[Removal of pyridine using suspended and attached growing bacterium of Paracoccus denitrificans W12].

In this study, a pyridine-degrading bacterium, Paracoccus denitrifican W12, was isolated. It was cultivated to grow on the surface of activated bamboo charcoal (ABC) particles so that the ABC turned into biological activated bamboo charcoal (BABC) covered with biofilm of the W12. Free cells of the W12 and the BABC were separately tested in removing pyridine from aqueous solution. The results showed that 0.31 g x L(-1) suspended growing-W12 completely degraded 48.70-1399 mg x L(-1) of pyridine within 26.5-48.9 h, while the BABC (attached growing-W12) degraded pyridine much more efficiently due to the combination of biodegradation and adsorption. When the dosage of BABC was 10.0 g x L(-1) at the temperature of 35 degrees C, 692.2 mg x L(-1) of pyridine was decreased by 52% in the first 3.6 h mainly by adsorption, then was totally removed within 23.7 h mainly by biodegradation. Increasing the dosage of BABC or batch of treatment promoted the efficiency of pyridine removal remarkably. The synergistic mechanism of BABC removing pyridine from aqueous solution was further discussed on the basis of its microstructure.