Fig. 3. Concentrations of (A) suspended solids (SS), (B) biochemical oxygen demand (BOD₅), and (C) chemical oxygen demand (COD) in the wastewater during 72 h of treatment in the planted channel with wooly digitalis (filled circles) and foxglove (open circles) and in the unplanted channel (filled triangles) in July 2000. The dashed line indicates the legal discharge level. Values are means ± standard deviations; n = 5.