Processing of East African Highland Green Bananas: Waste Generation and Characterization as a Potential Feedstock for Biogas Production in Uganda

Abstract

Uganda is the second largest global producer of bananas and the industry generates different waste residues both at production and processing levels. This study aimed at assessing the state of banana processing, waste generation and its characterization for evaluation as feedstock for biogas production. The study was undertaken through a reconnaissance visit to western Uganda, one of the most banana producing regions. The information was collected following standard qualitative methods and laboratory analysis. Results revealed that processing of banana fruits mainly involved manual peeling of fruits to generate fresh pulp and large quantities of banana waste. The waste contained more than 80 % moisture content and volatile solids. It also had higher carbon content than total nitrogen that translated into a high C:N ratio of 41:1. The lignocellulose content comprised cellulose 21.16 %, hemicelluloses 10.46 % and lignin 11.31 %. The Biochemical Methane Potential (BMP) test showed a methane yield of 0.436 m3 CH4/KgVS which was higher than 0.340 m3 CH4/KgVS for grass. The highest methane production of 79.9 ml CH4/gVS/day was recorded at a retention time of 24 days. These results showed that banana waste was a favorable feedstock for biogas production through anaerobic digestion. Appropriate pre-treatment of lignocellulose would be required to enhance feedstock digestibility to improve biogas yield. The study concluded that utilization of banana waste via anaerobic digestion to produce biogas was the most economically viable option to alleviate the industry’s energy scarcity