Synergistic enhancement of Wyodak coal bioavailability with sequential chemical treatment and fungal degradation

This study examined sequential chemical pretreatment and fungal degradation of Wyodak sub-bituminous coal with hydrogen peroxide followed by the fungal degradation with Paecilomyces variotii as the microbial agent. Coal was pretreated across varying concentrations (0.1–6 M) and subsequently assessed for bioavailability in aerobic biometer assays using carbon dioxide (CO 2 ) production as a quantitative proxy. The highest performance was observed at 3 M hydrogen peroxide, yielding cumulative CO 2 production of ~2.27 mmol/g coal and the maximum initial total organic carbon peaking at 107.37 mg C/g coal, with fungal degradation reducing total organic carbon (TOC) by ~74 mg C/g coal. Three-dimensional excitation-emission matrix fluorescence spectroscopy results showed an increased abundance of aromatic, humic, and fulvic-like organics post‑hydrogen peroxide pretreatment, which declined significantly during fungal treatment, confirming microbial consumption. These results demonstrate synergistic effect of sequential chemical pretreatment and fungal degradation in coal biodegradation, where CO 2 release, and TOC consumption serve as direct indicators of coal bioavailability and microbial activity. • H 2 O 2 facilitated Paecilomyces variotii greater access to coal-derived organics. • CO 2 production in biometers was used as a proxy for deciding coal bioavailability. • Moderate H 2 O 2 (0.5–1 M) converted more than 80 % of consumed TOC to CO 2 . • 3 M H 2 O 2 yielded highest CO 2 (~2.27 mmol/g coal) and TOC ~107.37 mg C/g coal. • 3-D EEM results confirmed microbes effectively consumed solubilized coal organics.