The diesel bug

Marine diesel is susceptible to the same problems of microbiological contamination as aviation kerosene. The main contaminant is also the same in both fuels - Hormoconis resinae (H. resinae). In aviation kerosene its called the "jet fuel fungus", in diesel its known as the "diesel bug".

Kerosene v Diesels

There is a difference, however, in the makeup of a typical profile of microbes in kerosene and diesels. In kerosene, H. resinae is present in about 95% of cases of contamination (along with a number of other bacteria and fungi). In diesel fuels H. resinae is only present in about 70% of cases of contamination (again, along with a number of other bacteria and fungi). In both liquids it is still the most dangerous organism (see our SCIENCE page), but it is not an indicator species as it is in kerosene.

Conidia's Fuelstat™ resinae kit for aviation kerosene detects contamination by looking for the activity of H. resinae. But that will only give a partial answer in diesel, so we have to look for the wider range of microbes to give the user a full, accurate answer. This process started in 2006.

Fuelstat marine kit

In 2006 Conidia commenced a research project to develop a kit that could provide an answer to the question "do I have microbial contamination in my marine fuel tank". The aim was to provide a simple to use and simple to interpret test, just like the aviation version, for the marine industry.

The aviation kit determines the levels of a compound produced by H. resinae when it is growing in fuel. From that level we determine the overall level of contmaniation from all sources and present the user with a simple readout stating that there is negligible contamination (there is always background activity), moderate contamination requiring action in terms of a biocide treatment or heavy contamination requiring a tank clean and a biocide treatment.

Accordingly, we decided to look at the life cycles of bacteria, yeasts and moulds in marine deisel and to raise antibodies against them or against byproducts of their activity when growing on hydrocarbons. Suitable antigens have been found and we have raised antibodies against them and are now in the process of translating those into an immunoassay test.

The exact layout of the test paddle has not yet been determined, but we hope to keep to two lateral flow devices, set to the boundaries between negigible and moderate and moderate and heavy contamination just as in our current kit. This will enable users to determine, accurately and quickly, the state of their tank.

Timescales

The pure research element of the project has now been completed and we move onto the development of the physical test itself. We hope to have a pre-production model out for testing in the next 5 - 6 months. This will be made available to our chosen collaborators for trialling. Anyone interested in being part of the trial should let us know using the "RESEARCH AND DEVELOPMENT" form on our contacts page.

Why should I worry about this?

Right from the beginning of our business life we have been approached by maintenance staff in the marine industry around the world stating that there is a simlar problem with contamination in diesels as there is in aviation kerosene. The problems that are caused are pretty much the same as well. The introduction of biofuels also seems to have had an effect on contamination, I.E. the number of cases are increasing. If you do not want blocked filters, slime or gunge in the tanks or corrosion to your tanks, then this new kit will be an important part of your monitoring regime.

Sulphate Reducing Bacteria (SRB)

A number of ship operators have discussed the issue of SRB contamination as well as the aerobic microbes that we detect normally. Tanks that contain a layer of slime or gunge on the bottom can become contaminated with these anaerobic bacteria. This appears to be a particular issue for naval vessels. Accordingly we have commenced research on these organisms and hope to have a fourth device, specifically aimed at SRBs, to be added to the three devices on the normal marine test, in 2009.

Keep in the loop

If you are interested in this topic please register in our contacts pages and we will keep you upto date with our progress.