Enhancing composting efficiency and heavy metal stabilization through thermophilic microbial inoculation

Agricultural waste management is critical for reducing environmental pollution and enhancing soil health, particularly the treatment of organic waste containing heavy metals. This study investigates the distinct effects of mesophilic and thermophilic microbial inoculation on composting. Using rice straw and swine manure as feedstocks, composting piles were inoculated with mesophilic (<i>Bacillus subtilis</i> and <i>Trichoderma reesei</i>) or thermophilic (<i>Geobacillus stearothermophilus</i> and <i>Aspergillus fumigatus</i>) microorganisms, alongside a control group with no inoculation. The results revealed that thermophilic inoculation significantly enhanced organic degradation and humification, leading to more efficient stabilization of heavy metals such as Pb, Zn, and Cr, especially during the thermophilic and mature phases. Microbial community analysis showed that thermophilic inoculation created a more connected microbial network and boosted the microbial functionality. Spearman correlation analysis indicated that the enhanced key metabolic pathways of IT, particularly those involved in organic matter degradation and heavy metal detoxification, were associated with reduced metal bioavailability during thermophilic phase. These findings highlighting the potential of thermophilic inoculants for sustainable waste management and environmental protection.