Enhancing nitrogen conversion and microbial dynamics in swine manure composting process through inoculation with a microbial consortium

Microbial inoculation plays a crucial role in enhancing the efficiency of biowaste conversion. In this study, we investigated the effects of inoculating a complex microbial agent called the BP consortium, comprising Bacillus licheniformis, Bacillus subtilis, and Penicillium chrysogenum, at different stages of swine manure (SM) aerobic composting, specifically the initial stage and cooling stage. Our objective was to examine the impact of BP inoculation on nitrogen conversion, enzyme activity, and microbial community dynamics through a 35-day aerobic composting experiment. Compared to the group without the inoculant, initial-stage inoculation of BP led to a remarkable increase of 23.12% and 140.91% in the germination index and NO3- -N content of the final product, respectively. Furthermore, it effectively reduced NH3 and N2O releases by 65.73% and 18.76% during the SM composting process. The activities of urease also exhibited significant increase at the conclusion of the experiment. Additionally, we observed a proportional increase in the number of Proteobacteria and Actinobacteria during the thermophilic stage of composting. However, BP inoculation during the cooling phase did not demonstrate a positive effect on nitrogen retention. Nevertheless, the findings from this investigation provide valuable guidance for the implementation of BP consortium inoculation to mitigate nitrogen loss during SM aerobic composting.