Effect of air mixing on high-solids anaerobic digestion of cow manure: Performance and mechanism

This study aimed to further investigate the effect of air mixing on the performance of a high-solids anaerobic digestion system and reveal its underlying mechanisms via analyses of carbon conversion, microbial communities and key functional genes. When the air mixing intensity was 12.5, 37.5 and 62.5 mL/(L.min), compared with the anaerobic digestion without air mixing, the methane yield was increased by 6 %, 13 % and 6 %, respectively. The improved performance was partly attributed to the increased hydrolysis rate of macromolecular substances by 5 %-16 % and carbon recovery in the form of methane by 6 %-7% compared with the controls. Functional flora (Magnetospirillum, Synergistaceae) and hydrolytic metabolism-related enzymes (cellulose, alpha-amylase) demonstrated higher abundance under air mixing condition, thus promoting the degradation of organic matter and methane production. This work provides some new insights into the use of air mixing to improve anaerobic digestion of high-solids waste.

Automated summary

This study aimed to investigate the effect of air mixing on high-solids anaerobic digestion system performance and understand the mechanisms behind it. The results showed that the methane yield increased when different air mixing intensities were applied. The increase in performance was attributed to improved hydrolysis rate and carbon recovery, as well as the abundance of certain microorganisms and enzymes under air mixing condition.