APLICAÇÃO DA TÉCNICA DE ELETROFLOCULAÇÃO PARA O TRATAMENTO DO EFLUENTE DO BIODIESEL

Abstract

The biodiesel production process consists of the following steps: preparation of the raw material, transesterification reaction, phase separation, glycerin distillation and purification, with washing water as the residue. The washing water generated during purification has a high content of oils and greases, having the potential to contaminate bodies of water. One of the treatment proposals is to use the electrofloculation technique because of its effectiveness during the treatment process. The objective of this work is to apply the electrofloculation technique with different electrodes aiming at the best condition of treatment time and applied voltage. The process was carried out in an electrochemical reactor composed of two electrodes. The electrodes used were Aluminum (Al), Carbon Steel (C. Steel), Galvanized Carbon Steel (G. C. Steel), Tin (Sn) and Zinc (Zn) with total contact area of the electrodes in the effluent of 144 cm2L-1. The distance between the electrodes was set at 10 mm. Different stresses and test times were applied in order to determine the best process parameters. The best voltage for each electrode was 3 volts for Al and Steel C., and 4 Volts for Steel C. G, Zn and Sn, and the time was 45 minutes for each electrode. To remove the supernatants from the treated effluent, two filtration techniques were used, the first one with filter paper and the second with activated carbon filter. The activated carbon filter was the one that presented the best removal of pollutants, with removal efficiency of 58% of COD with Steel C electrode and 56% with Zn electrode. For the removal of BOD, the efficiency was 96% for the electrodes of Al, Steel C, and Steel C. G. The cost for the application of the electro-flocculation technique did not exceed the value of 9,71 R$/m3. The lowest operating costs were using the electrode Al and Steel C. which cost respectively 7,55 R$/m3 and 7,45 R$/m3. Due to the results, it can be concluded that it is possible to use the technique of electrofloculation in the treatment of biodiesel effluent in technical-economic terms using different electrodes.