Modelling Ninf2/infO production and emissions

Abstract

Mathematical modelling of Ninf2/infO emissions is of great importance for the understanding and reduction of the environmental impact of wastewater treatment systems. This chapter reviews the current status of the modelling of Ninf2/infO emissions from wastewater treatment. The existing mathematical models describing all known microbial pathways for Ninf2/infO production are reviewed and discussed. These include Ninf2/infO production and consumption by heterotrophic denitrifiers, Ninf2/infO production by ammonia-oxidizing bacteria (AOB) through the hydroxylamine oxidation pathway and the AOB denitrification pathway and the integration of these pathways in single-pathway Ninf2/infO models. The two-pathway models are compared to single-pathway models. The calibration and validation of these models using lab-scale and full-scale experimental data is also reviewed. The mathematical modelling of Ninf2/infO production, while still being enhanced by new knowledge development, has reached a maturity that facilitates the estimation of site-specific Ninf2/infO emissions and the development of mitigation strategies for wastewater treatment plants taking into account the specific design and operational conditions of the plant.