Vertical-horizontal filter unit for the biological purification of polluted water

A vertical-horizontal filter unit for the biological purification of polluted water, comprising:

• an upper filter zone (3), comprising gravel, sand, or the like, having feeds (1) for the polluted water,
• a lower filter zone (5), situated beneath it, comprising gravel, sand, or the like, optionally a barrier layer (4) having opening(s) between upper and lower filter zones (3, 5),
• and at least one removal location (7), the polluted water permeating the lower filter zone (5) after permeating the upper filter zone (3) and the filter unit having a seal (8) in relation to the soil on its sides and/or its floor,
• characterized by the following features:
• a medium, which contains organic carbon, may be introduced into the lower filter zone (5) via a device (6),
• the upper filter zone (3) is an aerobic filter zone, in which a nitrification of the polluted water occurs,
• the lower filter zone (5) is an anaerobic filter zone, having denitrifying microorganisms, in which mixing and denitrification of the nitrified polluted water, which was treated in the upper filter zone (3), with a medium, which contains organic carbon, occurs,
• the lower filter zone (3) and the upper filter zone (5) are implemented homogeneously.