Petroleum Environmental Research Forum Field Study on Biofilters for Control of Volatile Hydrocarbons

A field study on the treatment of volatile petroleum hydrocarbons (PHC) by biofiltration was conducted by the Petroleum Environmental Research Forum (PERF) between 1992 and 1994. Its objective was to assess the technical, regulatory, and economic feasibility of biofiltration for off-gases from petroleum processing and soil remediation equipment. It involved three small-scale biofilters provided by U.S. vendors, treating off-gas from two soil vapor extraction sites and a source of refinery wastewater. Comprehensive monitoring of biofilter operating parameters and performance was conducted. The results suggest that biofilters remove major petroleum hydrocarbon classes to strongly varying degrees. Typically more than 95% of aromatic compounds such as benzene, and odorous reduced sulfur compounds can be removed at residence times of one minute or less, while removal of more than 70% of light aliphatics will require residence times of several minutes, and will thus require correspondingly large filter volumes and higher capital expenditure. This indicates that off-gas composition and regulatory control objective will largely determine whether biofiltration is economically feasible for a given off-gas stream. The high percentage removal of aromatic hazardous air pollutants (HAP) and odors can generally be accomplished at comparatively short residence times (one minute or less) while the need for high-percentage removal, particularly of light aliphatics (