Design and operation of a single-stage plug-flow digester using organic wastes generated from University of Mauritius cafeteria

Abstract

Anaerobic digestion of solid wastes is considered as an attractive technique for the conversion of organic wastes into energy. There is a need to upgrade towards the development of biodigesters that would be applicable in Mauritian context for bio-energy production. In this paper, a 3-zone plug-flow anaerobic digestion system was designed for the food wastes generated at around 20 kg/day from the cafeteria at the University of Mauritius. A rectangular septic tank of dimensions length 2000 mm, width 1450 mm and height 1400 mm was chosen and modified to meet the requirement of the designed digester. The anaerobic digester was fed with cow dung to act as inoculums. Parameters such as temperature, pH and volatile fatty acids (VFA) were monitored to assess the performance of the digester. The digester was operated under mesophilic conditions to produce biogas. A high specific average daily yield of biogas of 50.25 L/kg of food wastes added was produced. An optimum pH was maintained with the cow dung acting as a good buffer.