The Effect of Biochar Addition on the Biogas Production Kinetics from the Anaerobic Digestion of Brewers’ Spent Grain

Marta Dudek, Kacper Świechowski, Piotr Manczarski, Jacek A. Koziel and Andrzej Białowiec
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Marta Dudek: Faculty of Life Sciences and Technology, Institute of Agricultural Engineering, 37/41 Chełmońskiego Str., Wrocław University of Environmental and Life Sciences, 51-630 Wrocław, Poland
Kacper Świechowski: Faculty of Life Sciences and Technology, Institute of Agricultural Engineering, 37/41 Chełmońskiego Str., Wrocław University of Environmental and Life Sciences, 51-630 Wrocław, Poland
Piotr Manczarski: Department of Environmental Engineering, Faculty of Building Services, Warsaw University of Technology, Hydro and Environmental Engineering, 00-653 Warsaw, Poland
Jacek A. Koziel: Department of Agricultural and Biosystems Engineering, Iowa State University, Ames, IA 50011, USA
Andrzej Białowiec: Faculty of Life Sciences and Technology, Institute of Agricultural Engineering, 37/41 Chełmońskiego Str., Wrocław University of Environmental and Life Sciences, 51-630 Wrocław, Poland

Energies, 2019, vol. 12, issue 8, 1-22

Abstract: Biochar (BC) addition is a novel and promising method for biogas yield increase. Brewer’s spent grain (BSG) is an abundant organic waste with a large potential for biogas production. In this research, for the first time, we test the feasibility of increasing biogas yield and rate from BSG digestion by adding BC, which was produced from BSG via torrefaction (low-temperature pyrolysis). Furthermore, we explore the digestion of BSG with the presence BCs produced from BSG via torrefaction (low-temperature pyrolysis). The proposed approach creates two alternative waste-to-energy and waste-to-carbon type utilization pathways for BSG: (1) digestion of BSG waste to produce biogas and (2) torrefaction of BSG to produce BC used for digestion. Torrefaction extended the short utility lifetime of BSG waste turned into BC. BSG was digested in the presence of BC with BC to BSG + BC weight ratio from 0 to 50%. The study was conducted during 21 days under mesophilic conditions in n = 3 trials. The content of dry mass 17.6% in all variants was constant. The kinetics results for pure BSG (0% BC) were: reaction rate constant ( k ) 1.535 d −1 , maximum production of biogas ( B 0 ) 92.3 dm 3 ?kg −1 d.o.m. (d.o.m. = dry organic matter), and biogas production rate ( r ), 103.1 dm 3 ?kg −1 d.o.m. ?d −1 . his preliminary research showed that the highest ( p < 0.05) r, 227 dm 3 ?kg −1 d.o.m. ?d −1 was due to the 5% BC addition. This production rate was significantly higher ( p < 0.05) compared with all other treatments (0, 1, 3, 8, 10, 20, 30, and 50% BC dose). Due to the high variability observed between replicates, no significant differences could be detected between all the assays amended with BC and the variant 0% BC. However, a significant decrease of B 0 from 85.1 to 61.0 dm 3 ?kg −1 d.o.m. in variants with the high biochar addition (20–50% BC) was observed in relation to 5% BC (122 dm 3 ?kg −1 d.o.m. ), suggesting that BC overdose inhibits biogas production from the BSG + BC mixture. The reaction rate constant ( k ) was not improved by BC, and the addition of 10% and 20% BC even decreased k relatively to the 0% variant. A significant decrease of k was also observed for the doses of 10%, 20%, and 30% when compared with the 5% BC (1.89 d −1 ) assays.

Keywords: waste to carbon; waste to energy; biogas; methane; kinetics; torrefaction; biochar; brewer’s spent grain; anaerobic digestion; organic waste; waste management (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 (8)

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