Effect of Spent Air Reusing (SAR) on Maturity and Greenhouse Gas Emissions during Municipal Solid Waste (MSW) Composting-with Different Pile Height

As spent air holding high oxygen (O2) concentration (10%-20%) and heat energy from sealed composting reactor at high temperature period, it is feasible for waste degradation by aerobic microorganisms, and promotes composting pile's temperature rising in composting process based on reusing spent air. In this study, a new method of spent air reusing (SAR) was applied in composting to investigate the improvement of the compost maturity and greenhouse gas (GHG) emissions with different composting pile height. The four different trials were researched in this paper. The conventional composting trial (T0) with 2.5 m pile height composting was used as the control, and T1, T2, T3 with 2.5 m, 3.0 m, 3.5 m pile height composting were operated under SAR method. The results showed that the compost under SAR trials had better quality and less GHG emissions than T0. Meanwhile, the composting treatment capacity increased by 40% and total GHG emissions reduced by 25.70% CO2-equivalent per ton composting materials. This study suggested SAR as a new method not only could increase the capacity of MSW composting, but also reduce the GHG emissions.