Analysis of biological wastewater treatment processes using multicomponent gas phase mass balancing

A reactor system using off-gas analysis was developed for analyzing wastewater treatment process reactions. Using a mass spectrometer for the gas analysis provides the ability to simultaneously measure several gas components (such as oxygen, nitrogen, carbon dioxide, and argon). One of the benefits of the reactor design was the precise control of the dissolved oxygen concentration, uncoupled from the system turbulence, which was controlled via a gas recycle loop. This feature allowed control of the turbulence within the reactor without any need for mechanical stirring. Using oxygen as the test gas, the reactor was shown to perform well in the measurement of oxygen uptake rate of nitrifying activated sludge. The oxygen uptake rate calculations were made using a simple calibration method developed for the reactor system. The reactor was able to provide precise and accurate results for this test case. Furthermore, the system was capable of measuring under dynamic process conditions, as well as when the process rates were constant (steady state).