Borja Solís, a chemical engineer from UAB, has devoted his master thesis to N2O modelling. Nitrous oxide (N2O) is a greenhouse gas and an ozone layer depletion gas that can be produced and emitted during the biological nitrogen removal from wastewater treatment plants (WWTP). Lots of efforts are still have been doing for incorporate the nitrous oxide production through the different pathways (AOB and denitrifying organisms) and emission on mathematical models and couple those model with the existents ASMs. In this study, an updated ASM2d model, that accounts for the production of nitrous oxide from the recent developed models, has been used to study the associated emissions of a full scale WWTP. The hydraulic characterization was performed introducing a KBr pulse at the influent of the WWTP. The tracer samples were performed at different zones of the secondary treatment of the WWTP. It was observed that the flow is equally divided over the two lines of reactor and that each reactor works as an ideal continuous stirred tank reactor. The secondary settlers model flux obtained was similar to the Flux Piston Reactor. The WWTP was calibrated on steady state conditions and validated dynamically, modifying only the operational parameters and following the guidelines of a seeds methodology, based on the Fisher Information Matrix. The calibration and validation were successful only varying two parameters. A study of the N2O emissions factors was performed observing the major nitrous oxide emissions factor when nitrite was accumulated in the reactors. In addition, it was observed that the stripping efficiency is a prior candidate parameter to calibrate the futures N2O emission measures.
Luckily for GENOCOV, he will continue with us as a predoctoral researcher!