Utilização da eletrocoagulação no tratamento de efluente da indústria galvânica

• Autor(a) principal: Theodoro, Paulo Sérgio
• Data de Publicação: 2010
• Tipo de documento: Dissertação
• Idioma: por
• Título da fonte: Biblioteca Digital de Teses e Dissertações do UNIOESTE
• Texto Completo: http://tede.unioeste.br:8080/tede/handle/tede/1891
• topic: Eletrofloculação; Efluente de indústria galvânica; Planejamento experimental; Parâmetros físico-químicos; Metais; Efluentes industriais - Tratamento; Indústria galvânica - Tratamento de efluentes; Eletrocoagulação; Águas residuais - Purificação; Metais pesados - Remoção; Resíduos industriais - Galvanoplastia; Electro-coagulation; Galvanic industry effluent; Experimental design; Physico-chemical parameters; Metals; CNPQ::ENGENHARIAS::ENGENHARIA SANITARIA::TRATAMENTO DE AGUAS DE ABASTECIMENTO E RESIDUARIAS::ESTUDOS E CARACTERIZACAO DE EFLUENTES INDUSTRIAIS

The aim of this work is devoted to reduction of the environmental impact of galvanic industry effluents. An electro-coagulation (EC) laboratory scale system using iron plates electrodes was studied for the removal of organic and inorganic pollutants as a by-product from the treatment of galvanic process based-platining industry. An EC reactor consisting of a 1,5 L conical container and a set of seven firmly assembled iron electrode plates, which were parallelly arranged to each other and electrically operated in mono-polar mode, was built. A 1.0 cm gap between the anode and cathode plates using a non-conducting horizontal support was chosen in order to operate the EC reactor in a low electrical current range. A long, electrical rotating cilindrical rotor, with 2,7cm blades at the end of it, made in non-conducting material, was used to turn mechanically the effluent around the rotor axis during the EC treatment. In addition, a 225 cm2 active electrode surface area was kept during the whole EC experiments. In order to obtain optimal values of reaction time, electrical current, rotor angular velocity, and initial effluent pH, a central composite rotatable design (CCRD) was applied. A wide range of reaction time (10-60 min), electrical current (0.3-3.0 A), rotor angular velocity (50-300 rpm), and initial efluent pH (3-10) were used, performing a total of 28 runs with 24+2x4 axial points and 4 central points. Physico-chemical parameters such as chemical oxygen demand (COD), color, turbidity, total solids, and metals (Cr, Ni, Zn, and Cu) were used as response variables. The measurements of physico-chemical parameter and metal concentration values in non- and treated waste waters were carried out by applying the Standard Methodology and the Synchrotron Radiation X-Ray Fluorescence (SR-TXRF) technique, respectively. Using the Statistica software, a 95%-significance level (p<0.05) of the predicted models and interaction effects between reactor operating variables on response variables were evaluated using 3-D response surface curves and analysis of variance. With the factorial design was obtained the following optimum conditions of the reactor, 35 minutes for the time of electrolysis, 170 rpm for agitation, 2.2 A for the electric current and 6.5 for pH. Under these conditions the removal of color and turbidity reached 100%, another considerable value was the removal of around 90% of COD and total solids. Moreover, a removal of around 99% of Zn and Cu was obtained, whereas for Cr and Ni obtained a removal of 100%. Finally, the results of technical and economic analysis showed the cost obtained by the treatment, indicating clearly that the method of electro-coagulation is very promising for industrial application.