MINI REVIEW article
Front. Environ. Eng.
Sec. Water, Waste and Wastewater Engineering
This article is part of the Research TopicHighlights on Biotechniques for Air Pollution Control and BiorefineryView all articles
Mini-review of Capillary Gas Treating Bioreactors – Opportunities and Challenges
Provisionally accepted
Norbertus J. R. Kraakman1
Andres Felipe Torres Franco2
Bruna Sampaio de Mello2
Sergio Bordel2Raquel Lebrero2Raúl Muñoz2*- 1Jacobs Engineering, Englewood, CO, United States
- 2Universidad de Valladolid, Valladolid, Spain
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Mass transfer in gas-liquid contactors requires energy input (e.g., mixing or pressure drop) and is a critical parameter for the design and application of process equipment. Efforts in the engineering of less energy-intensive reactors to enhance mass transfer rate is key in biological gas-liquid reactors treating hydrophobic gaseous compounds. Mass transfer coefficients (KLa) in capillary reactors may be between one or two orders of magnitude higher than in conventional gas-liquid contactors. In this context, environmental abatement processes typically implemented in bioscrubbers or biotrickling filters, and industrial fermentation processes using airlift or stirred tank bioreactors containing cell cultures that are mass transfer limited, could benefit from a capillary gas bioreactor configuration using macro-channel (> 1 mm internal diameter). This review discusses capillary reactors which can combine good mass transfer with relatively low pressure drop, two important factors affecting cost effectiveness for many industrial applications of biological gas treatment/processing systems.
Keywords: Capillary bioreactor, Gas treatment, mass transfer, Segmented flow, Taylor flow
Received: 09 Oct 2025; Accepted: 08 Dec 2025.
Copyright: © 2025 Kraakman, Felipe Torres Franco, Sampaio de Mello, Bordel, Lebrero and Muñoz. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) or licensor are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.
* Correspondence: Raúl Muñoz
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