Fuel contamination

Microbial contamination of distillate fuels is a longstanding problem. The microbes grow mainly on the fuel/water interface but can also stick to tank surfaces. The problems caused vary from filter blocking, tank corrosion, incorrect gauge readings to engine failure. The microbes involved include filamentous moulds, yeasts and bacteria. Predominant in aviation kerosene, is the mould Hormoconis resinae alongside a small number of bacteria. 


Most people have heard of the terms diesel bug, fuel contamination and mechanical breakdowns due to fuel contamination; some have probably personally experienced the effects of diesel bug bacteria and fungus in stored fuels or fuel storage vessels.

The shocking truth is that up to 80% of engine failure, to a greater or lesser degree, is the direct result of poor and contaminated diesel fuel. These failures can range from having disastrous consequences, being expensive to repair, or if you are lucky to just being darn outright inconvenient and a time waster for you. For example, the failures can result in:
In diesel fuels a much larger group of organisms are involved and the profile can change over time. The yeast Yarrowia lypolitica can become very important in heavy contamination cases. The problem has become increasingly severe with the introduction of biofuels and ultra-low sulphur diesels.

 Historically, identifying microbial contamination meant growing the organisms in a laboratory from fuel samples. Full analysis could take weeks to complete. A much quicker, on-site system was required.

The solution for this fuel contamination is the FUELSTAT resinae detection kit, which provides a semi-quantitative result in 10 minutes, was developed to detect contamination in aviation kerosene. It detects the presence of Hormoconis  resinae, which is the indicator species for this type of fuel. The development phase relied upon dozens of strains of the mould .Following the success of the original aviation variant a test kit for use in diesel was developed. 

For this fuel the test needed to be widened in scope to detect the other fungi, mainly yeasts, which are present plus aerobic bacteria. For the yeasts, a similar process was undertaken as for the aviation kit, using strains of the hydrocarbon-utilizing organisms.

The result is a 10 minute, onsite test that shows separate results for Hormoconis resinae, other yeasts and moulds and aerobic bacteria.

Research is now underway to produce a test for anaerobes that contaminate fuel storage systems. The main group consists of Sulphate Reducing Bacteria (SRBs) .

-Dixy