Effect of Aeration Methods on the Organic Matter Degradation, Microbial Community and Their Catabolic Function During Composting

For the composting aeration, positive aeration (PA, blow type) is commonly used but suffers from the problem of odor diffusion, while negative aeration (NA, suction type) is scarcely used but it can minimize odor. However, the effect of aeration type on the organic matter degradation rate in large-scale composting is still unknown. In this study, we investigated the effect of aeration type on the organic matter degradation and the dynamics of the microbial community and catabolic function during composting using 200 L cylindrical drum reactors under self-heating condition. The organic matter degradation of Run PA was faster as compared to that of Run NA. This could be attributed to the higher heat retention in Run PA. The microbial community involved in the degradation of easily degradable material was found to be similar in both runs, despite different temperature profile and organic matter degradation rate. The key functional genes predicted by PICRUSt showed that the gene abundance of protease was similar in Run PA and Run NA, indicating that the high temperatures associated with Run PA accelerated the enzymatic activity but did not influence the microbial community nor their catabolic function. As a result of the increased organic matter degradation rate in PA, Thermobifida proliferated early and played a key role in degrading relatively hardly degradable material by hydrolysis of cellulose into cellobiose.