MASTER'S THESIS - SuSanA

5 Learning from already implemented CWs (in Albania and the Balkan region)
Figure 5.1 gives an overview over the special kinds of constructed wetlands.
Figure 5.1: Overview over CW types (Nowak n.y.,a)
Vertical filter beds (VF, see Figure 5.2) are fed between one and four times a day. The wastewater should be
applied equally on the surface. It is necessary to give enough time until the next feeding so that air can
penetrate the filter as well. Therefore, the filter area and the time between the feedings has to be
sufficient. VF show only low denitrification. They are normally divided into four parts and always one of the
four parts is out of use to recover. Most often VF beds are constructed as they require less space than HF
beds (Nowak 2010,a) and save therefore area and costs.
Figure 5.2: Vertical filter bed (Bodenfilter 2012)
Horizontal filter beds (HF, see Figure 5.3, p.53) are fed from the side and water flows horizontally through
the filter bed. They should permanently be banked up with water. HF show low nitrification but high
denitrification and therefore a high total nitrogen (TN) elimination. HF beds are constructed broader than
long in order to have short flow distances because of hydraulic reason and to guarantee at the same time a
long retention time to improve the biological process (Nowak 2010,a).
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