In bioreactor systems, achieving optimal mass transfer of gases such as oxygen or carbon dioxide can be challenging. This is particularly true for oxygen, which is poorly soluble in water and even less so in cell culture and fermentation broths. While agitation is commonly used to mix nutrients and ensure homogeneity of the cell culture or fermentation, there are limits to agitation speed due to high power consumption and potential damage to organisms resulting from excessive tip speed.
Agitation alone is insufficient for achieving adequate mass transfer. However, by incorporating a porous metal sparger, mass transfer rates can be significantly increased in this type of equipment. Optimal mass transfer rates can be accomplished by introducing gases into stirred or unstirred reactor vessels via millions of small bubbles, which expands the gas-to-liquid contact surfaces.
