Intermittent aeration mitigating carbon emission from landfills with gas-water joint regulation.

Landfill is a significant source of atmospheric CH and CO emissions. In this study, four landfill reactor systems were constructed to investigate the effects of different ventilation methods, including continuous aeration (20 h d) and intermittent aeration (continuous aeration for 4 h d and 2 h of aeration every 12 h, twice a day), on properties of landfilled waste and emissions of CH and CO, in comparison to a traditional landfill. Compared with continuous aeration, intermittent aeration could reduce the potential global warming effect of the CH and CO emissions, especially multiple intermittent aeration. The CH and CO emissions could be predicted by the multiple linear regression model based on the contents of carbon, sulfur and/or pH during landfill stabilization. Both intermittent and continuous aeration could enhance the methane oxidation activity of landfilled waste. The aerobic methane oxidation activity of landfilled waste reached the maximums of 50.77-73.78 μg g h after aeration for 5 or 15 d, which was higher than the anaerobic methane oxidation activity (0.45-1.27 μg g h). CO was the predominant form of organic carbon loss in the bioreactor landfills. Candidatus Methylomirabilis, Methylobacter, Methylomonas and Crenothrix were the main methane-oxidating microorganisms (MOM) in the landfills. Total, NO-N, pH and Fe were the main environmental variables influencing the MOM community, among which NO-N and pH had the significant impact on the MOM community. Partial least squares path modelling indicated that aeration modes mainly influenced the emissions of CH and CO by affecting the degradation of landfilled waste, environmental variables and microbial activities. The results would be helpful for designing aeration systems to reduce the emissions of CH and CO, and the cost during landfill stabilization.