Degradation pathway and kinetic analysis for p-xylene removal by a novel Pandoraea sp. strain WL1 and its application in a biotrickling filter.

In this study, a novel Pandoraea sp. strain WL1 capable of mineralizing p-xylene as sole carbon and energy source was isolated from the activated sludge of a pharmaceutical wastewater treatment plant. A nearly complete degradation of 16.6∼99.4 mg L(-1)p-xylene in the liquid-phase was achieved within 6∼18 h accompanied by 15.9∼56.3 mg dry cell weight (DCW)L(-1) for bacterial growth. A complete pathway for p-xylene degradation by strain WL1 was presented through identification of a major intermediate (p-toluic acid) and final products (2.193 gCO2 gp-xylene(-1) of CO₂ production and 0.215 g DCW gp-xylene(-1) of bacterial yield). Kinetics of bacterial growth and p-xylene degradation were evaluated using Haldane-Andrews model and pseudo first-order model, respectively. Furthermore, a biotrickling filter (BTF) was employed to evaluate the application of strain WL1 on the removal of gas-phase p-xylene under gas flow rates of 0.41∼1.98 m(3)h(-1) for inlet loading rates of 5∼248 gm(-3)h(-1). The BTF inoculated with strain WL1 proved to be robust against fluctuations of gas flow rates and inlet p-xylene concentrations. All the results obtained highlight the potential of strain WL1 for the treatment of p-xylene.