Fig. 4. Concentration of (A) suspended solids (SS), (B) biochemical oxygen demand (BOD₅), (C) chemical oxygen demand (COD), (D) total P, and (E) total nitrogen in the wastewater before the treatment and after 48 h of treatment in the planted channel with wooly digitalis and foxglove and in the unplanted channel (June–December 2000). The dashed lines indicate the legal discharge level and the dotted lines indicate the legal discharge level in eutrophically sensitive areas. Arrows represent wooly digitalis death. Values are means ± standard deviations; n = 5.