N 2O and NH 3 emissions from a bioreactor landfill operated under limited aerobic degradation conditions

Abstract

The combination of leachate recirculation and aeration to landfill may be an efficient way for in-situ nitrogen removal. However, nitrogenous substances contained in the landfill layer are concomitantly transformed into N 2O and NH 3, leading to increased emissions into the atmosphere. In the present study, the emissions of N 2O and NH 3 were measured under conditions of fresh or partially stabilized refuse with or without leachate recirculation or intermittent aeration. The results showed that the largest N 2O emission (12.4 mg-N/L of the column) was observed in the aerated column loaded with partially stabilized refuse and recycled with the leachate of low C/N ratio; while less than 0.33 mg-N/L of the column was produced in the other columns. N 2O production was positively correlated with the prolonged aerobic time and negatively related with the C/N ratio in the recycled leachate. NH 3 volatilization increased with enhanced gas flow and concentration of free ammonia in the leachate, and the highest cumulative volatilization quantity was 1.7 mg-N/L of the column.