• A low-cost open-access pyrolysis reactor is designed and constructed. • The reactor is suitable for laboratory-scale research, academic uses, and small-scale rural applications. • Design temperature of the reactor is 1000°C and experimentally validated temperature range is 450-700°C, using poultry manure, bones, rice husk, and wood flakes. • Detailed structural characterization of biochar produced at 450°C and 600°C. • Pyrolysis temperature significantly influences biochar yield, structure, and characteristics. Affordable, laboratory-scale pyrolysis reactors are scarce in developing countries, constraining decentralized biomass valorization. This study presents the engineering design, fabrication, and performance evaluation of a low-cost, slow pyrolysis batch reactor for academic research and small-scale rural applications. The reactor was modeled in SketchUp and fabricated locally, with a controlled operational design capacity of 1000°C, and an experimentally validated operating window of 450-700°C. Total construction cost was USD 557.02 and average biochar operating energy cost was USD 0.37 per kg, comparing favorably with other reported low-cost and pilot-scale systems. Four feedstocks, poultry manure, bones, rice husk, and wood flakes were converted into biochar with yields range of 14.8-43 wt.% depending on feedstock and temperature. Detailed characterization of poultry manure biochar at 450°C and 600°C revealed temperature-driven attenuation of oxygen-containing functional groups (Fourier-transform infrared spectroscopy, FTIR), a transition from amorphous to turbostratic carbon (X-ray diffraction, XRD), apparent surface roughening and pore enlargement (scanning electron microscopy, SEM; qualitative only), and a reduction in total heavy metal concentrations within International Biochar Initiative (IBI) threshold limits (inductively coupled plasma mass spectrometry, ICP-MS). The condensed liquid by-product was predominantly aqueous, indicating limited fuel potential. Short-term field application to two rice varieties produced statistically significant effects only on shoot and total biomass at the milking stage of BRRI Dhan-88. Combining multi-feedstock processing, condensate recovery, and integrated FTIR, XRD, SEM, and ICP-MS characterization within a single locally fabricated platform, the reactor offers a reproducible, low-cost pathway for biomass residue valorization in resource-constrained locations.
Mashiat et al. (Fri,) studied this question.