Biodegradation of a phenolic mixture in a solid-liquid two-phase partitioning bioreactor

Area of Science:

• Environmental Biotechnology
• Bioreactor Engineering
• Wastewater Treatment

Background:

• Phenolic compounds are common industrial pollutants that pose significant environmental and health risks.
• High concentrations of phenols can inhibit microbial activity, hindering biodegradation processes.
• Two-phase partitioning bioreactors (TPPB) offer a potential solution for handling toxic or inhibitory compounds.

Purpose of the Study:

• To investigate the efficacy of a solid-liquid TPPB using polymer beads (HYTREL) for degrading a mixture of phenols.
• To demonstrate the role of polymer beads in mitigating substrate inhibition during phenolic biodegradation.
• To explore the partitioning behavior of phenols and degradation intermediates within the TPPB system.

Main Methods:

• Utilized a solid-liquid TPPB with HYTREL polymer beads as the non-aqueous phase.
• Degraded a model mixture of phenol, o-cresol, and 4-chlorophenol (4CP) using a microbial consortium.
• Experimentally assessed the impact of polymer beads on biodegradation rates at varying substrate concentrations, including inhibitory levels.

Main Results:

• Polymer beads rapidly reduced high phenol concentrations (850 mg/L) to sub-inhibitory levels, facilitating subsequent complete biodegradation within 8 hours.
• Inhibition caused by very high substrate loads (1,300-2,000 mg/L) was overcome by adding polymer beads, enabling complete phenolic destruction.
• Differential partitioning of phenols between aqueous and polymer phases was observed, with the polymer also sequestering a 4CP degradation intermediate.

Conclusions:

• Solid-liquid TPPBs with polymer beads are effective for degrading inhibitory phenolic mixtures.
• The polymer sequestering phase is crucial for overcoming high substrate concentration inhibition in bioreactors.
• TPPB technology shows promise for sequestering metabolic byproducts during biosynthetic transformations.