Upstream & bioreactors
A bioreactor is a transport device with microbes in it — the ceiling is set by transfer, not biology; change the regime and the binding limit moves; and the adjacent step has its own chemistry.
Ten subjects with one recurring derivation: a bioreactor is a transport device with microbes in it, and the transport, not the biology, sets the ceiling. When the substrate is a gas, the entire carbon and energy flux must cross the gas–liquid film. Density is bought with transport until waste removal, not oxygen, becomes the limit. In a photobioreactor light attenuates exponentially, so the light path is the design variable and area is the honest denominator. Solid-state fermentation removes the oxygen problem and replaces it with heat that has nowhere to go; a wave reactor is capped by what a free surface can transfer.
The second idea: change the regime and the binding limit moves. The single-use ceiling near two cubic metres is film mechanics and unbaffled mixing; a scale-down model is valid for the one parameter it was matched on; remove buoyancy and every sparged reactor stops working.
The third: the unglamorous adjacent step has its own chemistry — getting a powder into solution and into a running vessel without changing it.
Start with high cell density culture systems: its argument is the one every other reactor here re-derives for its own regime.
Articles 10
| Gas fermentation reactors When the substrate itself is a gas, the entire carbon and energy flux has to cross the gas–liquid film, and the reactor becomes a gas-contacting device with microbes in it. |
| High cell density culture systems Density is bought with transport, and above a certain point the limit stops being oxygen supply and becomes waste removal. |
| Media preparation systems Getting a powder into solution, through a filter and into a running bioreactor without changing it — three steps, each with a chemistry of its own. |
| Mini bioreactors and DoE screening A scale-down model is only valid for the one parameter it was matched on, and its usefulness is decided by what you accept mis-predicting. |
| Photobioreactors for microalgae Light is the substrate, it attenuates exponentially, and that single fact makes the light path the design variable and area the honest denominator. |
| Single-use bag bioreactors, 50 L to 2000 L The ceiling near two cubic metres is set by film mechanics and unbaffled mixing, and the qualification burden is set by what the film leaches. |
| Single-use bioprocessing Replacing steel with irradiated plastic film moves the hard problems rather than removing them: sterility becomes a supply-chain property and the vessel wall becomes a chemical participant. |
| Solid-state fermentation bioreactors Without free water the oxygen problem disappears and a harder one replaces it: metabolic heat has nowhere to go, and the only way to remove it also dries the culture. |
| Space bioeconomy Remove buoyancy and every sparged bioreactor stops working, because a bubble no longer rises; what is left is a genuinely different transport regime. |
| Wave bioreactors and seed train expansion Rocking renews the liquid surface instead of injecting bubbles: gentle, closed, and permanently capped by the transfer rate a free surface can deliver. |