Emission mitigation of CH4 and N2O during semi-permeable membrane covered hyperthermophilic aerobic composting of livestock manure

Membrane-covered composting and hyperthermophilic composting technologies have been proven to be effective and have been widely applied as organic waste recycling strategies. However, attempts to combine the two technologies have not been reported. Thus, this study constructed a novel semi-permeable membrane covered hyperthermophilic composting (smHTC) and investigated its potential in CH4 and N2O mitigation. Results showed that smHTC reduced the average emission flux of CH4 and N2O in the thermophilic phase of composting by 79% and 45%, compared to conventional thermophilic composting (cTC). The abiotic mechanism of CH4 and N2O emission mitigation could be attributed to the double barrier of semi-permeable membrane and sub-membrane water layer, which made it difficult for CH4 and N2O to escape, resulting in less CH4 and N2O being released into environment. As for the biotic mechanism, smHTC could suppress the abundance of mcrA gene and methanogens participated in methanogenic process through the high-temperature, which also contribute to the reduction of CH4 emissions. smHTC also could reduce the abundance of denitrification-related functional genes and related microbial taxa, this also facilitated the N2O mitigation. Overall, this work demonstrated the advantages of smHTC in greenhouse gas mitigation and could be a promising recycling strategy for organic waste.