Characterization of lignocellulosic crop residues for potential biogas production in Zimbabwe

Abstract Lignocellulosic biomass is considered to be an abundant and cheap resource for biogas plants. Efficient production of biogas from lignocelluloses depends upon its proximate composition. This short communication characterizes the proximate composition of locally available lignocellulosic crop residues (LCRs) – wheat straw, maize stover and soybean straw – as potential feedstocks for biogas production. Standard Methods for the Examination of Water and Wastewater were used to determine its physicochemical characteristics. Cellulose, lignocellulose and lignin content of the biomass were evaluated after Soxhlet ectraction. Results show that proximate composition varied widely amongst LCRs. Lignocellulosic crop residues were acidic in nature with high total nitrogen (TN) content, hence the need for some buffering in anaerobic digestion (AD). Soybean straw and wheat straw showed the highest pH and TN content, respectively. However, all LCRs contained more than 30% cellulose, suggesting their potential use in AD. Wheat straw reported the highest cellulose (37.8%) and hemicellulose (28.2%) content, and it was thus considered to be the most competitive feedstock for AD. Soybean straw had the lowest cellulose and hemicellulose content but it was found to have the highest lignin content (23.5%). The findings imply that soybean straw will have the lowest AD efficiency. © 2022 Society of Chemical Industry and John Wiley & Sons, Ltd.