Toluene biodegradation from synthetic waste gas by aerobic denitrification using nitrate as an electron acceptor in a biotrickling filter (BTF) was investigated. Toluene removal efficiency achieved 92.3% in 105 days of operation. Pseudomonas, Paracoccus, Flavobacterium, SM1A02, Acinetobacter, Blastocatella, Moheibacter, Chlamydiales, Rhodobacter, and Ottowia were dominant toluene-degrading genus. Bradyrhizobium, Comamonas, Cupriavidus, Pseudomonas, Pseuoxanthomonas, and Ralstonia simultaneously had the ability to participate the process of toluene biodegradation and denitrification. BTF used nitrate or oxygen as electron acceptor, toluene as electron donor, and thereby redox between toluene and nitrate was formed, to realize toluene oxidation. BTF was capable of toluene oxidation by denitrification. These results show that the aerobic denitrifying BTF is achievable and open new possibilities for applying the BTF to the removal of volatile organic compounds. [ABSTRACT FROM AUTHOR]