Micro-positive pressure significantly decreases greenhouse gas emissions by regulating archaeal community during industrial-scale dairy manure composting.

ABSTRACT

In this study, the effects of micro-positive pressure formed by covering with a semipermeable membrane in the heating phase of dairy manure composting on greenhouse gas emissions and the mechanism of reducing methane emissions by the archaeal community were investigated. A large-scale experiment was conducted with semipermeable membrane-covered composting (SMC), forced aeration composting (FAC), and traditional static composting (TSC) groups. The results showed that the oxygen concentration and methanogen abundance were key factors in regulating methane emissions. In the heating phase of SMC, the micro-positive pressure could enhance the O2 utilization rate and heating rate, resulting in Methanobrevibacter and Methanobacterium greatly decreasing, and the abundance of mcrA decreased by 90.03%, while that of pmoA did not increase. Compared with FAC and TSC, the cumulative methane emissions in SMC decreased by 51.75% and 96.04%, respectively. Therefore, the micro-positive pressure could effectively reduce greenhouse gas emissions by inhibiting the growth of methanogens.