CHARACTERIZATION OF FUNGAL CONTAMINANTS IN B20 BIODIESEL STORAGE TANKS AND THEIR EFFECT ON FUEL COMPOSITION
Abstract
The liquid transportation fuel B20 biodiesel is an 80:20 blend of petroleum-derived
ultra-low sulfur diesel (ULSD) and biodiesel. Although B20 biodiesel represents a
fungible fuel with a reduced carbon footprint compared to petroleum diesel, it is more
susceptible to microbial contamination and biodegradation. The research described in
this thesis characterized the numerically abundant fungi responsible for fouling in B20
biodiesel storage tanks. This work also investigated the effect of microbial
contamination and proliferation on B20 biodiesel composition. Fungi from the genera
Wickerhamomyces and Byssochlamys were abundant in the B20 storage tanks that were
monitored in this study. Members of the yeast Wickerhamomyces anomalus SE3 and the
filamentous fungus Byssochlamys sp. SW2 that represent the major taxa in B20 storage
tanks were isolated and characterized for their ability to degrade components of B20
biodiesel. Both Wickerhamomyces anomalus SE3 and Byssochlamys sp. SW2 were able
to use B20 biodiesel as sole carbon and energy source. We show that the presence of
Byssochlamys sp. SW2 can alter the composition in B20 biodiesel in storage tanks, and
we offer a model for predicting the severity of biodegradation. Byssochlamys sp. SW2
preferentially degraded palmitic and linoleic acid methyl esters, and our in situ model
supports the hypothesis that palmitic and linoleic acid methyl esters are the most
susceptible components to biodegradation. We suggest the use of alternative feedstocks
containing less palmitic and linoleic acid for B20 biodiesel production to increase fuel
stability in storage tanks.
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- OU - Theses [2217]