MDE Unit 10 Q7

Microbial degradation is the process by which microorganisms (bacteria and fungi) break down lubricating oil into simpler compounds. This occurs when specific conditions are met, primarily the presence of water and suitable temperatures.  

1. Biodegradation: Involved Microorganisms and Genetically Engineered Microorganisms | IntechOpen

2. Microbial Degradation Marine Lubricating Oils

How it Happens

• Water ingress: Water is essential for microbial growth. It can enter the oil system through various means, such as leaks, condensation, or improper storage.   1. Microorganisms populating the water-related indoor biome | Applied Microbiology and Biotechnology – SpringerLink link.springer.com2. The consequences of water contamination in lubricating oil – Poc Filtros www.pocfiltros.com.br
• Nutrient availability: The oil itself provides nutrients for microorganisms, particularly the additives and base oil components.
• Temperature: Moderate temperatures, often found in engine sumps or storage tanks, are ideal for microbial growth.

Consequences of Microbial Degradation

• Oil thickening: Microorganisms produce substances that can thicken the oil, leading to increased friction and reduced engine performance.
• Acid formation: The metabolic processes of microorganisms can create acidic compounds that corrode engine components.   1. Microbial Degradation of lubricating oils onboard – DieselShip dieselship.com
• Sludge formation: Microbial growth can result in the formation of sludge, which can clog oil filters and passages.
• Emulsion formation: Microbes can contribute to the formation of stable water-in-oil emulsions, further degrading the oil’s properties.

Prevention

To prevent microbial degradation, it’s crucial to:

• Minimize water ingress: Implement proper sealing and drainage systems.
• Maintain oil cleanliness: Regular oil changes and filter replacements are essential.
• Control temperature: Ensure proper engine operating temperatures and storage conditions.
• Use biocides: In some cases, biocide additives can be used to inhibit microbial growth.   1. Microbial Contamination in Lubricants: How to Detect and Treat Them? – Redlist www.getredlist.com

By understanding the factors contributing to microbial degradation and taking preventive measures, you can significantly extend the life of your lubricating oil and protect your engine.

Microbial degradation can lead to several observable changes in the lubricating oil and engine performance. Here are some key indicators:  

1. Microbial Degradation of lubricating oils onboard – DieselShip

Oil Appearance and Consistency Changes

• Thickening: The oil may become thicker or more viscous than normal.
• Sludge formation: Dark, sticky deposits can form, leading to clogged filters and oil passages.
• Emulsions: Water-in-oil emulsions can create a milky or cloudy appearance.
• Unusual odors: A foul, rotten egg smell can be indicative of microbial activity.   1. Microbial Degradation of lubricating oils onboard – DieselShip dieselship.com

Engine Performance Issues

• Increased wear: Thickened oil and acidic conditions can accelerate engine wear.
• Reduced engine performance: Increased friction due to thickened oil can lead to power loss.
• Overheating: Reduced oil flow due to sludge can cause engine overheating.   1. What Is Oil Sludge and How Does It Hurt My Car? – Lex Brodie’s www.lexbrodies.com
• Increased fuel consumption: Increased engine friction can lead to higher fuel consumption.

Other Signs

• Corrosion: Acidic conditions can cause corrosion of engine components.
• Filter plugging: Frequent filter clogging can be a symptom of microbial contamination.   1. Microbial Degradation of lubricating oils onboard – DieselShip dieselship.com
• Bearing failures: Increased wear and reduced lubrication can lead to bearing failures.

Note: These are general indicators, and confirming microbial contamination often requires laboratory analysis.

Early detection of microbial degradation in main engine lubricating oil is crucial to prevent severe engine damage. Here are the actions to be taken:

Immediate Actions:

1. Oil Sampling: Collect oil samples from various points in the system (sump, filter, etc.) for laboratory analysis to confirm microbial contamination.
2. Visual Inspection: Check for any signs of sludge, emulsion, or discoloration in the oil.
3. Filter Inspection: Examine the oil filter for unusual deposits or blockages.
4. Water Removal: If water is present, take steps to remove it through purification or draining.   1. Microbial Degradation of lubricating oils onboard – DieselShip dieselship.com
5. Increase Oil Purification: Intensify the operation of the oil purifier to remove contaminants.
6. Monitor Engine Performance: Closely monitor engine parameters like temperature, pressure, and vibration for any anomalies.

Preventive Measures:

1. Regular Oil Analysis: Implement a regular oil analysis program to detect early signs of degradation.
2. Biocide Treatment: Consider using a biocide additive, but only after consulting with the oil manufacturer.
3. Improved Filtration: Upgrade to higher efficiency filters to remove contaminants more effectively.
4. Water Control: Prevent water ingress into the system through proper sealing and maintenance.
5. Oil Storage: Ensure proper storage conditions for new oil to prevent contamination.
6. Cleaning: Thoroughly clean oil tanks and lines to remove any microbial deposits.

Long-Term Measures:

1. Root Cause Analysis: Investigate the source of the contamination to prevent recurrence.
2. Maintenance Schedule Review: Adjust maintenance intervals based on the findings of the oil analysis.
3. Crew Training: Provide training to the crew on early signs of microbial contamination and corrective actions.

Remember: Early detection and prompt action are key to preventing severe engine damage caused by microbial degradation. Consulting with lubricant experts and following manufacturer guidelines is essential for effective management.