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 is a complex process that is influenced by several factors. Understanding these factors can help prevent and detect microbial corrosion. Here are some of the main factors that impact the process:

1. Presence of microorganisms: Microbial corrosion cannot occur without the presence of microorganisms. Bacteria, fungi, and other microorganisms can colonize metal surfaces and create biofilms, which provide a protective environment for the microorganisms and promote corrosion.
2. Nutrient availability: Microorganisms require nutrients to grow and survive, and the availability of nutrients can affect the rate and severity of microbial corrosion. For example, the presence of organic matter or sulfates in the environment can provide a food source for sulfate-reducing bacteria, which are known to cause corrosion.
3. pH: The pH of the environment can also affect the growth and activity of microorganisms, and therefore the rate of microbial corrosion. Some microorganisms are more active at acidic or alkaline pH levels, while others thrive in more neutral environments.
4. Temperature: Temperature can also play a role in promoting microbial corrosion. Some microorganisms are more active at higher temperatures, while others are more active at lower temperatures.
5. Oxygen availability: The presence or absence of oxygen can also affect the growth and activity of microorganisms and the rate of microbial corrosion. Some microorganisms require oxygen to survive and can cause corrosion in areas with high oxygen concentrations, while others thrive in low-oxygen environments.

How to recognize microbial corrosion?

Microbial corrosion, 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 microbial corrosion.

1. When trying to identify microbial corrosion, it’s important to look for certain signs. Biofilms, which are colonies of microorganisms that adhere to the metal surface and create a protective environment, are a strong indicator of potential microbial corrosion.
2. Pitting, localized corrosion, and uneven surface roughness are also common signs of microbial corrosion. The corrosion damage may be irregular in shape and can occur in clusters, which can differentiate it from other forms of corrosion.
3. Another sign of microbial corrosion is the change in the appearance of the metal surface. The formation of corrosion products can cause discoloration or staining, which may be visible to the naked eye. However, it’s important to note that microbial corrosion often occurs beneath the surface of the metal and may not be visible until significant damage has occurred.
4. Microbial corrosion can also cause a reduction in the thickness of the metal, which can weaken the structure and potentially cause it to fail. This can be especially dangerous in critical applications such as pipelines, where a failure can result in significant environmental or safety hazards.

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 can occur in various settings, from industrial equipment to household items. Here are some examples of microbial corrosion in daily life:

1. Microbial corrosion can occur in plumbing systems due to the presence of microorganisms in the water. These microorganisms can form colonies on the inner surfaces of pipes and fixtures, where they produce acidic substances that can slowly eat away at the metal. Over time, this can lead to leaks and damage to the plumbing system.
2. Boat hulls are particularly susceptible to microbial corrosion, as they are constantly exposed to water, which provides an ideal environment for the growth of microorganisms. Microbial corrosion on boat hulls, also known as biofouling, can weaken the structure of the hull and potentially lead to catastrophic failure if not addressed.
3. Microbial corrosion can also be a significant problem in oil and gas pipelines, where the presence of microorganisms in the fluid can cause corrosion on the inner surfaces of the pipes. This corrosion can weaken the pipeline and potentially lead to leaks, which can pose environmental hazards.
4. Cooling systems, such as air conditioning units and refrigerators, can also be susceptible to microbial corrosion due to the presence of water and nutrients that can support the growth of microorganisms. The resulting corrosion can cause damage to the system, reduce its efficiency, and potentially lead to system failure.
5. Dental implants can be susceptible to microbial corrosion due to the presence of microorganisms in the mouth. The resulting corrosion can cause damage to the implant and potentially lead to implant failure, which can be painful and require replacement.
6. Food processing equipment is also vulnerable to microbial corrosion due to the presence of microorganisms in the food or water used in the equipment. The corrosion can cause damage to the equipment and potentially contaminate the food, leading to food safety concerns and costly recalls.
7. Automobiles can be susceptible to microbial corrosion 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, potentially leading to engine failure and expensive repairs.
8. Swimming pools can be prone to microbial corrosion 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 pool failure, which can be dangerous and costly to repair.
9. Outdoor metal sculptures, such as those found in parks and gardens, are also vulnerable to microbial corrosion. Exposure to the elements can provide an ideal environment for the growth of microorganisms, which can cause damage to the sculpture and potentially lead to its failure.
10. Industrial equipment that is exposed to water or other fluids can also be vulnerable to microbial corrosion. The resulting corrosion can cause damage to the equipment and potentially lead to system failure, resulting in costly repairs and downtime.
11. Household appliances, such as washing machines and dishwashers, can be susceptible to microbial corrosion due to the presence of water and microorganisms. The resulting corrosion can cause damage to the appliance and potentially lead to failure, requiring repairs or replacement.

How to prevent microbial corrosion?

Preventing microbial corrosion is essential to ensure the longevity and safety of metal structures and equipment. Here are some ways to prevent microbial corrosion in more detail:

1. Maintain good sanitation: Regular cleaning and sanitizing of surfaces and equipment can prevent the build-up of biofilms and reduce the growth of microorganisms. This can be achieved through various methods, such as cleaning with detergents and hot water or using high-pressure cleaning techniques.
2. Use biocides: Biocides are chemicals that can be used to kill microorganisms. They are commonly used in water systems, such as cooling towers and pipelines, to control the growth of microorganisms that contribute to corrosion. Biocides should be chosen carefully and used in accordance with manufacturer instructions and regulatory requirements.
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 also have a biocidal effect, which can help to control the growth of microorganisms. Corrosion inhibitors should be selected based on the type of metal and the environmental conditions.
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. For example, reducing the temperature of a water system can slow down the growth of microorganisms.
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. Using appropriate coatings can also help to protect metal surfaces from microbial 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. Monitoring should include regular microbiological testing, as well as physical and chemical testing to assess corrosion and other factors that can contribute to metal degradation.

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.