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Microbial Contamination

How it works

About Microbial Contamination

Unique Flow Path Design of De-Bug

Maximising Magnetic Flux Density


a single cell weighing
one millionth
of a gram
can grow to
a biomass
of slimy algae weighing 10 kilograms
(22 pounds)
within 24 hrs

Growth in Fuels and Oils

Microbial contamination of petroleum products is a serious problem in the marine industry. Many bacteria, moulds and yeasts are able to degrade hydrocarbons and yet more are able to feed on the intermediate by-products of the degradation. Given the right conditions, a single cell weighing one millionth of a gram can grow to a biomass of slimy algae weighing 10 kilograms (22 pounds) within 24 hours.

The Effects of Microbial Contamination

The physical effects of microbiological contamination are the formation of biological sludges, biofilms (slimes) and surface or interfacial scums. These mainly occur in the fuel tank and also manifest themselves as material which block filters.

A number of microbial and chemical processes produce corrosive by-products including strong organic acids and sulphides. These can degrade protective coatings such as paints, rubber, some plastics and metal oxide films as well as destroy or inactivate chemical corrosion inhibitors and cause hydrogen embrittlement of metals. Black deposits on copper or copper containing alloys in pipe work and bearings as well as pitting are evidence of microbial induced corrosion.

Engines rely on high quality fuel that has been properly filtered and separated (from water), with no flow restrictions, to achieve proper atomisation, combustion, engine performance and fuel efficiency. Fuel that is infected with bacteria is not reliable and there are many and varied consequences of using contaminated fuel.

These include:

1. encouraging growth of further contamination
2. fuel filter clogging and blockage
3. coalescer malfunctions
4. engine wear due to variations in fuel flow
5. corrosion of the fuel system
6. corrosion of engine fuel injectors
7. damage to in-line instruments

Engine fuel injection equipment and fuel pumps are most susceptible to the effects of microbial contamination resulting in corrosive damage.

Ultimately, performance suffers and fuel consumption and maintenance costs increase, but perhaps the most critical concern is the real potential for blockages in the fuel system which cause engine failure while underway - with potentially devastating consequences.

Using Biocides

Biocides are frequently used to treat severe contamination, however many of them are hazardous chemicals and require careful handling. Although some are marketed as being "environmentally friendly", many are harmful to the environment and waste disposal contractors may need to be called in if waste containing dead microbes and biocide are to be removed.

Adding biocides to the fuel system can actually cause more problems. The fallout of dead cells collecting on the bottom of the tank forms a sludge material that can still find its way into the fuel system, clogging fuel lines and filters, potentially leading to performance problems and possibly engine damage. This can be especially true in rough weather when the contents of the tank are effectively shaken into suspension.
Furthermore, over time biocides lose their effectiveness as microbes build up immunity to the chemicals. Occasional dosing can actually accelerate this action and some owners have reported bio-mass growth in systems despite regular treatments with biocides.
Thus biocides can actually contribute to the problems of microbial contamination; not only by causing a large amount of sludge to build up but by also giving a crew a false sense of security.

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