Biological Purification Systems of active sludge: "traditional outline"

The biological purification of active sludge “as traditionally outlined” is achieved in the version that is adopted today in the great city systems, which has passed the test of time, and is now achieving a favorable cost compromise between system costs and operating costs.

The biological purification of sewage waters happens in two stages:

1. following energy absorption, part of the polluting organic substances, at first, is oxidized, while at the same time new cellular substances are formed;
    

2. the bacteria easily concentrates in decantable ribbons (active sludge ribbons result and are therefore composed of a viscous substance, in which the bacteria and the protozoa are present while the carbonic acid, oxygen, and phosphorus are present approximately in the proportion of 5:1:0, 15).

The systems of active sludge are structured as follows:

• primary sedimentation is produced with Imhoff systems to which the digesters will be connected;
   

• Biological oxidation for the treatment of the primary sludge;
   

• Secondary sedimentation;
   

• Basin of accumulation and thickening of the stabilized sludge;
   

• Basin of chlorination.

The outline prescribed: a water line, whose treatments involve the purification of the liquid capacity of the sewage, and a sludge line, whose treatments involve the solid part separated from the liquid phase, that must also endure its specific treatments in order to be dried like solid waste.