Fermentor
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Main > Food and Agriculture > Controlled-environment growing
A fermentor or fermentation chamber is a type of bioreactor for containing and controlling fermenter microorganisms. Fermentation is an important economical route to important raw materials (ethanol, lactic acid) and fermented foods. A fermenter must control temperature and keep the chamber anaerobic and free of oxygen to optimize conditions for desired microbial fermentation. Fermentation is a basic and highly developed art and also pursued by hobbyists. Necessary public information is available to create an economical and high performance OSE version to complete certain product ecologies.
Fermentation
Fermentation is a way for microorganisms to continue metabolism when there is no exogenous electron acceptor. Microorganisms are forced to use an electron acceptor that is available endogenously, usually an organic compound. The organism gains high energy electrons by converting the molecule to lower energy forms by catalyzing the breakdown of oxygen functional groups to a lower redox state. The breakup of sugars into a large amount of modified small organic molecules such as ethanol, lactic acid, or acetic acid is useful to an OSE context for its ability to process agricultural feedstocks into desirable materials and foods. Fermentation is carried out by yeast and bacteria, in liquid and anaerobic solids. Silage is an example of solid state fermentation and fermentors are used for solution state fermentation.
OSE fermentor
Prototype 1
The fermentor should be designed to control the conditions necessary to raise any nonphototrophic microorgansism (see Photobioreactor). An initial prototype should be built to control the conditions for lactic acid and ethanol fermenters. Anaerobic and aseptic conditions must be maintained by being sealed to the outside. Initial designs will be for batch production but allow for configuration for continuous runs with proper attachments. Gas hookups will allow gas exchange with the atmosphere or injection of gas hookups. Top or side ports would allow the removal of broth and addition of substrates. The fermentor should be built in a conical shape to allow easy draining and the settling of particulate matter, an agitator should be located above the bottom port.
Advanced features
1. Configurable to allow different component hookup such as aeration, dialysis and inputs allowing continuous run 2. pH measurement with automatic base addition 3. Sensors for temperature, dissolved oxygen, liquid level sensor, nutrient density and cell density (via turbidity). 4. Growth programs
OSE fermentor specifications
- Ability to maintain anaerobic conditions, while removing product and adding substrate
- Internal dimensions
- Internal volume
- Conical shape with outlet port at lowest point
- Material - Nonreactive stainless steel
Design rationale
An OSE fermentor will be designed for small scale production of desired chemical material rich broth from agricultural materials. The design will incorporate key features found in industrial and laboratory fermentors including agitation, level sensors, removal of media and addition of feed during the run for continuous operation, and pH sensing and automatic base addition to maintain an optimal internal environment. Agitation is necessary to maintain optimal mixing of the feedstock with the microorganisms and will be controllable in the range of 1-200 rpm. A level sensor is necessary to accurately control the removal of spent broth and the addition of feed for continuous operation. An electronic pH sensor will be necessary to measure this aspect of internal environment and control the acidification of the environment through the addition of a base. A turbidity sensor, that measures the absorbance at a specific adjustable wavelength (~600 nm), will be used quanitify cell density and maintain optimal density for continuous run operations.