Carbon dioxide capture using Escherichia coli expressing carbonic anhydrase in a foam bioreactor

ABSTRACT

The present study reports CO₂ capture and conversion to bicarbonate using Escherichia coli expressing carbonic anhydrase (CA) on its cell surface in a novel foam bioreactor. The very large gas–liquid interfacial area in the foam bioreactor promoted rapid CO₂ absorption while the CO₂ in the aqueous phase was subsequently converted to bicarbonate ions by the CA. CO₂ gas removal in air was investigated at various conditions such as gas velocity, cell density and CO₂ inlet concentration. Regimes for kinetic and mass transfer limitations were defined. Very high removal rates of CO₂ were observed: 9570 g CO₂ m⁻³ _bioreactor h⁻¹ and a CO₂ removal efficiency of 93% at 4% inlet CO₂ when the gas retention time was 24 s, and cell concentration was 4 g_dwL⁻¹. These performances are superior to earlier reports of experimental bioreactors using CA for CO₂ capture. Overall, this bioreactor system has significant potential as an alternative CO₂ capture technology.

KEYWORDS:

• Carbon capture
• carbonic anhydrase
• whole cell biocatalyst
• surface-displaying bacteria
• foam bioreactor

Disclosure statement

No potential conflict of interest was reported by the authors.

Funding information

This work was supported by U.S. Department of Agriculture [grant number HAW05024-H].