Strategies to overcome mass transfer limitations of hydrogen during anaerobic gaseous fermentations: A comprehensive review.

Fermentation of gaseous substrates such as carbon dioxide (CO) has emerged as a sustainable approach for transforming greenhouse gas emissions into renewable fuels and biochemicals. CO fermentations are catalyzed by hydrogenotrophic methanogens and homoacetogens, these anaerobic microorganisms selectively reduce CO using hydrogen (H) as electron donor. However, H possesses low solubility in liquid media leading to slow mass transport, limiting the reaction rates of CO reduction. Solving the problems of mass transport of H could boost the advance of technologies for valorizing industrial CO-rich streams, like biogas or syngas. The application could further be extended to combustion flue gases or even atmospheric CO. In this work, an overview of strategies for overcoming H mass transport limitations during methanogenic and acetogenic fermentation of H and CO is presented. The potential for using these strategies in future full-scale facilities and the knowledge gaps for these applications are discussed in detail.