Enhancement of larger empty fruit bunch particles to biochar in view of biocircularity. The case of palm oil industry in Cameroon

Abstract

The valorisation of agriculture wastes remains a major challenge. Hence, remarkable quantities of oil palm empty fruit bunches (EFB) generated yearly from the Cameroon oil palm industry are mostly dumped, inflicting unhealthy environmental pollution that has provoked massive criticism. This study aimed to investigate the unprecedented thermochemical enhancement of larger (150 mm) sized EFB particles into solid biofuel and characterise it in view of implementing the bio-circularity model in the industry. The EFB were pyrolyzed in an off-grid reactor having an internal centralised heater and lagged outer walls under controlled temperature and retention time. At 300 °C and retention time of 60 min, biochar yield of 53.5 % wt. was obtained with a higher heating value (HHV) of 23.00 MJ/kg, determined by bomb calorimetry. Proximate analysis on the biochar revealed moisture content of 2.54 %, volatile matter 39.87 %, fixed carbon of 51.95 % and ash content of 5.64 % composed of 19.5 % silica. These values were within acceptable range for biofuels suitable for thermal application, in conformity with ISO standards of quality solid biofuel. The bio-circularity model focuses on wastes identification, upcycling, and re-utilisation; thus, its implementation would enable waste minimisation, industry running cost reduction, mitigation of environmental pollution, and global climate change. A life cycle assessment conducted on the valorisation of EFB to biochar through slow pyrolysis indicated an insignificant greenhouse gas emission of 0.0478 kg CO₂ eq. kg⁻¹ of EFB utilised, compared to about 2.75 kg CO₂ eq. from the combustion of 1 kg of fossil fuel like methane. This research establishes appropriate conditions for EFB transformation into sustainable renewable biochar which has various potential uses: bio-fertilizer, adsorbent, biofuel, etc. Other by-products like silica may be useful in the chemical industry while the green circular process would create more economic value to the industry and the community.