Fully quality controlled, validated analysis techniques are employed to test for microbial contamination in a wide range of samples. These tests can be conducted as part of a routine monitoring programme (eg to ensure absence of operational problems in fuels and oils, for final product compliance, quality assurance, raw materials quality), or as an investigation into operational problems (eg to identify contamination sources, auditing of production facilities).
Microbes can contaminate a wide range of petroleum fuels from heavy residual fuel oils to gasolines and cause very costly operational problems for suppliers, distributors and also end-users such as ship and smal/pleasure boat operators, haulage companies, bus and train operators and power generators. The problems include:
Increased water content
Microbial surfactants can stimulate the suspension of water in fuel causing it to become hazy and causing failure of fuel water separators.
Although the microbes need water to grow they need very little. In practice there is often sufficient water in the bottom of large storage tanks and even in the fuel tanks of road vehicles such as trucks and buses for some microbial growth to occur. The microbes tend to be most active at the interface between the water and fuel and also on internal tank and system surfaces. When the tank contents are disturbed, for example when the tank is refilled, the microbes become suspended in the bulk fuel where they cause fouling and may be passed on down the distribution chain to contaminate facilities downstream. Costs for decontaminating facilities are high. Prevention of problems by good housekeeping and regular monitoring is most definitely more cost effective than the "fire brigade treatment" of problems and the consequential losses due to system and equipment failures.
Growth of Sulphate Reducing Bacteria (SRB) in fuel tanks can also cause sulphide spoilage of fuels. The fuel becomes corrosive and will fail sulphide limit specifications.