title: Calibration and validation of an activated sludge model for greenhouse gases no. 1 (ASMG1): prediction of temperature-dependent N₂O emission dynamics.
abstract: An activated sludge model for greenhouse gases no. 1 was calibrated with data from a wastewater treatment plant (WWTP) without control systems and validated with data from three similar plants equipped with control systems. Special about the calibration/validation approach adopted in this paper is that the data are obtained from simulations with a mathematical model that is widely accepted to describe effluent quality and operating costs of actual WWTPs, the Benchmark Simulation Model No. 2 (BSM2). The calibration also aimed at fitting the model to typical observed nitrous oxide (N₂O) emission data, i.e., a yearly average of 0.5% of the influent total nitrogen load emitted as N₂O-N. Model validation was performed by challenging the model in configurations with different control strategies. The kinetic term describing the dissolved oxygen effect on the denitrification by ammonia-oxidizing bacteria (AOB) was modified into a Haldane term. Both original and Haldane-modified models passed calibration and validation. Even though their yearly averaged values were similar, the two models presented different dynamic N₂O emissions under cold temperature conditions and control. Therefore, data collected in such situations can potentially permit model discrimination. Observed seasonal trends in N₂O emissions are simulated well with both original and Haldane-modified models. A mechanistic explanation based on the temperature-dependent interaction between heterotrophic and autotrophic N₂O pathways was provided. Finally, while adding the AOB denitrification pathway to a model with only heterotrophic N₂O production showed little impact on effluent quality and operating cost criteria, it clearly affected N2O emission productions.
authors.affiliation: modelEAU, Département de génie civil et de génie des eaux, Université Laval, 1065 Av. de la Médecine, Quebec, QC, G1V 0A6, Canada, lisha.guo.1@ulaval.ca.
authors.forename: Lisha
authors.initials: L
authors.lastname: Guo
authors.forename: Peter A
authors.initials: PA
authors.lastname: Vanrolleghem
mesh_terms: D002138:Calibration; D005740:Gases / Q000737:chemistry*; D017752:Greenhouse Effect; D007700:Kinetics; D008962:Models, Theoretical; D009609:Nitrous Oxide / Q000032:analysis*; D012722:Sewage; D013696:Temperature
chemical_list: D005740:Gases; D012722:Sewage; D009609:Nitrous Oxide