Harvesting properties of two cationic tannin-based flocculants
were investigated on the samples of the HRAP mixed liquor. Ecotan
AR® (Servyeco, Spain) and Tanfloc SG® (Tanac SA, Brazil) are natural
cationic flocculants extracted from the bark of Acacia mearnsii having
strong coagulating properties. None of the flocculants modifies
the pH of the medium significantly and both of them are effective
over a pH range of 4.5–8 (9 for Ecotan). Ecotan was provided in liquid
form with a concentration of 0.3 g/L, while Tanfloc was supplied as a
dry product that was dissolved in water until complete solution. Both
flocculants are suitable for wastewater treatment applications, and
were conceived to replace metal-based products with aluminum and
iron chlorides.