MICROBIAL CORROSION
- Bacterial corrosion
- Bio-corrosion
- Microbiologically influenced corrosion
- Microbially induced corrosion (MIC)
Predominant Types of Bacteria
Acids Produced By Microbes
How to identify MIC
Control Measures
Coating the metal surfaces
Cathodic protection
Use of biocides
Bromine
Effective against bacteria and algae; oxidizing; wide pH range
Chlorine dioxide
Effective against bacteria, in a lesser extent against fungi and algae, oxidizing, pH-independent
Chlorine
Effective against bacteria and algae, oxidizing, pH dependent
Insulating pipe surfaces from the environment by impervious coatings is one of the most practical preventive measures
- Low Nutrient Bacteria (LNB)
Microbes/bacteria that grow in environments, such as potable water, with very low concentrations of nutrients
- Anaerobic Bacteria
Bacteria that grow in the absence of abundant free oxygen
- Sulfate-Reducing Bacteria (SRB)
Bacteria that converts sulfate ions to sulfides (including hydrogen sulfide). These bacteria can grow in low oxygen environments
- Iron-Related Bacteria (IRB) Bacteria that converts soluble iron ions (ferrous) to insoluble iron ions (ferric)
- Aerobic Bacteria
Bacteria that grow in the presence of free oxygen
Organic Acids
- Low molecular weight
- Acetic acid
- Lactic acid
- Butyric acid
- High molecular weight
- Acidic polysaccharides
Inorganic Acids
- Sulfuric acid
- Nitric acid
- Carbonic acid
Chemical-Test directly for pH, organic acids and test indirectly (test by products) for iron sulfide.
Biological - The most common are the MIC Field Kit and/or microbiological culturing
Metallurgical - Visually identify shiny metal underneath corrosion products
