In industrial water systems, corrosion is more than just a nuisance—it’s a costly and potentially dangerous problem that can impact system performance, safety, and longevity. While many people associate corrosion with purely chemical or electrochemical reactions, biological contamination plays a surprisingly significant role in accelerating and complicating corrosion processes.
At Fact Water Co., we specialize in understanding and controlling the many variables that lead to corrosion in water systems. One of the most complex and often overlooked contributors is Microbiologically Influenced Corrosion (MIC)—corrosion caused or exacerbated by microbial activity
What Is Microbiologically Influenced Corrosion (MIC)?
MIC occurs when microorganisms, especially bacteria, colonize metal surfaces within a water system and either directly or indirectly accelerate corrosion. These microbes form biofilms, which are slimy layers of bacteria and organic material that adhere to surfaces like pipes, tanks, and heat exchangers.
While biofilms might seem harmless, they create microenvironments that can drastically alter the local chemistry, making it more corrosive. For example, certain bacteria produce acidic by-products, trap oxygen, or generate corrosive gases like hydrogen sulfide, all of which can deteriorate metal surfaces. Corrosion may otherwise occur on its own, but the influence of bacteria speeds that process up considerably, causing bigger problems much more quickly.
Key Microorganisms Involved in MIC
Several types of bacteria are known to contribute to MIC, including:
- Sulfate-reducing bacteria (SRB): These anaerobic microbes produce hydrogen sulfide (H₂S), a corrosive gas that can cause pitting and localized metal failure.
- Iron-oxidizing bacteria (IOB): These bacteria oxidize ferrous ions to form rust-like deposits, which can clog systems and promote under-deposit corrosion.
- Slime-forming bacteria: These contribute to thick biofilms that create differential oxygen concentrations—leading to oxygen concentration cells and localized corrosion.
How MIC Affects Industrial Water Systems
Biological contamination doesn’t just affect metal integrity—it disrupts the entire water treatment process. Here are some ways MIC can damage or hamper industrial water system operations:
- Localized Corrosion (Pitting): MIC often leads to highly localized attacks, forming pits that are difficult to detect until failure occurs.
- Under-deposit Corrosion: Biofilms can trap particles and corrosion products, creating deposits that shield areas from corrosion inhibitors and increase metal loss beneath the surface.
- Reduced Heat Transfer Efficiency: Biofilms act as insulators, reducing the efficiency of heat exchangers and increasing energy costs.
- Inhibitor Ineffectiveness: Thick biofilms can prevent corrosion inhibitors and biocides from reaching the metal surface, making chemical treatments less effective.
Prevention and Treatment
Managing biological contamination is essential for effective corrosion control. At Fact, we use a multi-pronged approach:
- Regular Monitoring: Using microbiological testing and corrosion probes to detect early signs of MIC.
- Biocide Programs: Targeted use of oxidizing and non-oxidizing biocides to control microbial populations.
- Biofilm Disruption: Employing biodispersants and mechanical cleaning to remove established biofilms.
System Design & Maintenance: Minimizing stagnant zones, improving flow, and conducting regular inspections.
How to Prevent MIC – Final Thoughts
Corrosion in industrial water systems is rarely due to a single factor—and biological contamination is a hidden threat that deserves serious attention. By understanding how microorganisms interact with your system, you can prevent costly damage and ensure your water treatment processes remain efficient and reliable.
At Fact, we provide expert corrosion and microbial control solutions tailored to your system’s unique needs. Contact us today to learn how we can help you protect your infrastructure from the inside out.