Kinetic characterization of toluene biodegradation by Rhodo coccus erythropolis: Towards a rationale for microflora enhancement in bioreactors devoted to air treatment

The kinetic characterization of microorganisms degrading volatile organic compounds (VOCs) is difficult due to the low substrate concentration prevailing in these processes. In this work, a simple, accurate and easy-to-implement methodology was proposed to perform the kinetic characterization of VOC-degrading microorganisms. The methodology was applied to Rhodococcus erythropolis using toluene as a model VOC. Besides the assessment of traditional kinetic parameters such as the maximum specific growth rate (mu(max)), substrate half-saturation (K-s) and substrate inhibition (K-1), the methodology here proposed yielded the 46 kinetic parameter, which indicates the relative relevance of the biomass growth rate and bacterial density on the VOC mineralization performance. R. erythropolis exhibited K-s, K-1 and mu(max) values of 0.39 g m(-3), 54 g m(-3) and 0.21 h(-1), respectively. The potential of this microorganism (supporting extremely low K-s and high K-1 values) for boosting the performance of bioreactors treating low toluene concentrations was highlighted. Furthermore, alpha/beta ratios of similar to 50 to similar to 500 were recorded at initial toluene gas concentrations of 1.5-5.2 g m(-3), respectively. These alpha/beta ratios indicated that toluene mineralization under the working conditions was mainly related to the biomass growth rather than to the biomass concentration. (C) 2014 Elsevier B.V. All rights reserved.