Sequential Production of Lignin, Fatty Acid Methyl Esters and Biogas from Spent Coffee Grounds via an Integrated Physicochemical and Biological Process

Minjeong Lee, Minseok Yang, Sangki Choi, Jingyeong Shin, Chanhyuk Park, Si-Kyung Cho and Young Mo Kim
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Minjeong Lee: School of Earth Sciences and Environmental Engineering, Gwangju Institute of Science and Technology (GIST), Buk-gu, Gwangju 61005, Korea
Minseok Yang: School of Earth Sciences and Environmental Engineering, Gwangju Institute of Science and Technology (GIST), Buk-gu, Gwangju 61005, Korea
Sangki Choi: School of Earth Sciences and Environmental Engineering, Gwangju Institute of Science and Technology (GIST), Buk-gu, Gwangju 61005, Korea
Jingyeong Shin: School of Earth Sciences and Environmental Engineering, Gwangju Institute of Science and Technology (GIST), Buk-gu, Gwangju 61005, Korea
Chanhyuk Park: Department of Environmental Science and Engineering, Ewha Womans University, Seoul 03760, Korea
Si-Kyung Cho: Department of Biological and Environmental Science, Dongguk University, Goyang, Gyeonggi-do 10326, Korea
Young Mo Kim: School of Earth Sciences and Environmental Engineering, Gwangju Institute of Science and Technology (GIST), Buk-gu, Gwangju 61005, Korea

Energies, 2019, vol. 12, issue 12, 1-13

Abstract: Spent coffee grounds (SCG) are one of the lignocellulosic biomasses that have gained much attention due to their high potential both in valorization and biomethane production. Previous studies have reported single processes that extract either fatty acids/lignin or biogas. In this study, an integrated physicochemical and biological process was investigated, which sequentially recovers lignin, fatty acid methyl esters (FAME) and biogas from the residue of SCG. The determination of optimal conditions for sequential separation was based on central composite design (CCD) and response surface methodology (RSM). Independent variables adopted in this study were reaction temperature (86.1–203.9 °C), concentration of sulfuric acid (0.0–6.4%v/v) and methanol to SCG ratio (1.3–4.7 mL/g). Under determined optimal conditions of 161.0 °C, 3.6% and 4.7 mL/g, lignin and FAME yields were estimated to be 55.5% and 62.4%, respectively. FAME extracted from SCG consisted of 41.7% C16 and 48.16% C18, which makes the extractives appropriate materials to convert into biodiesel. Results from Fourier transform infrared spectroscopy (FT-IR) further support that lignin and FAME extracted from SCG have structures similar to previously reported extractives from other lignocellulosic biomasses. The solid residue remaining after lignin and FAME extraction was anaerobically digested under mesophilic conditions, resulting in a methane yield of 36.0 mL-CH 4 /g-VS added . This study is the first to introduce an integrated resource recovery platform capable of valorization of a municipal solid waste stream.

Keywords: spent coffee grounds; lignin; fatty acid methyl esters; organosolv; response surface methodology; anaerobic digestion (search for similar items in EconPapers)
JEL-codes: Q Q0 Q4 Q40 Q41 Q42 Q43 Q47 Q48 Q49 (search for similar items in EconPapers)
Date: 2019
References: View references in EconPapers View complete reference list from CitEc
Citations: View citations in EconPapers (6)

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