Real time monitoring of nitrous oxide emissions from wastewater treatment processes by membrane introduction mass spectrometry

Abstract

This project investigated membrane introduction mass spectrometry (MIMS) as a real time (on-line) analytical monitoring technique for nitrous oxide gas emissions from processes within a full-scale biological nutrient removal wastewater treatment plant. Experiments have shown that treatment processes including nitrification (aerobic - ammonia to nitrate) and denitrification (anoxic - nitrate to nitrogen gas) can become disrupted resulting in unintended nitrous oxide emissions (N2O). A limited number of studies have been conducted that monitor real time N2O emissions from full-scale treatment bioreactors and there remains significant uncertainty in true emissions. Two real time monitoring experiments (22 hours each) are shown where MIMS was able to track nitrous oxide emissions from the aerobic and anoxic zones of the bioreactor. Concentrations were calculated from response factors obtained using internal standard. Estimated quantities of nitrous oxide emissions under various scenarios and recommendations for future investigations are also provided.