Avaliação de um reator de fluxo contínuo para eletrofloculação do efluente da purificação do biodiesel.

Abstract

The biodiesel production plant stands out not only for the synthesis of a fully renewable product, the biodiesel itself, but the large amount of water used its the purification process, which results in production of large volumes of contaminated waste. Some alternatives for the treatment of such waste have been studied and applied, such as the electrochemical process called electroflocculation. However, the work reported in the literature so far has been carried out in batch reactors, which may be disadvantageous due to the large volume of wastewater produced in the process. Thus, the current analysis aims to study a continuous flow electrochemical reactor for electroflocculation of the waste from the biodiesel purification process. Then, it was developed a reactor with a total volume of 1.0340 L, in which four aluminum electrodes with dimensions of (10 x 6.40 x 0.10 cm) were inserted and connected to a CC power supply, and the reactor was settled in a treatment plant in bench scale. For operating the system, an artificial effluent with a standard concentration of 7,380 g.L-1, containing all the contaminants present in the actual effluent from biodiesel purification was synthesized. For this study it was developed an experimental design in order to assess the influence of the initial pH, space time and the potential difference over the variables that characterize the treated water, the consumption of the electrode mass and energy consumption of the reactor. An array of eleven experiments was performed and collected water samples in the range of 5.0 min for 40 min for characterization. The results were initially assessed for dynamic behavioral and it was observed that the best turbidity removal rates, COD and O&G were 94.21 %, 89.3 % and 51.2 %, respectively. From the statistical results, it was observed that the initial pH was the most active factor in the varying responses and the optimization analysis showed that the maximum reactor efficiency is achieved when operating with an initial pH of 8.0, a space time of 29.43 minutes and a potential difference of 6.0 Volts, resulting in an energy consumption of 4.8 kWh.m-3, which equals R$ 1.94 per cubic meter of treated effluent. Based on the results it was found that the application of the reactor is feasible to treat the waste from the biodiesel purification, regarding to the contaminant removal efficiency, energy consumption and the volume of treated effluent.