Abstract

A newly-developed fine bubble aeration system, by which air is transferred under supercavitation conditions, shows a clearly better performance than traditional, well-known aerators that rely on the jet-pump principle (Schmid & Geier, 2003). The performance can be compared to oxygen transfer rates achieved in membrane and foil plate aerators. A prototype supercavitation aerator installed at a sewage treatment plant revealed an air input rate, which was about one third lower than that of the replaced jet pump system. In spite of this low air input rate, the daily demand of pure oxygen for the additionally installed membrane aeration system went down by approximately 49 percent, from the original level of about 1 200 m3/d to about 600 m3/d – and this over a test period of more than seven months. With this new aerator and during the first three months of test phase already, more than 10 000 Euros had been saved because of the reduced pure oxygen consumption. In this article, a review of the patents on different aspects of a new aeration technology using “supercavitation” is presented.

Keywords: Mechanical aeration, supercavitation, energy efficiency