International Science Community Association International Research Journal of Environmental Sciences 14 4 2025 10 22 From waste to energy and fertilizer: Optimizing laying hen manure valorization via anaerobic digestion and composting in Benin Republic, West Africa 20 32 EN Angel D. Deva 1 Department of Chemistry & Research Centre, Scott Christian College (Autonomous), Nagercoil-629003 (Affiliated to Manonmaniam Sundaranar University, Tirunelveli), Tamil Nadu, India Celin T. Sumitha 2 Department of Chemistry & Research Centre, Scott Christian College (Autonomous), Nagercoil-629003 (Affiliated to Manonmaniam Sundaranar University, Tirunelveli), Tamil Nadu, India Raj G. Allen Gnana 3 Department of Chemistry & Research Centre, Scott Christian College (Autonomous), Nagercoil-629003 (Affiliated to Manonmaniam Sundaranar University, Tirunelveli), Tamil Nadu, India V.S. Patil 1 Department of Microbiology, Lal Bahadur Shastri College of Arts, Science and Commerce, Satara-415002, Maharashtra, India S.V. Patil 2 Department of Botany, Lal Bahadur Shastri College of Arts, Science and Commerce, Satara-415002, Maharashtra, India Ao Samuel 1 Department of Physics, Kohima Science College, Kohima, Nagaland, India Thisa Vevosüh 2 Department of Physics, Kohima Science College, Kohima, Nagaland, India Kacchara Chetan 3 Department of Physics, Kohima Science College, Kohima, Nagaland, India Ahlonsou Egbemimon Daniel 1 Université Nationale des Sciences, Technologies, Ingénierie et Mathématiques, Benin and Laboratoire de Chimie Physique, Matériaux et Modélisations Moléculaires, Benin Sevalou Paterne Johanès Médessè 2 Faculté des Sciences Agronomiques, Université d'Abomey-Calavi, Benin Togbé F.C. Alexis 3 Université Nationale des Sciences, Technologies, Ingénierie et Mathématiques, Benin and Laboratoire de Chimie Physique, Matériaux et Modélisations Moléculaires, Benin Atchade Théodora 4 National Institute of Agricultural Research of Benin Kiki Claude 5 Institute of Urban Environment, Chinese Academy of Sciences, China Dalohoun Joachim K. 6 Institute of Urban Environment, Chinese Academy of Sciences, China Fatombi Jacques K. 7 Université Nationale des Sciences, Technologies, Ingénierie et Mathématiques, Benin Houndonougbo M. Frédéric 8 Faculté des Sciences Agronomiques, Université d'Abomey-Calavi, Benin > Research Paper 2025 8 3 2025 10 22 This research assesses the potential of composting and anaerobic digestion (AD) to convert laying hen manure into valuable resources in Benin Republic, offering solutions to pressing environmental and agronomic issues. Field surveys revealed that 85% of farms use litter systems, producing 38.5 tons/month of manure, primarily managed by direct spreading (95% of farmers), leading to plant burns and ammonia emissions. Physicochemical analysis showed litter manure (LM) had higher organic matter (OM: 16.2% vs. 5.7%) and potassium (1.22% vs. 0.61%) than battery manure (BM), but both exhibited low nitrogen (<1%) and imbalanced C/N ratios (5.4 - 15.8). Composting with sawdust improved C/N (17.5) and OM (37.9%), meeting fertilizer standards. AD of LM yielded 32.6m³ biogas/ton, significantly outperforming BM (3.4 m³/ton). Kinetic modeling identified the modified logistic model (R² = 0.993) and first-order kinetic model (R 2 = 0.999) as best describing biogas production, respectively for LM and BM, with LM showing biphasic degradation of complex organics. Temperature profiles confirmed efficient composting, with thermophilic phases (>55°C for 15 days) ensuring hygienization. The results underscore the promise of a dual-output system that generates renewable biogas alongside nutrient-rich compost. Optimal amendments included LM (C/N 15.8, OM 16.2%), composted BM (N 1.64%, OM 34.7%), and sawdust-amended LM compost (OM 37.9%, C/N 17.5). Digestates required further composting (N 0.07%, C/N 43.4). These findings advocate for replacing direct spreading with circular economy approaches, emphasizing scalable C/N adjustment and substrate optimization for West African contexts. Future research should pilot these methods with techno-economic analyses to facilitate adoption. Copyright@ International Science Community Association