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

Monitoring nitrous oxide (N2O) emissions fromwastewater 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 bywhichN2O is chemically stripped out fromwastewater and quantified by gas chromatography(GC-TCD) subsequently. Eight different inorganic salts have been evaluated for this purpose, likewise the applicationof ultrasound. By addition of sodium bromide (NaBr) the best recovery rate of about 98% (=1.14 ±0.05 kg·m−3) N2O from a saturated stock solution (1.16 kg·m−3, 295.85 K and 1 atm) was achieved. The application of ultrasound led to considerable smaller N2O recoveries of 37% (=0.43 ± 0.01 kg·m−3) after a 60 min 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 ± 0.20 g·m−3. Besides, N2O could be quantified in the activated sludge process with up to 9.87 ±0.50 g·m−3 yielding 7.75 g N2O·PE−1·a−1 specifically for the investigated wastewater treatment plant. Hence, the proposed method proved suitable as a routine quantification method for N2O

Kosse, P, Lübken, M., Schmidt, T. C., Wichern, M., 2017. Quantification of nitrous oxide in wastewater based on salt-induced stripping. Science of the Total Environment 601-602, pp. 83-88