Short tests to couple N2O emission mitigation and nitrogen removal strategies for landfill leachate recirculation

Landfills implemented with onsite leachate recirculation can efficiently remove pollutants, but currently they are reckoned as N2O emission hot spots. In this project, we evaluated the relationship between N2O emission and nitrogen (N) removal efficiency with different types of leachate recirculated. Nitrate supplemented leachate showed low N2O emission rates with the highest N removal efficiency (similar to 70%), which was equivalent to similar to 1% nitrogen emitted as N2O. Although in nitrite containing leachates' N removal efficiencies also reached to similar to 60%, their emitted N2O comprised similar to 40% of total removed nitrogen. Increasing nitrogen load promoted N2O emission and N removal efficiency, except in ammonia type leachate. When the ratio of BOO to total nitrogen increased from 0.2 to 0.4, the N2O emission flux from nitrate supplemented leachate decreased from similar to 25 to <0.5 mu g N/kg-soil . h. We argue prior to leachate in situ recirculation, sufficient pre-aeration is critical to mitigate N2O surges and simultaneously enhance nitrogen removal efficiency. (C) 2015 Elsevier B.V. All rights reserved.