Fuel System Microbiology Basics (Part 1)


It is no secret the damage unchecked fuel systems incur due to microbial contamination. Product loss, liability increases and Microbial Influenced Corrosion (MIC). MIC is responsible for significant financial cost. According to NACE International, corrosion within the fuel industry accounts for over $7 Billion in annual losses.

We will be discussing the adverse roll microorganisms play in damaging fuel systems. The following summary is meant to be an overview. Please note that this is not an attempt to cover every aspect, but only highlight major problems found today in fuel systems. Let’s start with the basics.

There are three microorganisms commonly found in fuel systems: algae, bacteria and fungi. Algae when found in fuel does not appear to be a major contributor to fuel system damage when compared to bacteria and fungi. Yeast and molds are the most common fungi found. Fungi often observed in the water-fuel interfaces on the bottom of tanks form a thick membrane or film evident in bottom samples. Bacteria are single-cell microorganisms found everywhere. Three broad types are relevant to the fuel industry: aerobes, anaerobes and facultative anaerobes.

Aerobic bacteria require oxygen to survive. Oxygen found commonly in water-fuel interfaces and condensation provide a ready source. Anaerobic bacteria cannot tolerate oxygen and will likely die; others can remain dormant. The most common and damaging anaerobe found in fuel systems is Sulphate Reducing Bacteria (SRB). We will talk about this specifically in later posts. Facultative anaerobes can survive in both oxygen and anoxic (without oxygen) environments.

The most important thing to realize is that no one single microbe is causing the problems associated with fuel contamination and fuel system damage. Microbes work in consortia (communities working together). Biodeterioration (the detrimental change to materials due to bioorganic activity) results from microbes working together. Over the next few months, our posts will describe in more detail how microbes interact, contaminate fuel and damage fuel systems.