Spatial Modeling and Review of Human Fecal Waste Re-Use in Rural Oromia, Ethiopia: Biomethane and Nutrient Recovery Potential

Ethiopia’s reduction in open defecation contrasts with persistent sanitation challenges, as most rural latrines remain unimproved, risking pollution and public health. This study quantifies biomethane and nutrient recovery potential from human feces in Oromia using high-resolution population (GHS-POP R2023A) and settlement data (GHS-SMOD R2023A) integrated with experimental findings. Annual per capita feces production is 73 kg, yielding 28.71 m³ methane and nutrients of 3.71 g N, 1.12 g P, and 2.29 g K per kg. Rural Oromia produces ~ 2 million tonnes of feces yearly, with an energy potential of 27.89 PJ (775 million m³ methane) and recoverable nutrients valued at over 2.6 billion birr in synthetic fertilizer equivalents. Spatial hotspots in central and southwestern districts highlight priority areas for intervention. Resource-Oriented Toilet Systems offer sustainable sanitation, renewable energy, and agricultural benefits but face cultural, economic, and institutional barriers. The study underscores the need for integrated policies and culturally sensitive approaches to advance Ethiopia’s circular sanitation economy.