Microbes bound to a wheat bran/red wood powder/diatomaceous earth carrier were used as inoculants for a biotrickling filter (BTF) for treating gases contaminated with a mixture of benzene, toluene, and o-xylene (BTo-X). An overall removal efficiency of more than 87.9% was achieved after a start-up period of as low as 4 days. At BTo-X loading rates (LRs) below 60.0 g/m(3) h, the BTF's performance was similar for EBRTs of 90, 60, 45 and 30 s with an elimination capacity (EC) almost approaching the LR: stable REs above 91.3% for benzene and toluene and above 82.8% for o-xylene were achieved. A maximum EC of 97.7 g/m(3) h was obtained at inlet load of 146.4 g/m(3) h. The mass ratio of carbon dioxide produced to the BTo-X removed was approximately 2.62, which confirmed complete degradation of BTo-X. The results demonstrate that microbes bound to a solid carrier can be an alternative to traditional liquid inoculums applied in BTFs and highlight their potential applicability to BTF technologies. (c) 2010 Elsevier Ltd. All rights reserved.