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Chemosphere. 2016 Sep;158:9-16. doi: 10.1016/j.chemosphere.2016.05.046. Epub 2016 May 26.

A fundamental study on biological removal of N2O in the presence of oxygen.

Author information

1
Department of Chemical Engineering and Environmental Technology, University of Valladolid, Dr. Mergelina, s/n, 47011 Valladolid, Spain; Agrarian Engineering School, University of Valladolid - Soria Campus, C/Universidad s/n, 42004, Soria, Spain. Electronic address: figueroa@iq.uva.es.
2
Department of Chemical Engineering and Environmental Technology, University of Valladolid, Dr. Mergelina, s/n, 47011 Valladolid, Spain; Agrarian Engineering School, University of Valladolid - Soria Campus, C/Universidad s/n, 42004, Soria, Spain.
3
Department of Chemical Engineering and Environmental Technology, University of Valladolid, Dr. Mergelina, s/n, 47011 Valladolid, Spain.

Abstract

The biodegradation of N2O by a non-acclimated secondary activated sludge in the presence of O2 was studied. Batch tests with a headspace containing an initial N2O concentration of ∼400 mg m(-3) (∼200 ppmv) and initial O2 gas concentrations of 0%, 1%, 2%, 5% and 21% were investigated. The effect of O2 on the biokinetic parameters qmax (maximum specific N2O uptake rate) and KS (half-saturation constant), as well as on the bacterial population structure, was evaluated. A complete N2O removal was recorded in the presence of up to 2% O2, while O2 at 5% and 21% mediated inhibitions of 37% and 95% in the removal of N2O compared with the control without O2. The elemental analysis of the biomass obtained at the end of the batch tests strongly suggested that NN2O was not used as a nitrogen source. The presence of O2 mediated decreases of up to 12.6- and 4.8-fold in qmax and KS, respectively, compared to the control without O2. Likewise, the presence of O2 induced changes in the structure of the bacterial population. The predominant microorganisms in the presence of O2 belonged to the phyla Proteobacteria, Firmicutes and Chlamydiae. Bacteria belonging to the Proteobacteria phylum, particularly the Dokdonella genus, were predominant at 2% O2, which was the highest O2 concentration without inhibitory effects on N2O biodegradation.

KEYWORDS:

Biokinetic parameters; Microbial communities; N(2)O removal; Oxygen influence

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