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Co-Processing Lignocellulosic Biomass and Sewage Digestate by Hydrothermal Carbonisation: Influence of Blending on Product Quality

Authors :
Kiran R. Parmar
Aaron E. Brown
James M. Hammerton
Miller Alonso Camargo-Valero
Louise A. Fletcher
Andrew B. Ross
Source :
Energies, Vol 15, Iss 4, p 1418 (2022)
Publication Year :
2022
Publisher :
MDPI AG, 2022.

Abstract

Hydrothermal carbonisation (HTC) can be integrated with anaerobic digestion (AD) for the treatment of digestate, resulting in a solid hydrochar or bio-coal and a process water, which can be recirculated back into AD to produce biogas. The properties of digestate-derived hydrochars do not lend themselves to producing high quality bio-coal and blending with lignocellulosic feedstocks can improve its properties. This study investigates the co-processing of sewage sludge (SS) digestate with three lignocellulosic biomass (grass, privet hedge, and woodchip). The calorific value of the resulting bio-coal is increased following co-processing, although feedstock interactions result in non-additive behaviour. The largest increase in calorific value was observed for co-processing with woodchip. There is evidence for non-additive partitioning of metals during co-processing resulting in only moderate improvements in ash chemistry during combustion. Co-processing also effects the composition of process waters, influencing the potential for biogas production. Experimental biomethane potential (BMP) tests indicate that grass clippings are the most suitable co-feedstock for maintaining both calorific value and biogas production. However, above 200 °C, BMP yields appear to decrease, suggesting the process water may become more inhibitory. Co-processing with wood waste and privet hedge produce the higher CV bio-coal but significantly reduced BMP.

Details

Language :
English
ISSN :
19961073
Volume :
15
Issue :
4
Database :
Directory of Open Access Journals
Journal :
Energies
Publication Type :
Academic Journal
Accession number :
edsdoj.2ce1de4d9801447b9cf1ba8a125176dd
Document Type :
article
Full Text :
https://doi.org/10.3390/en15041418