Concurrent measurement of nitrous oxide and oxygen transfer in full-scale activated sludge basins

To gain insight on nitrous oxide (N2O) stripping so as to better model greenhouse gas emissions from wastewater treatment plants, a novel method for simultaneous measurement of N2O and oxygen (O2) transfer was developed and tested in a full-scale activated sludge basin. FTIR and O2 analyzers were used concurrently alongside dissolved gas probes to measure transfer of O2 and N2O. This method of simultaneous measurements performed well, with some limitations due to activated sludge basin turbulence, and demonstrated great potential for use in future experiments. Dissolved N2O measurements from this method were used to model emitted N2O, and the resulting model accurately represented temporal variations in emissions. An empirically determined correction factor was necessary to match the magnitude of measured and modeled emissions, and additional research is needed to understand the water quality conditions that impact this correction factor.