ATAH Martins Chike

Department of Mechanical Engineering, Nnamdi Azikiwe University, Awka, Anambra State
Author    Correspondence author
Journal of Energy Bioscience, 2026, Vol. 17, No. 1   
Received: 07 Nov., 2025    Accepted: 29 Dec., 2025    Published: 06 Feb., 2026

This is an open access article published under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Rapid urbanization and waste generation have intensified the demand for sustainable energy and waste management solutions. This study investigates biomethane production through the co-digestion of household food waste (FW) and human excreta (HE), targeting renewable vehicle fuel applications. Laboratory-scale experiments were designed using the Taguchi method to optimize key parameters, including substrate mixing ratio, pH, retention time, and inoculum concentration. Results showed that co-digestion enhanced biomethane yield significantly, achieving 410 mL CH₄/g VS compared to 275 mL/g VS (FW alone) and 180 mL/g VS (HE alone). Process stability was improved by maintaining optimal volatile fatty acid to alkalinity ratios, reducing the risk of digester failure. Upgrading trials via membrane separation produced methane concentrations above 95%, meeting vehicle fuel standards. Techno-economic assessments indicated favorable cost-benefit performance, particularly when digestate utilization and carbon credits were included. Furthermore, pathogen inactivation protocols ensured safe digestate reuse, enhancing environmental and public health outcomes. Compared to existing literature, this study demonstrates superior methane yield and improved scalability prospects under real-world waste variability. The findings highlight the feasibility of integrating FW and HE co-digestion into urban renewable energy infrastructures, offering a sustainable pathway for circular economy and climate change mitigation.

Anaerobic co-digestion; Biomethane; Food waste; Human excreta; Process optimization; Renewable transport fuel; Circular economy