The different operations of purification of a residual water generate a series of residues that can qualify in two groups:
- Solid thick: that normally are obtained in the pretreatments and that, in general, or are incinerated or are spilt in dumps.
- Muds: that are generated both in primary treatments and in the secondary ones.
The muds or mires appear in liquid or semisolid form and with a content of between 0,25 and 12% (in weight) of solid, according to the process of which they precede. The muds will surrender to one or another treatment as its origin and its pollutant or toxic load. These treatments try to reduce the volume of these mires.
Centrifugation. It allows to separate solid of liquids.
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Stabilization: The mires can be stabilized by means of aerobic or anaerobic digestion.
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Dehydration of mires: to diminish the content of dampness of the mires they use:
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Dried areas. It consists of the disposition of the mires to dry on a surface outdoors endowed with a good drainage.
4. Filtration. There are used filters of emptiness and press filters for the dehydration of mires.
Finally, the mires can be incinerated, applied to composting or direct application to soil, withdrawn from dumps controlled or personnel to stabilize or to refill areas.
