Solid-Liquid Two Phase Partitioning Bioreactors as a tool for xenobiotic biodegradation: case study of 4-nitrophenol

In this paper the performance of two phase liquid-solid systems applied to the removal of xenobiotics was investigated. 4-nitrophenol, a typical representative of substituted phenols, was chosen as the target compound. Three polymers, a polyether-ester copolymer Hytrel 8206, a poly-caprolactone polyester Tone P797 and a polyethylenevinyl acetate copolymer Elvax were utilized in batch kinetic tests. The best performance was obtained with Hytrel, and this polymer was also employed as the partitioning phase in a lab scale sequencing batch reactor. In all cases in the two phase systems, even if operated with a very low polymer content (similar to 5%), the biomass was exposed to 4-nitropheol concentrations that are significantly lower if compared to the one-phase aqueous system with consequent drastic reduction of the toxic effect of 4-nitrophenol, and of the reaction times. A process model was also set up and applied to analyze the performance of the system in different operating conditions.