earticle

영어

Two-phase partitioning bioreactors (TPPB) have attracted attention as an alternative technology for the treatment of gaseous contaminants because they have the capacity to treat high concentrations of Volatile Organic Compounds (VOCs). In this study, a strategic approach for the design of TPPBs has been formulated using, as a basis, a re-evaluation of extensive literature data available for the degradation of benzene by Achromobacter xylosoxidans Y234 in TPPBs with n-hexadecane as the partitioning phase. Our analysis began with an evaluation of the role of biomass in TPPBs given the unique characteristic of a biological steady state seen in TPPBs over extended periods of operation with continuous VOC feeding. By using a previously measured cellular maintenance coefficient, we have now predicted the mass of biocatalyst at biological steady state required for the satisfactory treatment of benzene as a function of its loading rate. Furthermore, by calculating the total oxygen transfer rate into a TPPB as a function of operating conditions (also related to the biomass level at biological steady state), we have subsequently determined the theoretical maximum benzene elimination rate that can be achieved without oxygen limitation under various agitation and aeration rates. The impacts of varying the phase volume ratio (organic:aqueous), aeration rate, and oxygen partition coefficient between the organic and aqueous phases were also examined, with the phase volume ratio being identified as a key parameter in both TPPB design and operation. The effect of the volume ratio on the mass transfer rate of benzene into the TPPB was also evaluated, and it was determined that TPPB performance can also be strongly influenced by the Henry’s law constant or solubility of a contaminant in water. Finally, we have integrated the elements of this analysis into a set of heuristic criteria that can serve as a set of guidelines for the design of TPPB systems for future VOC treatment applications.