Microbial corrosion, also known as microbiologically influenced corrosion (MIC), is a type of corrosion that occurs as a result of the activity of microorganisms such as bacteria, archaea, and fungi. These microorganisms can attach themselves to metal surfaces and create an environment that is conducive to corrosion.

What causes microbial corrosion?

Microbiologically influenced corrosion (MIC), can be caused by a number of factors;

1. Biofilm formation: Microorganisms can attach themselves to metal surfaces and create a biofilm, which can trap water and nutrients, and create an environment that is conducive to corrosion.
2. Changes in pH: Changes in pH can alter the electrochemical properties of metal surfaces, which can make them more susceptible to corrosion.
3. Oxygen depletion: Microorganisms can consume oxygen and create an anaerobic environment, which can promote corrosion.
4. Organic and inorganic compounds: Microorganisms can produce organic and inorganic compounds that can act as electron donors or acceptors and accelerate the corrosion process.
5. Temperature: Changes in temperature can alter the rate of microbial activity and therefore affect the rate of corrosion.
6. Water chemistry: The chemical composition of the water can affect the rate of corrosion, as certain ions can react with the metal surface and accelerate the corrosion process.
7. Type of microorganisms: Different types of microorganisms can produce different chemicals and enzymes that can affect the rate of corrosion.
8. Nutrient availability: The availability of nutrients such as carbon, nitrogen, and phosphorus can affect the rate of microbial activity and therefore affect the rate of corrosion.
9. Presence of inhibitors: Some microorganisms can produce inhibitors that can reduce the rate of corrosion, while others can produce enzymes that can break down inhibitors and increase the rate of corrosion.

How to recognize microbial corrosion?

Microbial corrosion, also known as microbiologically influenced corrosion (MIC), can be difficult to recognize because it often occurs beneath the surface of the metal and is not visible to the naked eye. However, there are some signs that may indicate the presence of MIC. These include:

1. Pitting or localized corrosion: MIC can cause pitting or localized corrosion on the metal surface. The corrosion may be irregular in shape and can occur in clusters.
2. Discoloration: The metal surface may become discolored or stained due to the formation of corrosion products.
3. Changes in surface texture: The surface texture of the metal may change due to the formation of a biofilm or the accumulation of corrosion products.
4. Reduced thickness: MIC can cause a reduction in the thickness of the metal, which can weaken the structure and potentially cause it to fail.
5. Increased roughness: The surface of the metal may become rough or uneven due to the formation of corrosion products or the activity of microorganisms.
6. Presence of biofilms: The presence of biofilms on the metal surface can indicate the presence of microorganisms that may be causing corrosion.

If you suspect that microbial corrosion may be occurring, it is important to conduct a thorough inspection of the metal surface and surrounding environment. This may include sampling and analysis of the water or soil to determine the presence of microorganisms and other factors that may be contributing to corrosion. Early detection of microbial corrosion is important to prevent further damage and potential failure of the metal structure.

Microbial corrosion in our daily life

Microbial corrosion, also known as microbiologically influenced corrosion (MIC), can occur in a variety of environments, including daily life. Here are some examples of MIC in daily life:

1. Plumbing systems: MIC can occur in plumbing systems due to the presence of microorganisms in the water. The corrosion can cause leaks and damage to pipes and fixtures.
2. Boat hulls: Boat hulls are often exposed to water, which can provide an environment for the growth of microorganisms. MIC can cause corrosion on the hull, which can weaken the structure and potentially lead to failure.
3. Oil and gas pipelines: MIC can occur in oil and gas pipelines due to the presence of microorganisms in the fluid. The corrosion can cause leaks and damage to the pipeline, which can be expensive to repair.
4. Cooling systems: MIC can occur in cooling systems, such as air conditioning units and refrigerators, due to the presence of water and nutrients. The corrosion can cause damage to the system and potentially lead to failure.
5. Dental implants: MIC can occur in dental implants due to the presence of microorganisms in the mouth. The corrosion can cause damage to the implant and potentially lead to failure.
6. Food processing equipment: MIC can occur in food processing equipment due to the presence of microorganisms in the food or water. The corrosion can cause damage to the equipment and potentially contaminate the food.
7. Automobiles: MIC can occur in automobiles due to the presence of moisture and microorganisms in the fuel tanks and cooling systems. The corrosion can cause damage to the metal parts of the engine and potentially lead to failure.
8. Swimming pools: MIC can occur in swimming pools due to the presence of microorganisms in the water. The corrosion can cause damage to the metal parts of the pool, such as the ladder, and potentially lead to failure.
9. Metal sculptures: MIC can occur in metal sculptures that are exposed to outdoor environments, such as parks and gardens. The corrosion can cause damage to the sculpture and potentially lead to failure.
10. Industrial equipment: MIC can occur in industrial equipment that is exposed to water or other fluids. The corrosion can cause damage to the equipment and potentially lead to failure, which can be costly in terms of repairs and downtime.
11. Household appliances: MIC can occur in household appliances, such as washing machines and dishwashers, due to the presence of water and microorganisms. The corrosion can cause damage to the appliance and potentially lead to failure.

How to prevent microbial corrosion?

Preventing microbial corrosion involves taking measures to reduce or eliminate the growth and activity of microorganisms that contribute to corrosion. Here are some ways to prevent microbial corrosion:

1. Maintain good sanitation: Regular cleaning and sanitation of surfaces and equipment can help to reduce the growth of microorganisms and prevent corrosion.
2. Use biocides: Biocides are chemicals that can be used to kill microorganisms. They can be used in water systems, such as cooling towers and pipelines, to control the growth of microorganisms that contribute to corrosion.
3. Use corrosion inhibitors: Corrosion inhibitors are chemicals that can be added to water or other fluids to reduce the corrosion of metal surfaces. Some corrosion inhibitors can also have a biocidal effect, which can help to control the growth of microorganisms.
4. Control environmental factors: Environmental factors such as temperature, pH, and oxygen levels can affect the growth and activity of microorganisms. Controlling these factors can help to prevent microbial corrosion.
5. Use appropriate materials: Using materials that are resistant to corrosion can help to prevent microbial corrosion. For example, using stainless steel instead of carbon steel in a water system can reduce the growth of microorganisms and prevent corrosion.
6. Monitor and test regularly: Regular monitoring and testing of water and other fluids can help to identify the presence of microorganisms and corrosion. This can help to detect problems early and take corrective action before significant damage occurs.

By implementing these measures, it is possible to prevent microbial corrosion and protect metal surfaces from damage and failure. It is important to understand the specific conditions and factors that contribute to microbial corrosion in each environment, in order to develop an effective prevention strategy.