Biological Nitrous Oxide Abatement by Paracoccus denitrificans in Bubble Column and Airlift Reactors
Frutos, O.D.
Cortes, I.
Arnaiz, E.
Lebrero, R.
Munoz, R.
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Frutos O., Cortes I., Arnaiz E., Lebrero R., Munoz R., 2016, Biological Nitrous Oxide Abatement by Paracoccus denitrificans in Bubble Column and Airlift Reactors, Chemical Engineering Transactions, 54, 289-294.
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Nitrous oxide (N2O), with a global warming potential 300 times higher than that of CO2, represents 6.2 % of the total greenhouse gas emission inventory worldwide. Furthermore, N2O is considered the most critical O3- depleting substance emitted in this XXI century. In spite of the environmental relevance of this pollutant, very little research on biotechnologies for the treatment of N2O emissions has been conducted. In this study, the potential of a bubble column (BCR) and an internal loop airlift (ALR) bioreactors of 2.3 L was evaluated for the abatement of N2O from industrial emissions from nitric acid plants along 62 days of operation. The systems were inoculated with a methylotrophic Paracoccus denitrificans strain (DSM 413) and continuously supplied with methanol as a carbon and electron donor source for the anoxic reduction of N2O. The simulated waste gas consisted of a N2 gas stream containing 1 ± 0.1 % of O2 and 3377 ± 312 ppmv of N2O at the inlet of theBCR and 1 ± 0.1 % of O2 with N2O concentration of 3617 ± 342 ppmv at the inlet of the ALR. This N2-laden stream was supplied at a constant flow rate of 110 ml min-1 in each reactor. The performance of the BCR was characterized by a steady state N2O removal efficiency (RE) of 87 ± 3 % with CO2 productions of 308 ± 36 gm-3 d-1 and total suspended solid (TSS) concentrations of 867 ± 109 mg L-1. On the other hand, the ALR showed a N2O RE of 88 ± 2 % with productions of CO2 of 346 ± 28 g m-3 d-1 and TSS concentrations of 874 ±88 mg L-1. This work constitutes, to the best of our knowledge, the first systematic study of a biotechnology for the continuous abatement of N2O from nitric acid plants.
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