Biodegradation of BTX Vapors In a Compost Medium Biofilter

Removal of benzene, toluene, and xylenes (BTX) from waste gases was studied in a 50-L laboratory-scale biofilter (25.2 cm I.D. and 100 cm H). A commercial blend of composted chicken manure and peat moss was used as the filter bed. The composted organic material was selected due to its relatively high microbial diversity and for its nutritive value (i.e. presence of N-sources and essential minerals). Three sets of experiments were carried through by changing the inlet gas concentration (500 mg m-3 to 6000 mg m”), the superficial gas velocity (9.6 m h-l, 24.1 m h-l and 36.1 m hl), the gas flow direction (upand downwards), and by controlling the moisture of the filter bed, for a total duration of 157 days. The biofilter was operated at a BTX inlet gas concentration as high as 5721 mg m-3 and showed a removal efficiency of 97 percent. The maximum elimination capacity (EC,,,) of the compost filter bed was 108 g BTX m-3 h-I. Despite these excellent results, the biofiltration process exhibited some operational problems among which were the drying out of the filter bed and the moisture control.