Microbiologically Influenced Corrosion (MIC) Testing
     Slime Forming     Nitrifying     Sulfate reducing     Iron bacteria

Special Pathogens Laboratory provides water treaters with microbiologically influenced corrision (MIC) testing. In addition to Legionella and other waterborne pathogens, SPL can identify nuisiance bacteria that create slime and corrosion in industry water systems, cooling towers and boilers.

Slime Forming

• Bacteria in the genera Serratia, Chromobacterium, Janthinobacterium
• Produces copious amounts of slime without metabolizing iron
• First symptom is increased turbidity followed by changes in taste, odor or color
• Generates thickest slime formations under aerobic conditions
• Under harsh environmental conditions slime layers get thicker
• Can cause serious engineering problems
• Reduces hydraulic or thermal conductivity and water quality
• Determine the potential for exposure within high risk areas to waterborne pathogens such as multi-drug resistant strains of Pseudomonas, Stenotrophomonas and Acinetobacter

Nitrifying

• Bacteria in the genera Nitrosococcus, Nitrosomonas, and Nitrobacter
• Bacteria recycle organic nitrogenous materials from ammonia to nitrates
• Aggressive nitrifiers produce high concentrations of nitrates
• Aggressive nitrifying bacteria in water may indicate stages of aerobic degradation of nitrogen-rich organic matter
• Can indicate water may have been polluted by nitrogen-rich organics from compromised septic tanks, sewage systems, iindustrial and hazardous waste sites
• Potential health risk, particularly to infants who haven’t developed tolerance to nitrates

Sulfate reducing

• A group of anaerobic bacteria that generate hydrogen sulfide (H2S) belonging to the genera Desulfobacterium, Desulfobacter, and Desulfovibrio
• Difficult to detect: anaerobic and grows deep within biofilms
• Sulfate reducing bacteria may not be present in free-flowing water over the site of the fouling
• Causes significant problems in water ranging from “rotten egg” odors to blackening equipment, slime formations, and initiates corrosive processes

Iron bacteria

• Examples include: Gallionella, Crenothrix, Sphaerotilus, Siderocapsa, and Thiobacillus ferroxidans
• Difficult to enumerate: subdivided into several groupings (e.g., iron-oxidizing and iron-reducing bacteria)
• Oxidize iron producing thick slime
  
• Taste and odor problems and “red water” are common symptoms
• Function under different reduction-oxidation (redox) conditions and use a variety of substrates for growth