Formation of Acidic and Toxic intermediates in Overloaded Ethanol Biofilters

Abstract

Three biofilters inoculated with different amounts of active biomass were used to treat air contaminated with ethanol vapors. Chemostat-grown microbial culture was added in amounts up to 2% of the weight of the granular activated carbon (GAG) support medium. The contaminant load was 156 g ethanol per m³ biofilter per hour. The inoculation eliminated the initial period of poor treatment, which has been observed in other GAG biofilters. The most heavily inoculated biofilter, however, experienced a period of process upset. Rapid ethanol consumption was associated with production of acetaldehyde, acetic acid, and ethyl acetate. The resulting pH reduction inhibited treatment. Such upset conditions can be avoided by eliminating overload conditions and maintaining the alkalinity of the support medium.