fermenter and its accessories used for anaerobic fermentation

Anaerobic fermentation is carried out in specialized equipment known as fermenters or bioreactors, which are designed to maintain an oxygen-free environment, suitable for the growth of anaerobic microorganisms. Here's an overview of the fermenter and its essential accessories used in anaerobic fermentation:

 

1. Fermenter (Anaerobic Bioreactor)

The fermenter is the core vessel where the fermentation process takes place. For anaerobic fermentation, certain features are essential to maintain the correct conditions:

• Airtight Design: The fermenter must be airtight to ensure no oxygen enters the system, maintaining the anaerobic conditions necessary for the growth of anaerobic microorganisms.
• Material: Typically made from stainless steel, glass, or special polymers that are resistant to corrosion, and allow easy cleaning and sterilization.
• Temperature Control: The fermenter is equipped with a jacket or internal heat exchangers to control the temperature, as many fermentation processes are sensitive to temperature variations.
• Agitator/Stirrer: In some cases, a gentle stirrer is used to keep the fermentation medium homogenous and to help distribute nutrients, though it should not introduce oxygen into the system.

2. Accessories Used in Anaerobic Fermentation

To maintain optimal conditions inside the fermenter, several accessories are essential:

1. Gas Inlet/Outlet System:

• Inert Gas Supply (Nitrogen, CO₂): To create and maintain anaerobic conditions, the fermenter is purged with an inert gas like nitrogen or carbon dioxide. This ensures that all oxygen is expelled from the vessel before the fermentation begins.
• Gas Collection System: The gases produced during fermentation, such as CO₂ or methane (in the case of methanogenic bacteria), are collected and vented or further processed.

2. pH Control System:

• pH Probes: Continuously monitor the acidity or alkalinity of the fermentation medium.
• Acid/Base Dosing System: Based on the pH probe readings, the system can automatically add acid or base to maintain the desired pH levels, as microorganisms often require a specific pH for optimal growth and metabolism.

3. Sampling Port:

• Provides a way to take samples of the fermentation broth without introducing oxygen into the system. It is often equipped with valves to prevent contamination.

4. Nutrient Feed System:

• In some fermentation processes, a continuous or semi-continuous supply of nutrients is necessary. A feed pump or peristaltic pump is used to introduce nutrients like sugars, nitrogen sources, or other essential compounds without exposing the fermenter to air.

5. Temperature Control System:

• Thermocouples/Temperature Probes: Measure the temperature inside the fermenter.
• Heating/Cooling Jacket: A jacket or coil surrounding the fermenter allows for precise heating or cooling. This can be connected to a water bath or a heating/cooling system to regulate the temperature.

6. Anti-Foam System:

• Fermentation processes can produce foam due to the metabolic activity of microorganisms. To control this, foam sensors are used to detect foam levels, and an anti-foam agent can be automatically added via a pump.

7. Pressure Control System:

• For anaerobic fermentations that produce gases (e.g., biogas fermentation), pressure buildup can occur inside the fermenter. A pressure release valve is used to control the internal pressure and prevent damage to the fermenter.

8. Agitation System:

• In anaerobic fermentation, oxygen must be excluded, so the agitator is often designed to prevent the introduction of air. The impellers used in anaerobic systems are often specialized to ensure proper mixing of the broth without introducing oxygen. In some cases, a mechanical or magnetic stirrer is used.

9. Sterilization Ports/Systems:

• Sterile filters are placed on the gas inlet/outlet to prevent contamination. The entire system can also be sterilized using steam or chemical agents before the fermentation starts to ensure a sterile environment.

3. Control System

Anaerobic fermenters are often equipped with advanced control systems that monitor and adjust various parameters such as temperature, pH, gas composition, and pressure, ensuring optimal fermentation conditions are maintained.

Common Uses of Anaerobic Fermentation:

• Biogas Production: Anaerobic digestion of organic material to produce methane.
• Ethanol Production: From the fermentation of sugars by yeast.
• Lactic Acid Production: Through fermentation by lactic acid bacteria.
• Pharmaceuticals/Biochemicals: Some pharmaceutical and biochemical compounds are produced by anaerobic microbes.

In summary, anaerobic fermenters are highly specialized vessels with a range of accessories designed to maintain strict anaerobic conditions and optimize microbial growth and product formation.