Diesel Fuel Improvers and Their Effect on Microbial Stability of Diesel/Biodiesel Blends

Additives that enhance properties, such as cetane number or cold flow, are introduced in diesel-biodiesel blends in order to upgrade its performance as well as to aid its handling and distribution. Furthermore, in order to protect the engine and fuel operating system equipment, diesel fuel may be treated with corrosion inhibitors and detergents. However, additives could also have an impact on other parameters beyond those that they are intended to boost. In the present study the effect of diesel fuel improvers on fuel’s microbial stability is examined. An additive-free ultra low sulfur diesel (ULSD) was blended with Soybean Fatty Acid Methyl Esters (FAME) and the resulting blend was treated separately with a series of commercially available diesel fuel additives. Specific products belonging to the groups of cold-flow improvers, cetane improvers, metal deactivators and corrosion inhibitors were employed and were added both at the recommended treating rate as well as in a range of concentrations (1000, 250 and 500 ppm). Following to this, the impact of those agents on microbial proliferation in diesel fuel was studied under certain testing protocols for detecting and evaluating substances that could inhibit fuel biodeterioration. Overall, the results demonstrate that certain additives primarily added to diesel fuel in order to improve its performance contain substances that are non-supportive to bacterial proliferation.