The U.S. Department of Energy's Office of Science and Technology has supported the concept of biofiltration since 1992 when EG&G Biofiltration signed a $1 million cost-shared cooperative research and development agreement with OST. The CRADA was used to develop a bioreactor for degrading VOCs found in soils and ground water. Today, EG&G Biofiltration, the marketing arm of EG&G Rotron, markets its trademarked Biocube as an odor control technology at wastewater and industrial facilities.

Researchers at DOE's national laboratories have continued their investigation into biofiltration applications and other biological processes. In 1995, Pacific Northwest National Laboratory researchers successfully applied in situ bioremediation by injecting nutrients underground to stimulate indigenous microbes to biodegrade carbon tetrachloride in ground water (see April 1996 Initiatives). These results stimulated the idea to enhance biofiltration processes by using nutrient injection.

Jim Kastner began researching biofiltration while at Idaho National Engineering and Environmental Laboratory. Currently, Kastner is with Westinghouse Savannah River Company and is investigating how microorganisms in biofilters can be dosed with nutrients so they'll continue to biodegrade contaminants.

Kastner said, "Biofiltration has been used in Europe for 10 years or so and has been used for three or four years in the states. It's currently being used by General Electric, Monsanto, and Eastman Kodak; and other companies are also beginning to use biofiltration as a method of controlling air pollution. The demonstration at Augusta Fiberglass Coatings will determine if biofiltration will abate styrene emissions from a fiberglass manufacturing facility. Literature documents that chicken compost has potential as a biofiltering matrix, and its use is a cheap alternative to current air emission control devices."

The biofilter at Augusta Fiberglass Coatings is based on an air pollution control technology that works by passing VOC-contaminated air through one or more beds of a fixed, porous medium. The medium provides a surface for microbial attachment and also provides nutrients to the microbes. Microorganisms in the biofilter degrade gas-phase VOCs to carbon dioxide and water.

In the chicken compost biofilter at AFC, an air pump and blower exhausts air from the Pipe Assembling Building through polyvinyl chloride piping to the biofilter tank, which stands on a reinforced concrete foundation outside the PAB. Based on the results of a treatability study, Delphinus Engineering determined that chicken compost and granular activated carbon in a 2:1 ratio was the medium that offered the best removal efficiency for styrene. The biofilter system also includes a propane-fired boiler that heats and humidifies the incoming air stream. Spray nozzles in the biofilter tank add water to the compost and can also provide nutrients to the microbes.

The biofilter as constructed and operated at AFC proved capable of removing low levels of styrene. Results show the biofilter reduced styrene levels from 200 parts per million to below 7 parts per million. Methylene chloride and methyl ethyl ketone, two other gases resulting from fiberglass production, are also amenable to biofiltration. The biofilter is an inexpensive method of removing these gases.

Mature technologies that have proven effective in reducing VOCs in air (e.g., vapor scrubbing, thermal oxidation, catalytic oxidation, and carbon adsorption) are more costly than biofiltration. Data from the AFC field test support cost analyses found in literature showing that biotreatment of industrial waste gases containing VOCs is 2 to 10 times less expensive than thermal oxidation or catalytic oxidation, 10 to 40 times less expensive than carbon adsorption, and 4 times less expensive than traditional scrubbing. Another consideration is that vapor scrubbing and carbon adsorption require further processing to oxidize VOCs to carbon dioxide and water.

The demonstration proved successful in more ways than just verifying that the biofilter could stop styrene from entering the environment. The demonstration also provided economic stimulus to the community and the participating companies. The experiment worked so well that AFC decided to keep its full-scale unit to control styrene. The unit's instrumentation will be upgraded to ensure long-term reliability. AFC is now working with state regulators to obtain a permit for its continued operation.

Mike Ramay of Delphinus said the demonstration was a learning experience for his company. Although Delphinus was familiar with the biofiltration concept before the demonstration, the company learned how to apply the concept by being "joined at the hip with STC." By collaborating with STC on the demonstration, Delphinus learned enough to begin marketing a new biofilter product line. Delphinus is now seeking manpower for designing specific biofilter applications and assembling the units. AFC has agreed to manufacture the fiberglass tanks for the biofilter systems Delphinus sells. The technology transfer set in motion by the contracts between STC and Delphinus and between STC and AFC is filtering down to create jobs in the local community.