In fields such as biopharmaceuticals, food brewing, and fermentation engineering, the Fermentation Tank is one of the most critical pieces of equipment. Whether used for beer brewing, probiotic production, or biopharmaceutical fermentation, the performance and lifespan of the fermentační nádrž directly impact product yield and quality. However, even high-end fermentation tanks made of stainless steel can experience corrosion, contamination, leakage, or performance degradation if not properly maintained and operated.
This article will systematically explain how to extend the lifespan of fermentation tanks through scientific care and maintenance, reduce equipment failure rates, and help enterprises improve production efficiency and return on investment.
Why Should We Pay Attention to Daily Maintenance of Fermentation Tanks?
Fermentation tanks operate in high-temperature, high-humidity environments rich in nutrients, conditions that promote microbial growth but also lead to issues like biological film deposition, metal corrosion, and microbial contamination.
If daily maintenance is neglected, common problems include:
- Corrosion and rusting of the tank, affecting structural strength
- Sensor and valve malfunctions, leading to control failures
- Contaminated batches being discarded, resulting in economic losses
- Decreased yields or unstable fermentation, impacting product quality
Therefore, proper fermentation tank maintenance and cleaning is not only key to extending equipment life but also an essential factor in ensuring production safety and product quality.
Choosing the Right Material: The First Step to Extending the Lifespan
A high-quality fermentation tank starts with the selection of appropriate materials. Different materials exhibit significant differences in corrosion resistance and cleaning difficulty.
Comparison of Common Fermentation Tank Materials:
Materiál | Funkce | Applicable Fields |
SUS304 Stainless Steel | Low cost, good corrosion resistance | General food, beverage fermentation |
SUS316L Stainless Steel | Contains molybdenum, stronger resistance to acids and alkalis | Biopharmaceuticals, high-salt fermentation |
Glass-lined Tank | Resistant to strong acids and alkalis, less prone to contamination | Chemical industry, biochemical labs |
Enamel Fermentation Tank | Strong chemical corrosion resistance | Special biochemical reactions |
Recommendations:
- For overseas clients or the biopharmaceutical industry, SUS316L stainless steel fermentation tanks are recommended.
- The surface roughness should be controlled at Ra ≤ 4 μm to reduce microbial attachment.
- Welding seams should undergo automatic welding and polishing treatments to prevent residual contamination sources.
Cleaning and Sterilization of Fermentation Tanks: Core Maintenance Steps
In the daily maintenance of fermentační zařízení, cleaning and sterilization of the fermentation tank is the most critical and key process. Since the fermentation tank directly contacts culture media, microorganisms, and metabolic products during production, inadequate cleaning or insufficient sterilization can lead to microbial cross-contamination, fermentation failure, or even equipment corrosion. Therefore, maintaining a clean and sterile interior of the fermentation tank is essential to ensure product quality and extend equipment lifespan.
Using CIP/SIP Systems for Efficient Cleaning
Modern fermentation production typically uses a combination of CIP (Clean-in-Place) and SIP (Sterilize-in-Place) systems for automatic cleaning and sterilization of fermentation tanks and pipes. These systems do not require manual disassembly, and can perform closed-loop cleaning, effectively preventing secondary contamination, improving cleaning efficiency, and ensuring traceability.
A standard CIP cleaning process generally includes five stages:
- Pre-rinse with warm water (40–50°C): Removes residual culture media and impurities from the tank.
- Alkaline solution circulation (0.5%–2% NaOH): Removes proteins and organic dirt.
- Acid cleaning (0.5%–1% HNO₃ or H₃PO₄): Dissolves scale and removes deposits.
- Rinsing with pure water: Ensures no chemical residue.
- Steam or chemical sterilization: Maintains a high temperature of 121°C or uses peracetic acid sterilization to ensure a sterile environment.
Through automated CIP/SIP systems, not only can human error be minimized, but cleaning parameters are also automatically recorded, meeting GMP and international sanitation standards.
Proper Cleaning Frequency and Safe Chemical Use
The frequency of cleaning and sterilization should be determined based on the type of fermentation and production batch. For continuous fermentation, cleaning and sterilization should be performed immediately after each fermentation cycle. For intermittent or long-term idle fermentation tanks, cleaning and drying should be carried out before downtime to prevent bacterial growth or tank corrosion.
At the same time, it is crucial to avoid using chlorine-based cleaning agents, as they can damage the stainless steel’s passivation layer. It is recommended to use food-grade alkaline solutions, acid solutions, and chlorine-free disinfectants. Regular stainless steel passivation (Passivation) treatment can further enhance the fermentation tank’s corrosion resistance and surface smoothness.
Maintain Cleanliness to Extend Lifespan
A scientific cleaning and sterilization process for fermentation tanks not only ensures the stability of each fermentation batch but also significantly reduces equipment wear and maintenance costs. For overseas clients or large factories, establishing a comprehensive CIP/SIP system and Standard Operating Procedures (SOPs), along with regular testing and training, can ensure that fermentation tanks remain in optimal working condition. This helps businesses maintain a competitive edge in the global market.
Daily Inspection and Maintenance of Mechanical Components
Seals and Gaskets
- Regularly inspect O-rings, sealing gaskets, and mechanical seals.
- Replace immediately if signs of aging, deformation, or cracks are found.
- Use food-grade silicone or EPDM seals that are resistant to high temperature and acid/alkali environments.
Valves and Connections
- Regularly open sampling valves and drain valves to check for blockages.
- Ensure valves operate smoothly to prevent leakage.
- Lubricate mechanical connections to maintain sealing reliability.
Agitation System
- Check whether the agitator shaft is centered and if the impellers are worn.
- Regularly lubricate bearings.
- Monitor the motor current to prevent overload during operation.
Key Parameters to Monitor During Fermentation Tank Operation
- During fermentation tank operation, real-time monitoring of key parameters is essential to ensure stable fermentation and extend the lifespan of the equipment. The main parameters to monitor include temperature, pressure, pH, dissolved oxygen (DO), agitator speed, and foam levels.
- Temperature and pressure directly affect both the safety of the tank and microbial activity. Excessive temperature can kill microorganisms or cause thermal stress damage to the tank, while abnormal pressure may lead to leaks or valve failure. These parameters should be maintained stable using an automatic control system.
- pH and dissolved oxygen (DO) are critical indicators of fermentation status. Large fluctuations in pH or consistently low DO often indicate sensor contamination or insufficient agitation/aeration. Sensors should be cleaned and calibrated regularly to ensure accurate monitoring.
- Agitation and foam control also require attention. Excessive stirring can lead to mechanical wear, while insufficient agitation causes uneven mixing. Excessive foam can create contamination risks and should be managed with foam detection and automatic antifoaming devices.
- By implementing a comprehensive parameter monitoring and alarm system, operators can quickly detect abnormalities, prevent overload or damage to the fermentation tank, and ensure stable operation while extending equipment lifespan.
Tips to Prevent Corrosion and Surface Damage
- Avoid chlorine-based cleaning agents: Chloride ions can damage the passivation layer on stainless steel fermentation tanks, leaving the metal exposed to air and moisture, which can cause pitting corrosion. It is recommended to use food-grade alkaline and acid solutions for CIP cleaning, such as sodium hydroxide, nitric acid, or phosphoric acid, and to rinse thoroughly to avoid chemical residues.
- Perform regular passivation: The passivation layer on stainless steel protects against corrosion. It is recommended to carry out acid passivation treatment every 6–12 months to restore the dense oxide layer on the metal surface, enhancing corrosion resistance and maintaining a smooth, clean tank interior.
- Keep dry to prevent electrochemical corrosion: After cleaning, drain residual water and use sterile air to dry the tank. This prevents residual liquid from causing electrochemical reactions in welds or low points. Also, keep the exterior of the tank dry and avoid long-term exposure to humid environments.
- Prevent mechanical scratches and impacts: During installation or maintenance, avoid contact with hard objects that could scratch or dent the tank interior. Small damages can become hidden spots for microbial growth, affecting cleaning efficiency and sanitary performance.
- Enhance storage and protection: For temporarily unused tanks or tanks in transit for export, ensure ventilated and dry storage, and install dust covers or filters on interfaces and valves to prevent dust and moisture ingress. For long-term storage, applying a protective coating inside the tank can further enhance rust resistance.
Precautions for Fermentation Tank Shutdown and Storage
If a fermentation tank will be out of service for an extended period, proper protective measures should be taken:
- Drain and thoroughly rinse any remaining liquid inside the tank.
- Dry the interior using sterile air.
- Open the manhole and valves to maintain ventilation.
- Install filters on sealed connections to prevent dust from entering.
- Store the tank in a dry, cool, and well-ventilated environment.
When to Consider Component Replacement or Equipment Upgrades
Tank Corrosion or Structural Damage
If the inner wall of a fermentation tank shows obvious corrosion, pitting, or weld cracks, an immediate inspection and evaluation are necessary. Minor corrosion can be restored through polishing and passivation, but if the tank’s structure is compromised or sealing is affected, timely replacement is required to prevent contamination risks or safety hazards.
Aging Seals and Frequent Leaks
During long-term operation, O-rings, gaskets, and valves can deteriorate due to high temperature, high pressure, or chemical cleaning. If leaks or poor sealing occur, the affected components should be replaced immediately. It is recommended to use food-grade EPDM or PTFE seals to enhance corrosion resistance and service life.
Outdated Control Systems
Traditional fermentation tanks often rely on manual or semi-automatic controls. Modern fermentation processes demand precise regulation of temperature, pH, dissolved oxygen (DO), and pressure. If existing control systems cannot meet process requirements or lack data recording and alarm functions, consider upgrading to a PLC or intelligent control system for automated monitoring and remote management.
Declining Cleaning and Sterilization Efficiency
If CIP or SIP systems take longer to clean, fail to sterilize thoroughly, or consume more energy, spray heads, pipelines, or heating elements may be worn or clogged. At this stage, the cleaning system should be repaired or replaced, and in some cases, upgraded to a high-efficiency, energy-saving automated CIP system to improve cleaning effectiveness and reduce energy consumption.
High Energy Consumption and Increased Maintenance Costs
When energy usage rises significantly, maintenance frequency increases, or replacement costs approach the price of new equipment, it is time to consider a full equipment upgrade. Modern fermentation tanks often feature energy-efficient agitators, optimized tank design, and intelligent monitoring modules, reducing operating costs while improving productivity and safety.
Process Expansion or New Product Lines
As production capacity expands or product lines increase, existing fermentation tanks may no longer meet the new scale requirements. Consider increasing tank capacity, adding parallel systems, or adopting higher-automation equipment to match new fermentation processes and market demands.
Závěr
Through scientific maintenance and care, fermentační nádrže can operate efficiently and stably over the long term. From cleaning and sterilization to real-time monitoring of key parameters like temperature and pressure, proper maintenance is essential for product quality and equipment longevity.Regularly inspecting mechanical components for wear and aging, and performing timely component replacement or equipment upgrades, can reduce failure rates, increase production efficiency, and lower maintenance costs.
Additionally, preventing corrosion and surface damage, and ensuring sealing integrity and structural soundness, are crucial for extending the tank’s service life. With regular passivation and meticulous care, corrosion and contamination can be effectively prevented, ensuring a sterile and stable fermentation process.
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