Efficient Conversion of Livestock Manure via Bioconversion Model

Research conducted at Hunan Agricultural University has led to the development of a new bioconversion model for livestock manure, utilizing the black soldier fly (BSF) as a resource. However, the biochemical properties of BSF manure are unstable, posing potential risks to crops. To mitigate this, additives such as biochar, humic acid, and tea residue were investigated for their ability to remove heavy metals and pathogens from BSF compost. The study found that humic acid and biochar were particularly effective in inhibiting the growth of pathogens, with biochar showing a significant reduction in the availability of zinc (58.9%) and arsenic (51.7%). The research also highlighted the importance of organic matter, electrical conductivity, and temperature in affecting the presence of pathogenic bacteria.

Key Takeaways:

• The bioconversion of black soldier fly (BSF) manure is a new model of livestock manure resourcing, but the biochemical properties of BSF manure are unstable and can be harmful to crops.
• Biochar, humic acid, and tea residue were investigated as additives to remove heavy metals and pathogens from BSF compost, with humic acid and biochar showing significant effectiveness.
• Biochar inhibited the availability of zinc (58.9%) and arsenic (51.7%), while humic acid and tea residue reduced the availability of zinc (60.8%) and arsenic (42.5%) respectively.
• Humic acid and biochar were found to be more helpful in inhibiting the growth of pathogens, with significant reductions in pathogenic bacteria (80.1-96.0%) and pathogenic fungi (41.4-99.9%).
• The abundance of dominant pathogenic genera was reduced by additive modulation, with OM, EC, and temperature being the most key factors affecting the presence of pathogenic bacteria. OM, pH, EC, Cu, Zn, and Cr also responded significantly to the presence of pathogenic fungi.
• Yong He, College of Environment and Ecology, Hunan Agricultural University, Changsha, Hunan 410028, People's Republic of China led the research team, which included Nanyi Wang, Xiaobing Zhang, Ying Wang, Hua Peng, Jiachao Zhang, Xichen Zhao, Anwei Chen, Renli Qi, Dan Wan, Lin Luo, and Liuqin He.
• The study provides theoretical guidance for the removal of pollutants in compost, promoting the efficient conversion of livestock manure via BSF.

Statistics:

• 58.9% reduction in the availability of zinc with the use of biochar
• 51.7% reduction in the availability of arsenic with the use of biochar
• 60.8% reduction in the availability of zinc with the use of humic acid
• 42.5% reduction in the availability of arsenic with the use of tea residue
• 80.1-96.0% reduction in pathogenic bacteria with the use of humic acid and biochar
• 41.4-99.9% reduction in pathogenic fungi with the use of humic acid and biochar
• Significant reductions in the abundance of dominant pathogenic genera with the use of additives
• OM, EC, and temperature were the most key factors affecting the presence of pathogenic bacteria, with OM, pH, EC, Cu, Zn, and Cr also responding significantly to the presence of pathogenic fungi.

Sources:

• Assessment of the combined response of heavy metals and human pathogens to different additives during composting of black soldier fly manure. Journal of Hazardous Materials, 2025;493:138347.
• Journal of Hazardous Materials. Elsevier, Radarweg 29, 1043 Nx Amsterdam, Netherlands. (Elsevier - www.elsevier.com; Journal of Hazardous Materials - www.journals.elsevier.com/journal-of-hazardous-materials/)
• Yong He, College of Environment and Ecology, Hunan Agricultural University, Changsha, Hunan 410028, People's Republic of China.
• Nanyi Wang, Xiaobing Zhang, Ying Wang, Hua Peng, Jiachao Zhang, Xichen Zhao, Anwei Chen, Renli Qi, Dan Wan, Lin Luo, and Liuqin He.