Avaliação da eficiência do processo eletroquímico no tratamento do efluente de uma fábrica de sorvetes

Abstract

The effluents of the dairy products industries have as its main characteristic a large amount of organic material, which makes the treatment difficult, needing to go through several processes and steps generating a high operational cost. In this perspective it was decided to develop na electrochemical system for the treatment of this effluent using DSA as electrodic material. The system was composed of a vertical reactor with the electrodes positioned at the base of the reactor, forming a floating region just above the electrodes. The system operated in continuous flow and batch. In this study were used commercial DSA® (Ti/Ru0.34Ti0,66O2) of 7 x 6 cm, a reactor with a treatment capacity of 3.8 L effluent, and Na2SO4 0.1 mol L-1 as the support electrolyte. Initially, the hydrodynamic behavior of the continuous flow reactor was evaluated, where peak concentration of the indicator was observed, representing the formation of dead zones leading to a nonlinear flow. In the experimental design evaluating the influence of the current density, flow and effluent concentration on the COD and turbidity as response variables, it was found that the current density and the interaction current and concentration are the most significant variables. Under optimized conditions of current density of 20 mA cm-2, effluent concentration of 2g L-1 and a flow rate of 370 mL s-1, a maximum reduction of 84.67% COD and 84.66 turbidity was obtained after 2 hours of reaction in continuous flow. In batch the average efficiency for COD and turbidity reduction was 71.42 and 82.57%, respectively. In the study as a function of reaction time, for both response variables, there was an increase in efficiency in reducing of turbidity and COD tending to remain constant after 60 and 90 minutes of reaction, respectively, indicating reaching equilibrium between the reactor feed flow and the kinetic race of the treatment. Treatment efficiency in both continuous and batch flow was associated with the electroflotation / electrooxidation system. In addition to being efficient, the system proved to be economically viable with an estimated electrical consumption of 1.3104 kWh m-3 under optimized conditions.