As can be seen by comparing Figs. 4, 5 and 6, samples with an opti-mal dose of Ecotan (Fig. 5) and Tanfloc (Fig. 6) had much more higher settlingvelocities than samples without flocculant(Fig. 4). For instance, without flocculant, 90% of the biomass was settled at port d4 = 40 cm after 80 min by adding (Fig. 4), while after Ecotan and Tanfloc addition, 90–95% biomass recovery took place after less than 20 and 10 min, re-spectively (Figs. 5 and 6).