Two step esterification-transesterification process of wet greasy sewage sludge for biodiesel production.
Sewage sludge generated in municipal wastewater treatment plants was used as a feedstock for biodiesel production via esterification/transesterification in a two-step process. In the first esterification step, greasy and secondary sludge were tested using acid and enzymatic catalysts. The results indicate that both catalysts performed the esterification of free fatty acids (FFA) simultaneously with the transesterification of triacylglycerols (TAG). Acid catalyst demonstrated better performance in FFA esterification compared to TAG transesterification, while enzymatic catalyst showed the ability to first hydrolyze TAG in FFA, which were esterified to methyl esters. In addition, FAME concentration using greasy sludge were higher (63.9% and 58.7%), compared with those of secondary sludge (11% and 16%), using acid and enzymatic catalysts, respectively. Therefore, only greasy sludge was used in the second step of alkaline transesterification. The alkaline transesterification of the previously esterified greasy sludge reached a maximum FAME concentration of 65.4% when using acid catalyst.
Scientific and Technological Bioresources Nucleus, University of La Frontera, Casilla 54-D, Temuco, Chile.
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Urrutia
Laboratory of Oils and Fats, Department of Agro-food Industry, Food and Nutrition, College of Agriculture "Luiz de Queiroz" (ESALQ), University of São Paulo, Piracicaba, São Paulo, Brazil.
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Sangaletti-Gerhard
Scientific and Technological Bioresources Nucleus, University of La Frontera, Casilla 54-D, Temuco, Chile; Department of Chemical Engineering, University of La Frontera, Casilla 54-D, Temuco, Chile.
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Cea
Scientific and Technological Bioresources Nucleus, University of La Frontera, Casilla 54-D, Temuco, Chile.
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Suazo
Department of Agriculture, Microbiology Division, University of Naples Federico II, via Università 100, 80055 Portici Naples, Italy.
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Aliberti
Scientific and Technological Bioresources Nucleus, University of La Frontera, Casilla 54-D, Temuco, Chile; Department of Chemical Engineering, University of La Frontera, Casilla 54-D, Temuco, Chile; Centre for Biotechnology & Bioengineering (CeBiB), Casilla 54-D, Temuco, Chile. Electronic address: rodrigo.navia@ufrontera.cl.
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Navia
D056804:Biofuels; D002384:Catalysis; D004951:Esterification; D004952:Esters / Q000737:chemistry; D005230:Fatty Acids, Nonesterified / Q000737:chemistry; D012722:Sewage / Q000737:chemistry*; D014280:Triglycerides / Q000737:chemistry; D014865:Waste Disposal, Fluid / Q000379:methods
D056804:Biofuels; D004952:Esters; D005230:Fatty Acids, Nonesterified; D012722:Sewage; D014280:Triglycerides
In situ esterification; Lipase; Methyl ester; Sewage sludge; Transesterification