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

Efficient recovery of nitrous oxide (NO) 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 integrated 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 contributing 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 concentrations and then used to explore the possibility of enhancing NO 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/m to 1.0 g-COD/g-N at the initial NO concentration of 420 g-N/m. Furthermore, sufficiently increasing the headspace volume of the reactor was considered an ideal strategy to obtain ideal NO production of 86.6 % under the studied conditions. The production of high-purity NO (98 %) confirmed the practical application potential of this integrated treatment technology to recover a valuable energy resource from NO-rich flue gas.