BIOFILTRATION OF BTEX CONTAMINATED AIR STREAMS USING COMPOST-ACTIVATED CARBON FILTER MEDIA

Three laboratory-scale biofilter columns were operated for 82 days to investigate the removal of benzene, toluene, ethylbenzene, and a-xylen e (BTEX) from a waste gas stream. The columns contain a mixture of yar d waste and sludge compost as the base biofilter material. Different a mounts of granular activated carbon (GAC) are mixed with the compost i n two of the three columns to evaluate the extent to which biofilter p erformance can be enhanced. The columns displayed preferential utiliza tion of benzene followed by toluene, ethylbenzene, and o-xylene, respe ctively. Removal efficiencies of greater than or equal to 90% were ach ieved for inlet concentrations of greater than or equal to 200 ppm of each of the BTEX compounds and a gas loading rate of 17.6 m(3)/m(2) h in all columns over the period of study. During sudden increases in th e gas flow rate or the BTEX influent concentration, biofilters contain ing GAC exhibited significantly higher removal efficiencies and more s table operation than the biofilter containing only compost. (C) 1998 E lsevier Science B.V. All rights reserved.