DUGi

Minimizing N2O emissions and carbon footprint on a full-scale activated sludge sequencing batch reactor

http://dugi.udg.edu/item/http:@@@@hdl.handle.net@@10256@@12605

A continuous, on-line quantification of the nitrous oxide (N2O) emissions from a full-scale sequencing batch reactor (SBR) placed in a municipal wastewater treatment plant (WWTP) was performed in this study. In general, N2O emissions from the biological wastewater treatment system were 97.1±6.9gN2O-N/Kg NH4+-N consumed or 6.8% of the influent NH4+-N load. In the WWTP of this study, N2O emissions accounted for over 60% of the total carbon footprint of the facility, on average. Different cycle configurations were implemented in the SBR aiming at reaching acceptable effluent values. Each cycle configuration consisted of sequences of aerated and non-aerated phases of different time length being controlled by the ammonium set-point fixed. Cycles with long aerated phases showed the largest N2O emissions, with the consequent increase in carbon footprint. Cycle configurations with intermittent aeration (aerated phases up to 20-30min followed by short anoxic phases) were proven to effectively reduce N2O emissions, without compromising nitrification performance or increasing electricity consumption. This is the first study in which a successful operational strategy for N2O mitigation is identified at full-scale.

This study was funded by the Spanish Government Ministerio de Economía y Competitividad (project CTM 2011-27163) and the European Commission FP7-PEOPLE-2011-CIG 303946 project. M. Pijuan acknowledges the Ramon y Cajal research fellowship (RYC-2009-04959) provided by the Spanish Government. Spanish and Portuguese Governments are acknowledged for Acciones Integradas (PRI-AIBPT-2011-1232) and Luso-Espanhola action E-61/12. R. Marques also acknowledges the European Commission for his travel grant through COST action ES1202 (Water 2020) and the Portuguese Fundaçao para a Ciencia e Tecnologia for his PhD grant (SFRH/BD/74515/2010)

Elsevier