Separation (waste water)

Under separation means the separation of activated sludge and purified wastewater in the secondary clarifier of a biological sewage treatment plant . The term sedimentation is incorrect or not always correct in this case, as there are two different regimes for settling the sludge:

Disperse separation

Separation in the association

Disperse separation

The disperse separation is characterized by the fact that the sludge flakes settle out individually. The process obeys the laws of sedimentation . A clear vertical concentration gradient forms. The supernatant, that is the area above the settling sludge, always contains a certain number of particles, so that the achievable transparency is only very low.

Separation in the association

When separated in a bandage, the sludge flakes form a three-dimensional network that acts as a depth filter . This also removes very fine particles from the supernatant during the settling process, so that very high levels of transparency can be achieved. A vertical concentration gradient does not develop, a sharp sludge level separates the settled sludge and the supernatant. Because of the high degree of purity of the supernatant produced, this state is the one that is desired in a sewage treatment plant .

The measurement of the separation regime can be done with the measuring device SCHLUMOSED .