Removal of xylene by a mixed culture of Pseudomonas sp. NBM21 and Rhodococcus sp. BTO62 in biofilter

Xylene (a mixture of o-, m-, p-xylenes and ethylbenzene) gas removal was conducted in the a biofilter inoculated with a mixture of the m- and p-xylene-degraders, Pseudomonas sp. NBM21 and an o-xylene degrader, Rhodococcus sp. BTO62 under non-sterile conditions at 20 °C. Elimination capacities of o-, m-, and p-xylenes obtained were 180 g/m3/h at 20 °C and 100 g/m3/h at 10 °C, which were significantly higher than the 60–78 g/m3/h of previously reported biofilters, indicating that the two bacteria inoculated exhibited an almost total ability to remove xylene although only present in low numbers in the biofilter. In the sterile biofilter, carbon mass balance showed that 11.6% of the removed xylene was converted to cell mass. Among the xylene components, o-xylene was the most resistant to microbial degradation in spite of the low component ratio.