(339d) Biodiesel From Sewage Sludge

Primary and activated sludges generated in wastewater treatment facilities consist of a variety organic matter and microorganisms. The lipids in this sludge could be used to generate biodiesel, a mixture of fatty acid methyl esters that conforms to the ASTM D6751 standard. Biodiesel is sold commercially as a blend with petroleum diesel. In 2006 biodiesel production was approximately 80 million gallons. In this work, primary and secondary sludges were collected from a municipal wastewater treatment plant located in Tuscaloosa, AL. After collection, sludges were concentrated by centrifugation, and dried using a freeze dryer. Sludges were also homogenized prior to each experiment. Lipids in dry sludge (~5% moisture) were converted to biodiesel by in-situ transesterification. In-situ transesterification combines extraction and transesterification into one step. Gas chromatography was used to analyze the fatty acid methyl esters in the sample. The biodiesel generated from the sludges was also tested for ASTM compliance. ASTM testing included viscometry, flash point, Cu-corrossion test, cloud point, C resident, distillation, and S analysis. It is estimated that wastewater treatment facilities could provide approximately 800 million gallons of feedstock for biodiesel production. The presentation will include an economic analysis of the generation of biodiesel from sewage sludge.