Effect of iron-based nanomaterials on organic carbon dynamics and greenhouse gas emissions during composting process

Iron-based nanomaterials as effective additives can enhance the quality and safety of compost. However, their influence on organic carbon fractions changes and greenhouse gas emissions during composting remains unclear. This study demonstrated that iron-based nanomaterials facilitate the conversion of light organic carbon fraction into heavy organic carbon fraction, with the iron-based nanomaterials group showing a significantly higher heavy organic carbon fraction content (41.88%) compared to the control group (35.71%). This shift led to an increase in humic substance content (77.5 g/kg) and a reduction in greenhouse gas emissions, with CO₂, CH₄, and N₂O emissions decreasing by 20.5%, 39.7%, and 55.4%, respectively. Additionally, CO₂-equivalent emissions were reduced by 42.9%. Microbial analysis revealed that iron-based nanomaterials increased the abundance of Bacillus and reduced the abundance of methane-producing archaea such as Methanothermobacter and Methanomassiliicoccus. These results indicated that the role of iron-based nanomaterials in regulating reactive oxygen species production and specific microbial communities involved in humification process. This study provides a practical strategy for improving waste utilization efficiency and mitigating climate change.