03-11-2009, 04:10 PM
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ABSTRACT
Bio-technologies have evolved into viable treatment technologies not only for odorouscompounds, but more complicated mixed airstreams that include volatile organiccompounds (VOCs). Digestion of compounds such as benzene, toluene, ethylbenzeneand xylene (BTEX) have been of particular interest in petroleum processes and clean-upprojects as an alternative treatment to incineration technologies.A bio-oxidation treatment process, bioremediation, has been successfully implemented ina variety of projects and conditions. Taken one step further, a Ëœbio-oxidizerâ„¢ controls theenvironmental factors that affect bioremediation technology success. The bio-oxidizersare enclosed with automated controls that provide consistent air flow to maintain aerobicconditions, spraying mechanisms for humidification, watering systems to providenecessary moisture content. All of these conditions are necessary for optimum conditionsfor the microbes. The last control factor is the substrate used for microbial growth, whichmay be inorganic, organic, or a combination of both.Bio-oxidizers, although modular in nature, are designed for specific project parameters.Each site or facility should provide the following evaluation criteria: process airflow,contaminants in the airstream, concentrations for each of the compounds, andtemperature of airstream. Other factors include: site location, utility resources, and theability to discharge a small amount of blowdown during a routine weekly maintenanceprogram. Last, and most important, the goal for the project whether itâ„¢s strictly odorcontrol or if a removal efficiency percentage is required by facility permits, governmentrequirements or worker-related safety. The more factors analyzed and determined priorto install will ensure proper vessel sizing, as well as increase performance capabilitiesand reliability of the system.A bio-oxidizer was selected as the best technology for a soil vapor extraction (SVE)remediation project in rural Oregon. The installation is located in a highly sensitiveneighborhood and the goal for the system was odor removal. Due to the close proximityof homes, the project required a quiet, low maintenance and reliable technology to treatthe off-gas vapors from the SVE system. The initial projected contaminant loadings weregrossly underestimated, and although the ultimate goal for the bio-oxidizer was odorremoval, the system continued to improve on overall hazardous pollutant removalefficiencies vented through the system.In comparison, a bio-oxidizer was installed on a glycol dehydrator at a natural gasprocessing field in Louisiana. The project goal was reduction of benzene, a hazardous airBack
--------------------------------------------------------------------------------pollutant under state requirements. The contaminant loadings for this system weremeasured in excess of 100,000ppm of total VOCs, while the BTEX portion ranged from50-80% of the total VOCs.Biological systems are extremely viable for mid-to-lower range concentrations, and caneven be sized to accommodate higher loadings by designing for longer retention times,lower airflows, and surge loading capabilities. Bio-oxidation provides a sustainablesolution to incineration-type technologies, reducing greenhouse gas production bycapturing and treating the contaminants, not creating any secondary pollutants during theprocess, and using less energy with little to no fossil fuels required to run the system.Data from the above-mentioned installations will be discussed during the presentation,along with system design parameters, how to optimize biological systems, theenvironmental benefits and the economics of bio-oxidizers
