Fig. 7

RDA for biotests with water samples taken at different cleaning stages at the WWTP Langwiese. Tests conducted with effluent samples after primary treatment were excluded. Left: first (horizontal) and second (vertical) axes; right: second (horizontal) and third (vertical) axes. The results for the “old” effluent with sand filter only (without activated carbon) are represented by green dots, the results for analyses with water samples taken after the secondary clarifier are shown in red, and analyses with samples taken after treatment with activated carbon plus sand filtration (“new” effluent) are shown in black and pink (black: only activated carbon; pink both activated carbon plus sand filter). Red arrows depict the investigated endpoints. The length of the arrow indicates the magnitude of effect, and the distance between the arrow and axes indicates their strength of correlation. Y(A)ES: Yeast (anti-) oestrogen screen; Y(A)AS: Yeast (anti-) androgen screen. The first axis is primarily determined by the sampling year. Data for 2012 to early 2014 (prior to the WWTP upgrade) are shown on the right side of the left figure, those for data from late 2014–2016 (after the WWTP upgrade) on the left side. The second axis allowed for a distinction between the effluent of the secondary clarifier and the following treatment steps. The third axis separated the effluents of the sand filter and the additional activated carbon stage