Upgrading Oxygen Transfer in the Activated Sludge Process

Abstract

The objectives were to get some information on the variation of the alpha factor and to study factors affecting oxygen transfer efficiency in fine-bubble aeration. Results from a 5 week continuous operation of a batch aeration column process show that the variation of the alpha factor was considerable in the aeration basin, especially at the inlet end. The variation follows a diurnal rhythm and the weekly variation is much smaller. The off-gas method was used to examine factors affecting oxygen transfer in process conditions. Regression models were constructed to describe the transfer process both on a semitechnical scale and on a full scale. The most important factors are the specific air flow rate, the respiration rate and the DO concentration. The enhancement in OTE through the respiration rate and the DO concentration is due to a biological mechanism. To optimize the transfer process it is necessary to maintain a high respiration rate and a sufficiently high DO concentration.