This article bioprocess engineering doran pdf multiple issues. Unsourced material may be challenged and removed. Organisms growing in bioreactors may be submerged in liquid medium or may be attached to the surface of a solid medium.
Submerged cultures may be suspended or immobilized. Suspension bioreactors can use a wider variety of organisms, since special attachment surfaces are not needed, and can operate at much larger scale than immobilized cultures. However, in a continuously operated process the organisms will be removed from the reactor with the effluent. Immobilization is a general term describing a wide variety of cell or particle attachment or entrapment. It can be applied to basically all types of biocatalysis including enzymes, cellular organelles, animal and plant cells.
Immobilization is useful for continuously operated processes, since the organisms will not be removed with the reactor effluent, but is limited in scale because the microbes are only present on the surfaces of the vessel. Under optimum conditions, the microorganisms or cells are able to perform their desired function with limited production of impurities. The temperature of the fermentation medium is maintained by a cooling jacket, coils, or both. Particularly exothermic fermentations may require the use of external heat exchangers. Nutrients may be continuously added to the fermenter, as in a fed-batch system, or may be charged into the reactor at the beginning of fermentation.
The pH of the medium is measured and adjusted with small amounts of acid or base, depending upon the fermentation. In an aerobic process, optimal oxygen transfer is sometimes the rate limiting step. Oxygen transfer is usually helped by agitation, which is also needed to mix nutrients and to keep the fermentation homogeneous. To avoid it, the bioreactor must be easily cleaned. Interior surfaces are typically made of stainless steel for easy cleaning and sanitation. Typically bioreactors are cleaned between batches, or are designed to reduce fouling as much as possible when operated continuously. A simplified continuous bioreactor that is designed for non-professionals, enables the growth of E.
These bioreactors do not rely on autoclavability, but instead rely on chemical inactivation for reuse. A laptop-sized Personal Bioreactor and Transformation station for bioengineering. Suitable for bacterial growth and culturing. In the most efficient of these systems, there is a supply of a free-flowing, chemically inert medium which acts as a receptacle for the bacteria that break down the raw sewage. Examples of these bioreactors often have separate, sequential tanks and a mechanical separator or cyclone to speed the separation of water and biosolids.