Theoretical Frameworks for Understanding the Role of Indigenous Knowledge in Optimising Biogas Digester Performance in Rural North East Nigeria

The persistent underperformance of community biogas installations in rural North East Nigeria has been attributed to misalignment between engineered digester designs and the indigenous knowledge systems governing organic waste management and seasonal agricultural cycles in communities across Adamawa, Borno, and Yobe States. This study develops a theoretical framework integrating systems thinking, indigenous technical knowledge, and chemical engineering process optimisation principles to explain and predict the conditions under which indigenously managed biogas digesters achieve sustained high performance. The theoretical framework is grounded in Social-Technical Systems Theory adapted for low-resource settings, combined with a first-principles anaerobic digestion process model parameterised using substrate characterisation data for locally managed waste streams. Field data were collected from 24 community biogas installations in Adamawa and Yobe States through longitudinal process monitoring, semi-structured interviews with community operators, and ethnographic observation over 24 months. The framework identifies five determinant process variables, specifically substrate diversity, inoculation practice, seasonal loading adjustment, temperature management, and effluent use feedback, whose optimal management is encoded in indigenous knowledge that formal engineering design protocols typically ignore. Structural equation modelling confirmed that installations incorporating indigenous substrate management practices into operational protocols produced an average of 43% higher specific methane yield than those following conventional fixed-loading protocols. The study proposes an original knowledge co-production methodology for biogas technology development in rural Nigeria that bridges indigenous knowledge and process engineering theory. Keywords: biogas, indigenous knowledge, anaerobic digestion, North East Nigeria, systems thinking