Effects of coal fly ash pretreatment on fibre degradability and enhanced solid-state anaerobic digestion of lignocellulosic biomass
Author(s)
Grimes, Sue
Dewiandratika, Maryam
Smith, Stephen R
Type
Journal Article
Abstract
Coal fly ash (CFA) is an alkali waste generated in large quantities by the power generation industry. Lignocellulosic biomass (LB) is also a significant, globally problematic waste stream. Alkali pretreatment of LB by CFA, to reduce the recalcitrance of LB before anaerobic digestion (AD), has the potential to beneficially utilise both waste streams, provide a major renewable energy source, and reduce the risks of groundwater and soil contamination associated with CFA stockpiling. Controlled, laboratory microcosm experiments were conducted to examine the effectiveness of CFA as an alkali pretreatment and alternative to calcium oxide (CaO) and sodium hydroxide (NaOH) for AD of LB. The AD experiments were conducted under solid-state conditions at 15% total solids (TS) in 1 L borosilicate glass chemostat reactors. Coal fly ash pretreatment increased methane (CH4) yield by 93% and 39% compared to a water-pretreated control and equivalent alkalinity supplied by CaO alone (CaO pretreatment), respectively. In addition, CFA pretreatment, followed by AD, resulted in a twofold greater reduction in total fibre than CaO pretreatment, consistent with increased CH4 yield, hydrolysis rate (27%), and volatile solids (VS) removal (29%). A consistent increase in CH4 yield (32%) was also achieved when CFA was added after CaO pretreatment of LB, before AD. These results indicated the positive role of CFA in AD of LB extended beyond an alkali pretreatment effect.
Date Issued
2026-12-01
Date Acceptance
2026-07-31
Citation
Bioresource Technology, 2026, 461 (1)
ISSN
0960-8524
Publisher
Elsevier
Journal / Book Title
Bioresource Technology
Volume
461
Issue
1
Copyright Statement
Copyright © 2026 Elsevier. This is the author’s accepted manuscript made available under a CC-BY licence in accordance with Imperial’s Research Publications Open Access policy (www.imperial.ac.uk/oa-policy)
License URL
Publication Status
Accepted
Article Number
135555
Date Publish Online
2026-08-01