Fermentative oxidation of butane in bubble column reactors

Abstract

Butane is an abundant side product of oil and gas production and is mostly burned for energy and heat production. The alkane monooxygenase enzyme system AlkBGT expressed in E. coli offers a robust model system with a fast butane uptake for microbial oxidation at low temperatures (25–40 °C) and pressures (1.1–1.5 bar). The process is established in a two liter bubble column under strict safety requirements obligatory for butane/air mixtures. Detailed characterization of the transport limited process regarding the relevant process parameters gassing rate / superficial velocity (0.25–1.5 L·min−1/ 0.8 – 5 cm·s−1), butane content (14–28 % v/v), pressure as well as temperature is carried out. Classical kLa-transferability is shown inside the selected process window. The determined optimum (1.5 L·min−1/ 5 cm·s−1; 1.5 bar; 35 °C and 14 % v/v) is validated and a first scale up to 5 L is approximated. The potential is discussed as a first step to a fermentative oxidation of butane on industrial scale.