Solid-Liquid two-phase partitioning bioreactors for the treatment of gas.-phase VOCs

Abstract

[Abstract] Two-Phase Partitioning Bioreactors (TPPBs) consist of a cell-containing aqueous phase and a separate, biocompatible and immiscible phase that partitions toxic substrates to the cells based on their metabolic demand and on maintaining the thermodynamic equilibrium of the system. TPPBs have traditionally used immiscible liquid organic solvents as the substrate delivery phase, however, one of the limitations of organic solvents is their potential bioavailability as substrates, and therefore these TPPB systems have generally been limited to the use of pure strains of organisms incapable of metabolizing the solvent. We have replaced the organic solvent phase in TPPBs with inert polymers (plastic beads). A TPPB employing styrene-butadiene beads as the sequestering phase was used to treat high step change loadings of BTEX in a contaminated air stream. The presence of the polymers allowed the system to effectively capture the incoming VOCs, buffer the cells from high VOC levels and release the VOCs to the cells for biodegradation. The polymer TPPB system demonstrated substantially higher performance than an aqueous phase bioscrubber and comparable performance to a solvent-aqueous TPPB. Also of great interest was the increase in oxygen transfer provided to the system by the addition of polymer beads, which have significant affinity for oxygen. The presence of polymer beads, which are biocompatible and non-bioavailable, provides a simple and effective means of enhancing the bioremediation of toxic organics present in gas streams, and potentially other phases.