Tratamento de água para consumo humano utilizando processo de eletrocoagulação

Abstract

Electrochemical processes are of great importance in water treatment studies because of their positive aspects of operation, costs, advantages in using relatively small areas and the non addition of chemicals. The objective of this paper was to study the efficacy of electrocoagulation in the clarification of water for human consumption using aluminum electrodes. This treatment consists in generating coagulating species in situ by electrolytic oxidation of the anode via an electrical current applied through the electrodes sacrifice. For this, raw water samples were collected from the surface spring of the Tidal Water Treatment Station of Companhia de Água e Esgotos da Paraíba (CAGEPA). The experiments were performed in a reactor equipped with three aluminum electrodes with bipolar arrangement and series connection, connected to a source of direct current of 12V. From preliminary tests were performed 11 experiments with the reactor, starting from a 2³ factorial planning with central point. There was variation of the electrolysis time from 10, 25 and 40 minutes, electric conductivity of 500, 1250 and 2000 S/cm, and pH of 5, 7 and 9, keeping the constant distance between the electrodes. Analyzes were performed before and after the treatment to evaluate the behavior of the parameters color, turbidity, pH and aluminum. In addition, the treated water was filtered to remove residual aluminum that was generated in the process. In general, removal efficiencies greater than 90% were observed for both color and turbidity, setting these parameters within the required potability standards. Based on experiments it was possible to get great conditions of treatment for water clarification, and these conditions met for electric conductivity of 2000 S/cm, a time of 40 minutes of electrolysis and a pH equal to 5, obtaining 93 % in the removal of the turbidity. In the case of electric conductivity of 500 S/cm, 40 minutes electrolysis and pH equal to 9 it was reached 100 % removal of true color and apparent