<p>The air bubbles rising from the injecting pipes at the bottom of an activating tank for the biological treatment of sewage, pass, on their way to the surface through a mass of diverting elements which tend to hold them. The diverting elements fill the total volume of the tank and float freely in the water. Stubs of PVC piping are used as the diverting elements. These have a length of 30-60 mm and have a roughened corrugated surface. Used to increase the efficiency of activating tanks so that with the same amts. of space and energy costs, a higher degree of purificn. is achieved.</p>
