Integrated Approach to Spent Coffee Grounds Valorization in Biodiesel Biorefinery

Valentína Kafková (), Róbert Kubinec, Jozef Mikulec, Miroslav Variny, Petra Ondrejíčková, Aleš Ház and Adriana Brisudová
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Valentína Kafková: Association “Energy 21”, 920 41 Leopoldov, Slovakia
Róbert Kubinec: Department of Analytical Chemistry, Faculty of Natural Sciences, Comenius University in Bratislava, 842 15 Bratislava, Slovakia
Jozef Mikulec: VÚRUP, a. s., 820 03 Bratislava, Slovakia
Miroslav Variny: Institute of Chemical and Environmental Engineering, Faculty of Chemical and Food Technology, Slovak University of Technology in Bratislava, 812 37 Bratislava, Slovakia
Petra Ondrejíčková: Centrum Výskumu a Vývoja, s.r.o., Envien Group, 920 41 Leopoldov, Slovakia
Aleš Ház: Department of Wood, Pulp and Paper, Faculty of Chemical and Food Technology, Slovak University of Technology in Bratislava, 812 37 Bratislava, Slovakia
Adriana Brisudová: ENVIRAL a. s., Envien Group, 920 41 Leopoldov, Slovakia

Sustainability, 2023, vol. 15, issue 7, 1-17

Abstract: With the increasing consumption of coffee beverages, an increased amount of food waste—spent coffee grounds (SCG)—is generated and disposed into landfills or combusted in incinerators. SCG are characterized as a highly polluting substance with partial toxicity due to the presence of caffeine, tannins, and polyphenols. It also contains 15% of oil on average, and its potential for biodiesel production is thus considerable. The aim of the presented work is to evaluate the possibility and technical potential of biodiesel production from the SCG oil (SCGO) by esterification and transesterification reaction. According to the characterization of the studied SCGO, this stream must be adjusted and purified to be utilized in the existing biodiesel production plant. Fatty acids (FA) represent 85.85% of the SCGO, with two dominant FAs—linoleic and palmitic acids. The necessity of removal and disposal of unsaponifiable matter, which accounts for 15% of the SCGO content, must be highlighted when producing biodiesel from the SCG. The objective of this research was the comparison of different biodiesel production processes, where a two-step transesterification process has been identified as the most successful method for biodiesel production from the SCGO with the highest ester content of 89.62% and the lowest content of unsaponifiable and unidentified matter in the final product. The novelty of the analyses is a characterization of the d unsaponifiable matter present in the SCGO, and the article highlights the importance of progression to be considered when evaluating the technical potential of the SCG biodiesel production integrated into a biorefinery. Nevertheless, the SCG biodiesel can contribute to fulfilling the mandatory share of advanced biofuel in the fuel energy mix given by national legislation and contribution to the circular economy approach of biorefineries.

Keywords: spent coffee grounds; coffee waste; advanced biodiesel; transesterification; coffee oil; waste valorization (search for similar items in EconPapers)
JEL-codes: O13 Q Q0 Q2 Q3 Q5 Q56 (search for similar items in EconPapers)
Date: 2023
References: View references in EconPapers View complete reference list from CitEc
Citations: View citations in EconPapers (1)

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