Two-phase partitioning bioreactors: towards a new generation of high-performance biological processes for VOC and CH4 abatement

Abstract

The intense research and development conducted over the past 30 years in the field of air pollution control have increased the acceptance of biotechnologies as cost-efficient technological solutions to mitigate atmospheric pollution. Despite the low operating cost of biofilters and biotrickling filters, the limited mass transfer rates of certain key air contaminants from the gas phase to the microbial community and the perceived limited robustness of biotechnologies still make physical-chemical technologies the preferred methods for air pollution control. In this context, the addition of a non-aqueous phase to conventional bioreactors, in the so called two-phase partitioning bioreactors (TPPBs), can overcome the above mentioned limitations and trigger the consolidation of biotechnologies for the removal of odors, volatile organic contaminants (VOCs) or greenhouse gases. TPPBs have been successfully implemented in stirred tank, airlift, biofilter and biotrickling filter reactors for the removal of hydrophobic VOCs and CH 4 at unprecedentedly high removal rates. The high affinity of the non-aqueous phase for the target gas pollutant creates a new and efficient mass transfer pathway and increases process robustness compared to conventional biotechnologies. Finally, recent studies have shown that the use of hydrophobic biomass can boost the abatement performance of TPPBs by one order of magnitude.