Towards efficient heterotrophic recovery of N2O via Fe(II)EDTA-NO: A modeling study

Efficient recovery of nitrous oxide (N2O) through heterotrophic denitrification with the help of Fe(II)EDTA-NO as a chelating agent has been regarded as an ideal technology to treat nitric oxide (NO)-rich flue gas. In this study, an in-tegrated NO-based biological denitrification model was developed to describe the sequential reduction of the NO fixed in Fe(II)EDTA-NO with organic carbon as the electron donor. With the inclusion of only the key pathways con-tributing to nitrogen transformation, the model was firstly developed and then calibrated/validated and evaluated using the data of batch tests mediated by the identified functional heterotrophic bacteria at various substrates concen-trations and then used to explore the possibility of enhancing N2O recovery by altering the substrates condition and reactor setup. The results demonstrated that the optimal COD/N ratio decreased consistently from 1.5 g-COD/g-N at the initial NO concentration of 40 g-N/m3 to 1.0 g-COD/g-N at the initial NO concentration of 420 g-N/m3. Further-more, sufficiently increasing the headspace volume of the reactor was considered an ideal strategy to obtain ideal N2O production of 86.6 % under the studied conditions. The production of high-purity N2O (98 %) confirmed the prac-tical application potential of this integrated treatment technology to recover a valuable energy resource from NO-rich flue gas.