6. Horizontal flow planted filters

6.1 Primary treatment: principle

This system must be preceded by primary treatment (settling tank, settling lagoon, vertical flow planted filter, etc.).

In filtration systems designed for horizontal flow (Figures 13 and 14 ), the filter bed is almost completely immersed in the water. The effluent to be treated is distributed evenly over the entire surface and depth of the filter bed by means of an effluent distribution device located at one end of the filtration basin.