Microbiological Influenced corrosion (MIC)
Microbiological Influenced Corrosion, commonly known as simply “MIC,” is an extremely rapid form of local corrosion initiated or accelerated by microorganisms. It is a well-recognized phenomenon in industries in which any form of metal is in at least temporary contact with water.
In maritime and offshore environments, it is widely spread due the combined influences of seawater and the active role of marine microorganisms in corrosion processes.
MIC diagnosis is a process of collecting evidence from different interactions between microorganisms, the environment and the material. The process of MIC diagnosis cannot be generalized and must follow a case-by-case approach, including:
- MIC-related material failure analysis
- Microbiological analysis
- Chemical analysis
The probabilities of wrong interpretations increase when any of these diagnostic approaches are missing. At Endures, we combine all necessary tools for comprehensive MIC investigations.
Visual and microscopic “failure” examination
The physical relationship between material damage and microorganisms is key to diagnosing MIC. Also, certain damage features at the surface (e.g., shape of pits, pits inside pits, microbial cell-shaped pits, etc.) can be indicative in many cases of MIC and provide an important clue in the diagnostic process. Our laboratory facilities include a wide variety of microscopes, including:
- Fluorescence microscopy
- Atomic force microscopy
- Scanning electron microscopy
In many circumstances growth-based methods are a good indicator of potentially corrosive microbial activity. The Endures lab is equipped with all necessary tools to reproduce the growth of MIC-related organisms, such as:
- SFB – Slime-forming bacteria
- APB – Acid producing bacteria
- IOB/IRB – Iron-oxidizing and iron-reducing bacteria
- SOB – Sulfur-oxidizing bacteria
- SRB – Sulfate-reducing bacteria
- MnO – Manganese-oxidizing bacteria
- Several other MIC-inducing groups, such as nitrate-reducing bacteria, fungi, among others
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Molecular-based detection methods
At Endures we complement our microbial growth tests with determinations at the genetic level (DNA), which by-pass the need for microbial cultivation.
To do this, we use the quantitative polymerase chain reaction technology (qPCR). The qPCR system at our laboratory can detect and quantify corrosive microbial activity for several corrosion-inducing microorganisms. Additionally, in cooperation with our partners, we have access to the latest technology on Next Generation Sequencing (NGS) which facilitates a wider insight into MIC population analyses.
The main advantages of molecular methods are:
- Speed – Hours instead of days compared with growth-based methods
- Unbiased – No selective pressure is applied, so even organisms that are not able to grow or are outcompeted by other species in laboratory conditions can be determined
- Ideal for extreme environments – Microorganisms growing in extreme environments are difficult to grow in the laboratory
Mitigation and prevention of MIC
Once the corrosion problem is related to organisms with a reasonable certainty, then Endures can advise on mitigation possibilities:
- Advice on use of antimicrobials
- Biocide testing
- Advice on design and protective measures
When required, Endures can test susceptibility of relevant organisms isolated from target environments to specific biocides, which takes into account application feasibility for our customers. With an appropriate mitigation measure in place, Endures can help you monitor the effectiveness of any applied treatment, including:
- Installation of corrosion racks coupled to full MIC failure analyses
- Advice on relevant online parameters to be monitored
MIC in extreme environments
Resource scarcity and technology developments are continually pushing industrial activities into more extreme environments of temperature, pressure and harsh chemical conditions. Microorganisms have demonstrated a huge capacity to adapt and be active in such environments. Here at Endures, we are focusing our research on developing advanced expertise and tests facilities for MIC occurring in these extreme environments.