Removal of gaseous dichloromethane using a solid–liquid partitioning bioreactor under gradual and stepped load increase

Silicone rubber was used as the solid non-aqueous phase of two-phase partitioning bioreactor (TPPB) for dichloromethane (DCM) removal. When the load gradually increased from 150 g m⁻³ h⁻¹–485 g m⁻³ h⁻¹ by increasing the gaseous DCM concentration, a steady elimination capacity (EC) of approximately 130 g m⁻³ h⁻¹ was achieved in one-liquid-phase completely mixed stirred tank bioreactor (CSTB), whereas the EC of TPPB was enhanced from 155 g m⁻³ h⁻¹–366 g m⁻³ h⁻¹. This result indicated that DCM removal was controlled by the biological process in CSTB and by mass transfer in TPPB. Meanwhile, the biomass decreased from 534 mg l⁻¹ to 381 mg l⁻¹ in CSTB compared with that maintained at around 580 mg l⁻¹ in TPPB due to the different resistance capabilities to DCM toxicity. Dehalogenase activity was maintained at a relatively high level under high DCM stress with the addition of silicon rubber. TPPB was shown to be more dependable in the overload from 120 g m⁻³ h⁻¹–450 g m⁻³ h⁻¹. This paper is the first to report that the crucial step in high-load pollutant removal can be converted from the biological process to mass transfer by adding solid non-aqueous phase.