Characterization of Raw and Biochar Polymer Sludge (PS) for Potential Use in Co-Firing: Comparative Analysis with Biochar EFB and Melawan Coal

The rising demand for sustainable solid fuels has driven interest in converting industrial waste materials into biochar for co-firing applications. This study examines the viability of polymer sludge (PS) as a biochar feedstock and evaluates its efficacy in comparison to empty fruit bunch (EFB) and Melawan coal. Pyrolysis was performed at 300 °C in purging of nitrogen gas in tube furnace, and the resultant biochar were assessed by proximate, ultimate, calorific value, and energy densification (ED) assays. Raw PS demonstrated a low calorific value of 10.91 MJ/kg and a high ash content of 32.74 wt.%; however, pyrolysis improved its energy content to 14.04 MJ/kg, reflecting a 29 % increase in energy improvement and an energy density (ED) of 1.29. biochar EFB exhibited enhanced performance with a calorific value of 24.41 MJ/kg (40 % energy improvement with ED = 1.40), nearing the energy density of Melawan coal (19.58 MJ/kg). Although biochar PS exhibits only a slight improvement over biochar EFB, the findings indicate that PS can be refined into an additional co-firing fuel with the potential for partial coal replacement. Nonetheless, its substantial ash content, minimal fixed carbon, and increased oxygen levels suggest that additional enhancement by higher-temperature pyrolysis, ash reduction, and co-blending is necessary to improve its fuel quality. In summary, biochar PS offers a viable method for waste valorisation and enhances sustainable energy output when managed correctly.