Quantification of nitrous oxide in wastewater based on salt-induced stripping

Pascal Kosse; Manfred Lübken; Torsten C Schmidt; Marc Wichern

doi:10.1016/j.scitotenv.2017.05.053

Quantification of nitrous oxide in wastewater based on salt-induced stripping

Sci Total Environ. 2017 Dec 1:601-602:83-88. doi: 10.1016/j.scitotenv.2017.05.053. Epub 2017 May 24.

Authors

Pascal Kosse¹, Manfred Lübken², Torsten C Schmidt³, Marc Wichern²

Affiliations

¹ Institute of Urban Water Management and Environmental Engineering, Ruhr-Universität Bochum, Universitätsstraße 150, 44780 Bochum, Germany. Electronic address: pascal.kosse@rub.de.
² Institute of Urban Water Management and Environmental Engineering, Ruhr-Universität Bochum, Universitätsstraße 150, 44780 Bochum, Germany.
³ Instrumental Analytical Chemistry, University of Duisburg-Essen, Universitätsstraße 5, 45141 Essen, Germany; Centre for Water and Environmental Research (ZWU), University of Duisburg-Essen, Universitätsstraße 2, 45141 Essen, Germany.

PMID: 28550728
DOI: 10.1016/j.scitotenv.2017.05.053

Abstract

Monitoring nitrous oxide (N₂O) emissions from wastewater treatment plants has attracted much attention in recent years demanding accurate and rapid quantification methods. In the present study a salt-assisted methodology is proposed by which N₂O is chemically stripped out from wastewater and quantified by gas chromatography (GC-TCD) subsequently. Eight different inorganic salts have been evaluated for this purpose, likewise the application of ultrasound. By addition of sodium bromide (NaBr) the best recovery rate of about 98% (=1.14±0.05kg·m^-3) N₂O from a saturated stock solution (1.16kg·m^-3, 295.85K and 1atm) was achieved. The application of ultrasound led to considerable smaller N₂O recoveries of 37% (=0.43±0.01kg·m^-3) after a 60min treatment. Practical applicability of the method has been demonstrated by applying NaBr to grab samples from a municipal wastewater treatment plant. The highest N₂O concentration was found in the secondary clarifier with 10.99±0.20g·m^-3. Besides, N₂O could be quantified in the activated sludge process with up to 9.87±0.50g·m^-3 yielding 7.75gN₂O·PE^-1·a^-1 specifically for the investigated wastewater treatment plant. Hence, the proposed method proved suitable as a routine quantification method for N₂O.

Keywords: Greenhouse gases; Nitrous oxide; Salt-induced stripping; Sodium bromide; Ultrasound.