Design of Solid state digester for biogas production from banana wastes

Abstract

Processing of banana results in a huge amount of waste generation, leaves, stems and peels etc. Indiscriminate disposal of these wastes when decomposed produces noxious gases such as hydrogen sulphide and ammonia, which pose serious environmental hazards. Thus turning them into biomass feedstock offers a better waste management option and also source of energy production. For the past 30 years, there has been only biogas plants which are developed for treating cow dung as feed material. In those plants only other organic wastes are used as feed material. As banana wastes contain high moisture, they can be treated by the way of solid state digestion. The paper describes the design of solid state digester of 1 m3 capacity of biogas production, exclusively for treating banana wastes by the method of solid state anaerobic digestion. The reactor was designed based on the hydraulic retention time and the total solid content of the banana feedstock in order to complete digest and produce biogas at a faster rate with optimum quantity and methane content. The digester was designed for a feed capacity of 30 kg with 30 days retention time with a gas holder volume of 1 m3. The diameter and height of the digester are 1.09 m and 2.1 m and for gas holder the diameter and height are 1.01 m and 0.9 m respectively. The developed digester was found to convert 90% of the solid content in feed to bioenergy.