Waste water treatment – Compressed air allows water to bubble


Waste water treatment is carried out by means of mechanical and biological clarification. In the case of mechanical clarification carried out beforehand, solid or slightly dissolved suspended components are removed from the sewage water. The biological clarification carried out afterwards uses microorganisms in the liquid to be clarified in order to remove the non-mechanically removed pollutants in the water to be clarified. Both side-blowers are used in both methods.

How it works:

The side channel compressor blows air into the clarifier. For this purpose, vents are attached to the basin floor which are connected to the side channel fan. The side channel fan presses air into the diffuser. As a result, small air bubbles emerge from the outlets and rise to the surface. Two objectives are achieved.


The air bubbles tear water particles by their emergence to the surface or upwards. As a result, water from the depth of the basin is continually swirled to the surface. In addition, surface water is displaced at the surface and conveyed into the depth. Since the surface of the water is absorbed by most of the oxygen in the air, oxygen-rich water is emitted into the depth and oxygen-deficient water can absorb oxygen on the surface.

Why is this necessary?

The micro-organisms need the biological clarification, therefore, for the decomposition of pollutants of the sewage water necessarily oxygen. The higher the oxygen content in the water, the faster and more effectively the microorganisms will decompose the pollutants. So we come to the second goal of the aeration of the clarification tank.


By inflowing air into the settling basin and distilling it into many small air bubbles, a large surface is created which represents a boundary between water and air similar to the water surface. At this limit, as in the water surface of the basin, oxygen dissolves in the water. The sewage water becomes more oxygen-rich. This measure also solves oxygen in the water, the oxygen content in the water increases, and the microorganisms can decompose the pollutants faster in the water.


As the reader recognizes on the principle sketch, the side channel compressor pushes its outflowing air into the outflow blocks. Technologically, the air is divided into many small vesicles, which flow upwards. The smaller the bubbles are, and the more the water is pressed into the water, the more oxygen is dissolved in the water per unit of time. The mechanical upward movement of the air bubbles leads to a circulation in the basin and a uniform distribution of the contents. The oxygen content of the clarification basin can now be measured and this information can be processed by a controller, which controls the side channel compressor.