Steps and precautions for using stainless steel fermentation tanks

‌Stainless Steel Fermentation Tank: Operating Procedures and Precautions‌

Below are the ‌operating steps and precautions for stainless steel fermentation tanks‌, covering procedures, safety protocols, and maintenance guidelines. Applicable to industries such as food, pharmaceuticals, and bioengineering:

‌I. Operating Procedures‌

‌1. Preparation‌

• ‌Cleaning and Sterilization‌:
  • Thoroughly clean the tank body, agitator, pipelines, and other components before use to remove residues.
  • Sterilize using high-temperature steam (121°C for 30 minutes) or chemical disinfectants (e.g., 75% ethanol, peracetic acid) to ensure an aseptic environment.
• ‌Equipment Inspection‌:
  • Verify the integrity of seals, valves, pressure gauges, temperature sensors, and other accessories.
  • Test the functionality of the agitator motor, temperature control system, and pH/DO probes.
• ‌Material Preparation‌:
  • Prepare culture media or fermentation substrates according to process requirements, sterilized via filtration (e.g., 0.22μm membrane).
  • Adjust initial parameters (temperature, pH, dissolved oxygen).

‌2. Loading and Startup‌

• ‌Loading‌:
  • Introduce sterilized media or substrates through the feed port, ensuring the filling volume does not exceed 70% of the tank capacity (to prevent foam overflow).
  • Seal the tank and check flange clamps for tightness to avoid leaks.
• ‌Parameter Setup‌:
  • Set fermentation temperature (e.g., 30–37°C), agitation speed (adjust based on microbial requirements), and sterile airflow rate (filtered through sterile air filters).
  • Connect pH/DO probes and configure automated feeding or pH adjustment systems (e.g., glucose supplementation, ammonia addition).

‌3. Fermentation Process Control‌

• ‌Real-Time Monitoring‌:
  • Record temperature, pressure, agitation speed, pH, and dissolved oxygen. Monitor foam levels (add antifoam agents if necessary).
  • Periodically sample to assess cell density, product concentration, and contamination (e.g., foreign microbes, phages).
• ‌Dynamic Adjustments‌:
  • Modify airflow rate based on metabolic phases (e.g., high oxygen in early stages, low oxygen later) or feeding rates.
  • Optimize agitation intensity to balance dissolved oxygen and shear stress (avoid cell damage).

‌4. Termination and Unloading‌

• ‌Termination Criteria‌:
  • Stop fermentation when target product concentration, stationary growth phase, or preset duration is reached.
  • Disable heating, agitation, and aeration systems, then slowly release internal pressure.
• ‌Unloading and Cleaning‌:
  • Collect fermentation broth via the bottom discharge port to prevent contamination.
  • Rinse the tank immediately with water to remove residues. Perform deep cleaning with alkaline (NaOH) or acidic (HNO₃) solutions if required.

‌II. Precautions‌

‌1. Safety Protocols‌

• ‌Pressure and Explosion Prevention‌:
  • Never exceed the maximum operating pressure (typically ≤0.3 MPa). Regularly calibrate safety valves and pressure gauges.
  • Ensure vent valves are open during sterilization or cleaning to prevent tank deformation from residual steam or liquids.
• ‌Electrical and Mechanical Safety‌:
  • Inspect motor and cable insulation to prevent electrical leakage.
  • Never open the tank lid or touch rotating parts during operation.

‌2. Hygiene and Contamination Control‌

• ‌Aseptic Practices‌:
  • Sterilize all pipelines, interfaces, and tools. Operators must wear sterile suits and gloves.
  • Replace or sterilize air filters (e.g., PTFE membranes) regularly to prevent microbial contamination.
• ‌Cross-Contamination Prevention‌:
  • Clean the tank thoroughly between batches or different microbial strains to avoid residue interference.

‌3. Equipment Maintenance‌

• ‌Routine Care‌:
  • Inspect seal elasticity after each use and replace worn or damaged parts promptly.
  • Lubricate agitator shafts and bearings to prevent friction-induced overheating or jamming.
• ‌Long-Term Storage‌:
  • Drain all liquids, keep the tank dry, and ensure ventilation to avoid moisture buildup.
  • Protect sensors and gauges from dust and corrosion.

‌4. Special Material Handling‌

• ‌Corrosive Substances‌:
  • For media containing strong acids, bases, or salts, use 316L stainless steel or corrosion-resistant linings.
  • Avoid chloride ion (Cl⁻) residues during cleaning (risk of stainless steel pitting).
• ‌High-Viscosity Materials‌:
  • Use anchor or helical agitators to prevent material sedimentation.

‌III. Common Issues and Troubleshooting‌

• ‌Contamination‌: Terminate fermentation immediately, sterilize the tank, and trace contamination sources (e.g., air filters, incomplete material sterilization).
• ‌Foam Overflow‌: Reduce agitation speed, add antifoam agents, or manually remove foam.
• ‌Temperature Fluctuations‌: Check temperature control circuits or cooling water flow. Activate manual cooling in emergencies.

‌IV. Summary‌

Efficient use of stainless steel fermentation tanks relies on standardized operations and diligent maintenance:

1. ‌Strict sterilization and aseptic practices‌ are critical for successful fermentation.
2. ‌Real-time monitoring and adjustments‌ ensure process stability.
3. ‌Regular maintenance‌ extends equipment lifespan and reduces downtime.
4. ‌Safety measures‌ prevent personnel injury and material loss.

Tailor procedures to specific process requirements and equipment manuals. Professional training is recommended for operators.