Advancing renewable bioenergy from livestock waste through microparticle-assisted anaerobic digestion

The global transition toward renewable energy requires efficient and locally sourced solutions to replace fossil fuels while reducing greenhouse gas emissions. Biogas production through anaerobic digestion (AD) represents a sustainable technology that simultaneously manages organic waste and generates renewable energy. However, its performance often remains limited by low conversion efficiency and process instability, particularly when treating high-load organic substrates such as livestock manure. This study investigates the use of catalytic microparticles as an emerging and promising strategy to enhance AD performance and energy yield. Batch experiments were conducted over 50 days using iron (II,III) oxide (Fe 3 O 4 ), biochar, graphite, and Bio-Fe additives at two concentrations (5 and 15 mg/g VS), compared to a control without additives. Biogas production kinetics were evaluated using the modified Gompertz model, which provided excellent fits (R² > 0.96) and negligible lag phases. The control achieved a cumulative biogas yield of 431.8 mL/g VS, while Biochar L2 reached 667.4 mL/g VS, maintaining stable production throughout. Bio-Fe showed the highest biogas production rate (R m = 38.3 mL biogas·g −1 VS·day −1 ), while Fe 3 O 4 maintained consistent productivity over time. Furthermore, iron-based additives reduced hydrogen sulfide (H 2 S) levels by up to 39%, significantly improving biogas quality. These findings demonstrate that microparticle-assisted AD enhances both biogas yield and purity, offering a promising route for efficient renewable energy recovery from livestock waste.