Biotech Updates

Microbiological Stability of Biodiesel Blends

March 25, 2011
(complete access to journal article may require subscription or payment) http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6V24-525GWR2-
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Biodiesel fuel is said to be more hygroscopic (i.e. absorbs more water) compared to its counterpart fossil fuel. Since biodiesel is more biodegradable than petroleum diesel, the presence of water may allow undesirable microbial growth. Microbial growth in biodiesel can cause microbial fouling, fuel degradation, increased steel corrosion (in fuel storage tanks), and increased particle loads. Researchers from the Danish Technological Institute (Denmark) investigated microbial growth in incubated biodiesel-blend samples containing contaminated inoculated water.

Results of the study showed increased bacterial growth and activity in biodiesel blends compared to neat fossil diesel. The presence of anaerobic microorganisms, notably methanogens, sulfate-reducing bacteria and nitrate reducing bacteria, has been identified after incubation. The proportion of the biodiesel blend also affected anaerobic microbial activity and type of microbial community. A "large shift in the microbial community was observed when the biodiesel blend exceeded 10%–20%. This shift is said to have implications on biofilm corrosiveness, fuel spoiling and other effects which would need further study.

The full paper is published in the journal, Bioresource Technology (URL above).