Microbiological corrosion is promoted by scum forming at the bottom of a fuel tank in contact with metal. Which observation is correct?

Microbiological corrosion is promoted by scum forming at the bottom of a fuel tank in contact with metal. Which observation is correct?

• A. Scum layer at bottom in contact with metal
• B. Absence of moisture
• C. Dry air exposure
• D. High vacuum

Answer: (A)

Microbiological corrosion happens when a biofilm forms at the metal–water interface, creating a localized, nutrient-rich environment that keeps microbes in direct contact with the metal. A slime or scum layer at the bottom of a fuel tank signals that water has collected there and microbes are thriving in that near-metal niche. This biofilm concentrates microbes and their metabolic byproducts right at the metal surface, accelerating corrosion where the metal and scum meet. The observation that best fits this is the presence of a scum layer at the bottom in contact with the metal, because it shows both moisture availability and a habitat for microbial activity right at the metal surface. The other options describe conditions that would limit microbial growth—no moisture, dry air, or high vacuum—so they would not promote microbiological corrosion.

Microbiological corrosion happens when a biofilm forms at the metal–water interface, creating a localized, nutrient-rich environment that keeps microbes in direct contact with the metal. A slime or scum layer at the bottom of a fuel tank signals that water has collected there and microbes are thriving in that near-metal niche. This biofilm concentrates microbes and their metabolic byproducts right at the metal surface, accelerating corrosion where the metal and scum meet.

The observation that best fits this is the presence of a scum layer at the bottom in contact with the metal, because it shows both moisture availability and a habitat for microbial activity right at the metal surface. The other options describe conditions that would limit microbial growth—no moisture, dry air, or high vacuum—so they would not promote microbiological corrosion.