Nitrous oxide emissions from aerated composting of organic waste

The composting of high organic content wastes has been shown to produce nit rous oxide (N2O). This study was initiated to investigate the mechanisms of N2O emissions from aerated composting and to determine the optimal operati onal conditions that minimize N2O emissions. The results of our experiment in laboratory-scale composters showed that more than 95% of N2O was produce d during the later period of composting when readily available carbon sourc es had been depleted. Significant increases in N2O emission after nitrite ( NO2-) addition, and good NO2- - N2O correlation, indicates that N2O was tra nsformed from NO2-. Extremely high N2O generation was observed after NO2- a ddition in the presence and absence of composted cattle manure. This sugges ts an identical mechanism for N2O production in both treatments. However, t he addition of composted cattle manure resulted in an earlier initiation of the main N2O generation period. Intermittent feeding of fresh food waste p ostponed the main N2O generation period, and reduced the mass-based N2O emi ssions by 20%.