It is relevant that without flocculant addition the velocities obtained along the column were fairly constant (0.05–0.08 mm/s) and much lower than those obtained with flocculated samples (0.21–0.56 mm/s with Ecotan and 0.16–0.35 mm/s with Tanfloc). Comparing flocculants, higher velocities along the column (with a maximum of 0.56 mm/s at 40 cm), were obtained with Ecotan (10 mg/L). In contrast, higher doses of Tanfloc (50 mg/L) yielded slower settling velocities of about 0.35 mm/s. A conventional gravity settler should be designed in order to retain 90% of the biomass with a surface loading rate of 0.3 mm/s [23]. Considering the settling velocities obtained in this study (Table 4), a velocity of 0.3 mm/s was obtained at column depths of 20 and 30 cmfor Ecotanand Tanfloc, respectively. Therefore, settler surface area with Ecotan would be 2-times smaller than Tanfloc and 8-times without flocculant.