It is almost impossible to eradicate water and microbiological contamination from fuel storage tanks and systems used for gas oil, Derv, kerosene and petroleum spirit. The resultant brown or black slimes and sludges are a major cause of costly tank corrosion, filter blockages, pump failure and poor performance. Treatment can provide the most effective and economical solution to Fuel Spoilage.

It is well known that contamination in the form of bacteria or fungal growth exists in most middle distillate fuel oil storage tanks down stream from the refinery. The remedies are less well known. The result of contamination can be simply poor performance of engines or oil burners or, more seriously, partial blockage of fuel lines and fuel filters due to the accumulation of black sludge and slimes in the bottom of the fuel storage tank. The catastrophic failure of the engines or burners, acidic corrosion of fuel pumps, injectors and storage tanks can cause fatal consequences and is certainly expensive.

Causes of Contamination

Bacterial & Fungal contamination often occurs between downstream stages.
Airborne bacteria and fungi can readily enter fuel tanks through air vents, and multiply very fast in this bottom water phase. These micro-organisms do in fact need the presence of water in order to multiply, but given a very small initial quantity, they can actually produce their own supply of water by feeding off the fuel. This is particularly likely to happen in diesel and gas oil tanks where it is impossible to exclude water altogether. Water enters these tanks by various methods, such as through condensation, rain water or ground water leakage or even with the fuel delivery.

Microbiological growth will often produce black sludge but the worst type of micro-organisms are the sulphate reducing bacteria (SRBs). These produce acidic by-products which can corrode fuel tanks and systems, with the potential to cause severe damage.

There is also some evidence that the incidence of contamination is increasing. Though the reasons for this are not clear, the availability of lower grade fuel in certain locations is being put forward. Local weather conditions are often overlooked as the cause of this contamination producing condensation in cold periods followed by rapid growth in following warm periods.

There are usually high levels of awareness of the cause and solution to microbiological contamination amongst personnel in the oil distribution chain. On the other hand the general public, and service industries engaged in oil burner and engine maintenance are usually unable to diagnose the problem without expert help.