Influence of Microwave-Assisted Chemical Thermohydrolysis of Lignocellulosic Waste Biomass on Anaerobic Digestion Efficiency

Marcin Dębowski (), Marcin Zieliński, Anna Nowicka and Joanna Kazimierowicz
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Marcin Dębowski: Department of Environmental Engineering, Faculty of Geoengineering, University of Warmia and Mazury in Olsztyn, 10-720 Olsztyn, Poland
Marcin Zieliński: Department of Environmental Engineering, Faculty of Geoengineering, University of Warmia and Mazury in Olsztyn, 10-720 Olsztyn, Poland
Anna Nowicka: Department of Environmental Engineering, Faculty of Geoengineering, University of Warmia and Mazury in Olsztyn, 10-720 Olsztyn, Poland
Joanna Kazimierowicz: Department of Water Supply and Sewage Systems, Faculty of Civil Engineering and Environmental Sciences, Bialystok University of Technology, 15-351 Bialystok, Poland

Energies, 2024, vol. 17, issue 17, 1-22

Abstract: To date, microwave radiation has been successfully used to support the chemical hydrolysis of organic substrates in the laboratory. There is a lack of studies on large-scale plants that would provide the basis for a reliable evaluation of this technology. The aim of the research was to determine the effectiveness of using microwave radiation to support the acidic and alkaline thermohydrolysis of lignocellulosic biomass prior to anaerobic digestion on a semi-industrial scale. Regardless of the pretreatment options, similar concentrations of dissolved organic compounds were observed, ranging from 99.0 ± 2.5 g/L to 115.0 ± 3.0 in the case of COD and from 33.9 ± 0.92 g/L to 38.2 ± 1.41 g/L for TOC. However, these values were more than twice as high as the values for the substrate without pretreatment. The degree of solubilisation was similar and ranged between 20 and 28% for both monitored indicators. The highest anaerobic digestion effects, ranging from 99 to 102 LCH4/kgFM, were achieved using a combined process consisting of 20 min of microwave heating, 0.10–0.20 g HCl/gTS dose, and alkaline thermohydrolysis. For the control sample, the value was only 78 LCH 4 /kgFM; for the other variants, it was between 79 and 94 LCH 4 /kgFM. The highest net energy gain of 3.51 kWh was achieved in the combined alkaline thermohydrolysis with NaOH doses between 0.10 and 0.20 g/gTS. The use of a prototype at the 5th technology readiness level made it possible to demonstrate that the strong technological effects of the thermohydrolysis process, as demonstrated in laboratory tests to date, do not allow for positive energy balance in most cases. This fact considerably limits the practical application of this type of solution.

Keywords: microwave radiation; pretreatment; chemical thermohydrolysis; lignocellulosic biomass; anaerobic digestion; methane fermentation (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: 2024
References: View references in EconPapers View complete reference list from CitEc
Citations: View citations in EconPapers (1)

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