Estudo sobre os processos de coagulação, floculação e decantação em efluentes oriundos de usina canavieira

Abstract

The main residue from processing sugarcane at sugar-alcohol industry is the vinasse. It consists of an effluent with characteristics 100 times more pollutant than domestic sewage and it is generated in huge volumes, at a ratio of 10 to 15 liters of vinasse per liter of ethanol producted. Due to the huge amounts of vinasse generated at distilleries and due to favorable perspectives of ethanol production at Brazilian scenario, several projects have been proposed in order to decrease environmental impacts caused by inadequate discard of this effluent. The current study aims to promote vinasse treatment so that the impacts caused by inappropriate discard be minimised, thus even enabling reuse of this effluent. In this context, vinasse treatment by means of physicochemical processes of coagulation, flocculation and decantation in jar test was chosen, utilising unnatural coagulants – ferric chloride and aluminium sulfate – and natural coagulant – Tanfloc SG. Tests of pH, colour, turbidity, solids and volatiles solids were made. Results showed that unnatural coagulants did not succeed on vinasse treatment, unlike what has happened with Tanfloc SG. The natural coagulante utilised reached rates of 90% off colour removal and 98% of turbidity removal.