Microbial treatment of a styrene-contaminated air stream in a biofilter with high elimination capacities

A styrene-utilizing mixed microbial culture was isolated and utilized in a biofilter for the biological treatment of a contaminated air stream. Biofilter media consisted of composted wood bark and yard waste. The biofilters were acclimated at 120 s residence time and further evaluated at 60 and 30 s gas residence times. The biofilters received organic loading rates of up to 350 g/m(3) h. The styrene volumetric removal rate was a function of the organic loading rate and increased with increasing loading rates. Average volumetric removal rates of 69-118 g/m(3) h observed in our studies were higher than reported values for styrene biofilters. Average styrene removal efficiencies ranged from 65% to 75% (maximum 100%). Axial analysis of styrene concentration along the column indicated that the bulk of the styrene removal occurred in the first section of the biofilter. Analyses of the media indicated that the moisture content of the first section (50-55% w/w) was significantly lower than in the second and third sections (65-70% w/w). The pressure drops across the biofilter were low due to the high concentration of large media particles. The total pressure drops were 1-3, 4-6, and 10-16 mm for the 120-, 60-, and 30-s residence time periods, respectively.