Generalities
26
Figure 12: Bacterial beds (Bouchentouf &Abdarrahmane, 2021).
• Biological disks
This aerobic biological process consists in feeding wastewater that has been previously
decanted or screened into a structure in which disks fixed on a horizontal axis are rotated at
slow speed. These disks support the development of purifying microorganisms (biofilm), which
draw the oxygen they need from the water to be treated, absorbing the dissolved pollution on
which they feed. When the biofilm exceeds a thickness of a few millimeters, it detaches and
heads towards a clarifier, where it separates from the purified water. (Boutin et al., 2016).