Abstract:
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Biodiesel expansion is currently limited due to high raw
material costs for its produc
tion. The potential of using
sludge from municipal wastewater treatment plants as an
alternative lipid feedstock for biodiesel production was
investigated. Experiments were conducted to evaluate the suit
ability of four different types of wastewater sludges for
biodiesel production. Lipids were extracted from primary, secondary, blended and stabilized sludge in a Soxhlet
extractor, using hexane as a solvent. Finally, the lipids were converted by acid catalysis transesterification into their
corresponding fatty acid methyl esters (FAMEs) - biodiesel
. Results indicated that among four sludge tested, primary
sludge achieved the greatest lipids and biodiesel yields. Th
e amount of extracted lipids
for primary sludge was 25.3%
compared to 21.9%, 10.1% and 9.1% (dry wt) for blended, stabilized and secondary sludge, respectively. The FAMEs
yields obtained in this study were 13.9%, 10.9%, 2.9% and 1% (dry wt) for primary, blended, secondary and
stabilized sludge, respectively. The estimation of annual biodiesel production based on the sludge generated in
WWTP of Reus was evaluated, showing that primary sludge consists of 87% of the total biodiesel among the
wastewater sludges. Gas chromatography analysis of th
e FAMEs revealed a similar fatty acids composition for all
sludge tested with a predominance of palmitic acid, stearic acid, oleic acid and linoleic acid.
Comparison of sludge
fatty acid profile with common biodiesel feedstocks showed their suitability for the production of biodiesel. |