A new strategy to increase compost carbon fixation: Shell powder reduced gaseous pollutant emissions in co-composting of cow manure and sawdust

Abstract

To reduce gas emission and convert inorganic carbon into humus more efficiently has become a key research direction in composting. Microorganisms were the main factor affecting gas emissions. Because of its rich nutrients and porous structure, shell powder (SP) can change the succession of microorganisms during composting. The result showed that SP was found to reduce the emissions of CH4 (CK: 4.99 g; T: 3.21 g) and CO2 (CK: 114.48 g; T: 79.23 g) during composting, especially in the thermophilic phase. SP increased the DOM (CK: 20.91 mg/g; T: 26.92 mg/g) and HS (CK: 19.32 g/kg; T: 21.17 g/kg) content of the final compost product. SP increased the abundance of cbbL and Actinobacteria, and decreased mcrA abundance. cbbL and mcrA were identified as key genes for CO2 and CH4 metabolism, respectively. And Actinobacteria was identified as a key microorganism for carbon fixation and conversion during composting. This study can provide a new strategy for improving composting performances and compost quality.