Valorization of Kitchen Waste from University Restaurants for Biogas Production - Case of Joseph KI-ZERBO University

Abstract

The management of food waste in university restaurants represents a significant environmental challenge, particularly in developing countries where waste treatment infrastructure is limited. This study investigates the energy valorization of kitchen waste generated by the central restaurant and its annexes (RU SIAO, RU Chinoise) at Joseph KI-ZERBO University in Ouagadougou, Burkina Faso, through anaerobic digestion. The objective is to propose a sustainable solution for managing food waste, reducing its environmental impact, and producing renewable energy. A quantitative and qualitative characterization of the waste was conducted over several weeks, assessing its volume, composition, and methanogenic potential. The results reveal an annual production of approximately 188.78 tons of waste, of which 72.2% consists of fermentable organic matter (rice, pasta, sauces, vegetables, peels), ideal for methanization. Laboratory tests, conducted with inoculum from the ONEA biogas plant in Kossodo, demonstrated a biogas yield of 320 to 350 L/kg of dry matter, with a methane content of 57 to 62%, suitable for local applications such as cooking, heating, or electricity production. The nutrient-rich digestate can be used as organic fertilizer for campus green spaces, reinforcing circular economy principles. Physicochemical analyses indicate a dry matter content of 22.4%, a volatile organic matter content of 86.5%, and an optimal C/N ratio of 25.3, promoting efficient anaerobic digestion under mesophilic conditions (35 ± 2°C). Challenges include seasonal variability in waste composition, the need for rigorous sorting to eliminate contaminants (plastics, packaging), and investment in infrastructure such as industrial digesters. To ensure success, the study recommends a strengthened selective sorting system, medium-scale pilot projects to validate technical and economic feasibility, and awareness-raising among students and staff. By adopting this strategy, Joseph KI-ZERBO University could reduce greenhouse gas emissions, minimize waste management costs, and become a model of sustainability for African academic institutions, contributing to sustainable development goals.