Abstract
In the course of diffuser performance measurement with the standard method under unsteady state used sodium sulfite, concentration change of oxygen in the aerated off gas can be observed by means of off gas method.
In early stage of the measurement oxygen concentration of off gas is gradually reduced and it arrives at minimum value while dissolved oxygen concentration in the liquid is suddenly brought down to zero.
The overall oxygen transfer coefficient KLa which is a typical parameter of diffuser performance can be derived from this minimum oxygen concentration. Experiment on diffuser performance measurement of the ceramic perforated plate has been conducted and the both values obtained from experimental results by off gas and sodium sulfite method under the same condition have been compared and they have agreed as a result of statistics test. This conclusion is very significant for diffuser performance measurement under operating condition because off gas method is actually only useful method for measurement of operating aeration tanks.
