Hyperthermophilic Composting Significantly Decreases NO Emissions by Regulating NO-related Functional Genes

This study reported for the first time that hyperthermophilic composting (HTC) could mitigate 90% of the cumulative amount of NO emissions compared to traditional composting (TC) in a full-scale experiment. The concentrations of NO-N and NO-N in HTC were significantly lower than those in TC, which may be the main reason for the reduced NO emissions. Furthermore, this study found that the decrease in NO emissions in HTC compared to TC was mainly due to the inhibition of the abundance of the bacterial amoA and norB genes, which could decrease the nitrification rate and control NO formation, respectively. Partial least squares path modeling revealed that a high temperature was the key factor in lowering NO emissions in HTC, while physicochemical properties were the dominant factor in enhancing NO emissions in TC. These results suggested that HTC is a promising technique for reducing NO emissions in manure composting.