Samuel Nketia Boateng

Mechanical pre-treatment can improve anaerobic digestion of lignocellulosic residues, but the effect of rice husk (RH) particle size during co-digestion with cow paunch content has received limited attention. This study evaluated whether smaller mechanically milled RH particles increase methane production during batch co-digestion with cow paunch content. Rice husk was milled and separated into four particle-size fractions: 0–125 µm (F1), >125–250 µm (F2), >250–500 µm (F3), and >500–1180 µm (F4). Batch biomethane potential assays were conducted under mesophilic conditions for 126 days using cow paunch content as inoculum and co-substrate. Particle-size distribution, substrate composition, cumulative methane yield, biodegradability index, pH, volatile solids, and total solids removal were assessed. F1 produced the highest cumulative methane yield (311 ± 2.7 mL CH ₄ /g VS), followed by F2 (289 ± 2.5 mL CH ₄ /g VS), F4 (262 ± 9.08 mL CH ₄ /g VS), the control (230 ± 4.3 mL CH ₄ /g VS) and F3 (134 ± 0.3 mL CH ₄ /g VS). Relative to the control, F1, F2 and F4 increased methane yield by approximately 35%, 26% and 14%, respectively, whereas F3 showed lower conversion. The final digestate pH (7.39–7.62), volatile solids removal and biodegradability indices indicated stable digestion for most treatments. The findings support the hypothesis that RH particle-size reduction can enhance methane recovery during co-digestion with cow paunch content, although the F3 outcome indicates that particle size alone does not determine process performance. Thus, energy-use and cost assessments are needed before scale-up.

Ghana spends over $4000 (US dollars) annually managing municipal solid waste (MSW) with little improvement in regional sanitation. Energy demand in the country is also on the rise. Therefore, addressing waste problems via the waste-to-energy valorization approach is necessary for dual benefits. This paper thus seeks to comprehensively review Ghana's MSW's proximate and ultimate compositions for biological and thermochemical conversions. Studies between 2011 and 2024 were analyzed. The findings revealed that the organic fraction of Ghana’s MSW is currently about 10.47Kt per day. The proximate analysis reveals a moisture content from 13.55 – 61.9 %, volatile matter ranges from 6.24 - 80.25%, and the calorific value ranges from 14.96-21.46MJ/Kg. The ultimate analysis revealed that the carbon-to-nitrogen ratios range from 24.3-32.2, and the hydrogen content ranges from 5.53-22.8%. The sulphur and nitrogen contents were below 0.6 and 1.7% respectively. Approximately 2,534.65 GWh of electricity is estimated from the organic fraction. Ghana’s MSW is more suited for biochemical conversions.