Advances in micro- and nano bubbles technology for application in biochemical processes

Poor mass transfer in gas–liquid systems is still a major bottleneck in many biological processes which limits effective bioconversions. Nano bubble technology (NBT) is an emerging platform which offers an immense boost in several biochemical processes. Tailored application of micro and nanobubbles (MNBs) with precise tuning with gas types and dosing rates were important for biological growth enhancement as well as growth control. From recent studies, nano gas bubbles with a diameter <200 nm was promising in the interface of gas–liquid mixing systems to improve gaseous mass-transfer and associated bioprocessing. Likewise, bubbles in micro range also showed improvement depending on size, however application of nanoparticle found promising in their stabilization. Typically, nano size gas bubbles showed lifespan over a month and offered 2–30-folds higher gas solubility depending on the gas in the aqueous system. Nano bubbles in water can persist for longer duration and privileged with adequate dissolved gases hence could promote better growth and thereby productivity of microbes. At present, there is no comprehensive review published on NBT covering its main focus on bioprocess enhancement. In this review, we aimed to provide recent updates on versatile NBT for its present role as well as potential and emerging scope in various application areas to improve the efficiency of biological processes towards better bioprocessing, economic and societal benefits.