An advanced air-treatment system that uses a mélange of microbes to treat hazardous air emissions is the direct consequence of ONR-sponsored research at a small New Jersey company. The emissions include odors from oily bilge holding tanks and pollutants from point sources such as paint spray booths.
The efficient, affordable system developed by Envirogen, Inc., of Lawrenceville, N.J., relies on the action of naturally occurring microorganisms to metabolize air pollutants into harmless byproducts. The microbes grow as a biofilm on synthetic packing material contained in a tall column that resembles a ship's smoke stack. Untreated air enters the column at the top and flows downward through the packing material along with recirculating water. The microbes degrade and destroy the contaminants as they pass over the biofilm. The recirculating water allows for optimal control of pH, nutrient levels, and biofilm thickness.
Known as a biotrickling filter, this treatment method safely and efficiently destroys volatile organic compounds (VOCs), hazardous air pollutants (HAPs), and odor causing chemicals. Biotrickling filters offer more cost-effective treatment options than standard biofilters for compounds with low-water solubilities or slow degradation rates. The technology also is an effective treatment option for many biodegradable chlorinated compounds.
A prototype system installed at the Naval Air Station-North Island in San Diego, Calif., reduced HAP emissions from aircraft painting operations by up to 95 percent over a four month period. A permanently installed unit at the same site now reduces pollution from the Industrial Wastewater Treatment Facility and Oil Recovery Plant. In other tests, the system removed up to 99 percent of the odiferous compounds hydrogen sulfide and methyl mercaptan.
Commercial applications for the biotrickling system include emission control for automobile painting, furniture finishing, chemical and plastics processing, and industrial and municipal water treatment systems. Biotrickling filter systems can be supplied in standard or semi-custom sizes, with instrumentation and control packages provided. Envirogen developed the biotrickling filter technology under a Navy Small Business Innovation Research contract. ONR administers the Department of the Navy's SBIR Program to give small companies the opportunity to become part of the national technology base that serves both the military and private sectors.