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Kids&Science Water Waste Water and Water Pollution Purification Sewage Treatment Plants
Index
See also: Industrial Sewage, Natural Sewage, Household Sewage, Wastewater Treatment 

 

Sewage Treatment Plants

A sewage treatment plant consists of a mechanical step and a biological purification step.

First, the Mechanical Purification Step:

The wastewater that comes out of the sewer first passes through a grating, where all the big pieces are caught. Afterwards, it flows very slowly through the primary sedimentation basin. There, coarse dirt sinks to the ground and settles out.

Building instructions for a miniature sewage plant (mechanical purification) You need:

  • Dishwater
  • 4 plastic cups with a hole in the bottom



Fill each of the cups half full as shown in the sketch with:

  • Active charcoal (available at the drug store)

  • Fine sand
  • Gravel

Insert a coffee filter and place the cups into each other, the one with the filter on top. Place all of them into a glass jar.


Now carefully pour the dishwater into the topmost cup
and let it flow through

 

 

 

 

 

 

 

 

Collect the water in the glass. It looks clean. Is it really clean? Shake it! What do you observe?

 

 

In order to remove pollutants like detergents,

a biological purification step is necessary for complete purification.

In the activated sludge tank, the invisible dirt is in for it now. Certain bacteria decompose this kind of dirt. In order to work and breath, the bacteria need air. This air is blown into the basin from below.

After the purification in the treatment plant, the water is once again so clean, that it can be discharged into a river.

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