Recent advances in mathematical modeling of nitrous oxides emissions from wastewater treatment processes.

Nitrous oxide (N 2 O) can be emitted from wastewater treatment contributing to its greenhouse gas footprint significantly. Mathematical modeling of N 2 O emissions is of great importance toward the understanding and reduction of the environmental impact of wastewater treatment systems. This article reviews the current status of the modeling of N 2 O emissions from wastewater treatment. The existing mathematical models describing all the known microbial pathways for N 2 O production are reviewed and discussed. These included N 2 O production by ammonia-oxidizing bacteria (AOB) through the hydroxylamine oxidation pathway and the AOB denitrification pathway, N 2 O production by heterotrophic denitrifiers through the denitrification pathway, and the integration of these pathways in single N 2 O models. The calibration and validation of these models using lab-scale and full-scale experimental data is also reviewed. We conclude that the mathematical modeling of N 2 O production, while is still being enhanced supported by new knowledge development, has reached a maturity that facilitates the estimation of site-specific N 2 O emissions and the development of mitigation strategies for a wastewater treatment plant taking into the specific design and operational conditions of the plant. [ABSTRACT FROM AUTHOR]