Treatment of Gasoline Residuals by Granular Activated Carbon Based Biological Filtration∗

Abstract

Abstract Most biofilters use compost as the microorganism support medium. This study investigated the use of granular activated carbon (GAC) as a support medium. Its high adsorptive capacity is a feature that makes GAC a potentially good biofilter medium. A bench‐scale column provided the experimental results presented in this paper. Gasoline vapors were the contaminant treated. The GAC was seeded with microorganisms and nutrients, and the system was operated using prehumidification of the incoming gas stream only. The history of treatment efficiency indicated initial adsorption provided high percentages of removal. However, once the adsorption capacity was saturated, the treatment efficiency dropped dramatically. Later, biological activity increased to the point where effective treatment was possible. The main obstacle to effective treatment was the slow growth of biomass in the lower portions of the column. The average and maximum elimination capacities of the biofilter were high compared to published bench scale results for compost biofilters. Elimination rates were proportional to pollutant loading. Plate counts show that both bacterial and fungal numbers increased as the column operated.