Comparative investigation of fine bubble and macrobubble aeration on gas utility and biotransformation productivity

Abstract

The sufficient provision of oxygen is mandatory for enzymatic oxidations in aqueous solution, however, in process optimization this still is a bottleneck that cannot be overcome with the established methods of macrobubble aeration. Providing higher mass transfer performance through microbubble aerators, inefficient aeration can be overcome or improved. Investigating the mass transport performance in a model protein solution, the microbubble aeration results in higher k L a values related to the applied airstream in comparison with macrobubble aeration. Comparing the aerators at identical k L a of 160 and 60 1/h, the microbubble aeration is resulting in 25 and 44 times enhanced gas utility compared with aeration with macrobubbles. To prove the feasibility of microbubbles in biocatalysis, the productivity of a glucose oxidase catalyzed biotransformation is compared with macrobubble aeration as well as the gas-saving potential. In contrast to the expectation that the same productivities are achieved at identically applied k L a, microbubble aeration increased the gluconic acid productivity by 32% and resulted in 41.6 times higher oxygen utilization. The observed advantages of microbubble aeration are based on the large volume-specific interfacial area combined with a prolonged residence time, which results in a high mass transfer performance, less enzyme deactivation by foam formation, and reduced gas consumption. This makes microbubble aerators favorable for application in biocatalysis.

Field trials to determine the efficacy of aerators to mitigate hypoxia in inland waterways

“…The pump supersaturated DO in the treated pond, making DO concentration significantly higher than the control, without raising TGP. The advantage of smaller bubbles over bubbles with a diameter of ,1 mm is that they have a much larger surface-area to volume ratio (more than 95% of the of gas molecules in the suspension can exist in the dissolved phase; Kim et al 2020) and they are more stable, remaining in the water column for far longer (Thomas et al 2021). Because of this, they are more efficient at increasing the DO concentration of hypoxic water and do so in a more energy-efficient way (Ovezea 2009).…”

Review of options for creating and maintaining oxygen refuges for fish during destratification-driven hypoxia in rivers

“…There is an industry standard (ISO 20480-1, see https://www.iso.org/obp/ui/#iso:std:iso:20480:-1:ed-1:v1:en) used to describe the size of bubbles, and they can range in decreasing size from millimetre to sub-millimetre (,1 mm) to microbubbles (,100 mm) to ultrafine bubbles (,1 mm). The advantage of ultrafine over millimetre-sized bubbles is that they have a much larger surface area to volume ratio, more than 95% of the of gas molecules in the suspension can exist in the dissolved phase (Kim et al 2020) and they are more stable, remaining in the water column for longer (Thomas et al 2021). They are therefore more efficient at increasing the DO concentration of hypoxic water and do so in a more energy-efficient way (Ovezea 2009).…”

Monitoring and control of the release of soluble O2 from H2O2 inside porous enzyme carrier for O2 supply to an immobilized d‐amino acid oxidase

“…Fundamental problem of biochemical engineering of these reactions is to supply the O 2 substrate in a way that meets the demands of conversion efficiency and enzyme stability, both in suitable balance Dong et al, 2018;Toftgaard Pedersen et al, 2015;Woodley, 2019). Commonly, the O 2 is delivered from gas (air, pure oxygen) entrained into the bulk liquid Garcia-Ochoa & Gomez, 2009;Lindeque & Woodley, 2020;Solé et al, 2019;Thomas et al, 2021;Tomaszewski et al, 2014;Van Hecke et al, 2011).…”