Gaseous o-Xylene Biodegradation in Two-Liquid Phase Airlift Bioreactor and Biotrickling Filter Configurations

Biotrickling filter (BTF) applications in two-liquid phase bioreactors (TLPB) are limited by the lack of agitation, ozone clogging in the long term and a further promotion in mass transfer. Versus a two-liquid phase BTF with silicone oil as a non-aqueous phase, a two-liquid phase airlift bioreactor (ALR) was developed to remove gaseous o-xylene. A higher elimination capacity of 26% was obtained for the two-liquid phase ALR (92 g·m^-3·h^-1, removal efficiency of 91%) versus the two-liquid phase BTF. Removal efficiency of the two-liquid phase ALR was constant and above 90% regardless of the inlet concentration. More complete removal of o-xylene was observed for the two-liquid phase ALR under both steady state and shock-load conditions. Therefore, sufficient mixing is essential to the TLPBs for the removal of hydrophobic VOCs. However, microbial diversity in the two-liquid phase ALR was not richer than that of the two-liquid phase BTF. The dominant microbial community was Comamonas in the two-liquid phase ALR, Chitinophagaceae in the two-liquid phase BTF.