Tratamento eletroquímico e físico-químico para efluente de lavanderia industrial têxtil

Abstract

The textile industrial laundry is characterized by the variety of existing processes, the large volume of wastewater and high polluting load. Physical and chemical characterization of these effluents is important to determine the appropriate treatment and to assess pollutants and their potential impacts. Thus, the development of this study allows contribute to the knowledge of the electrochemical processes and physical chemistry in order to remove the color and organic load in textile industrial laundry wastewater. The experiments were performed in four processes: - 1: electrocoagulation / electroflocculation / electrocoagulation tests using reactor at laboratory scale stirred tank with the use of aluminum and carbon electrodes. - 2: physico-chemical tests using process by dissolved air flotation (DAF) with a bench scale unit (flotatest) using tannin "Tanfloc SG". - 3: tests DAF using polyaluminum chloride (PAC) and anionic polymer. - 4: tests DAF using seeds of Moringa oleífera. The methodology used for the testing of all processes was the experimental design central composite rotational design (RCCD) with two parameters assessed for each process: - 1: electric current and electrocoagulation time; - 2: tannin dosage as coagulant and pH solution; - 3: PAC dosage as coagulant and anionic polymer; - 4: moringa dosage as coagulant and pH solution. At the end of the tests, samples of treated wastewater were analyzed to determine the removal efficiency of apparent color, turbidity, chemical oxygen demand (COD) and total suspended solids (TSS). In the process 1, optimal efficiency the electrochemical of process for the removal of apparent color, turbidity, COD and TSS 86%; 58.93%; 75.2% and 66.3%, respectively. For the DAF tests, the maximum efficiency for the removal of apparent color, turbidity, COD and TSS for process 2 was 90%; 96.90%; 61.4% and 94.1%, respectively, for process 3 was 93%; 93.65%; 71.8% and 88.8%, respectively; and for process 4 was 65%; 80.00%; 40.2% and 62.3%, respectively. The results indicated that only the experiment using the DAF process with the moringa oleífera coagulant was not a viable option, because it exceeds the quality standard of the apparent color required by the resolution CONAMA 357. The processes and coagulants studied in this work can be used as technically feasible alternatives to removal apparent color, turbidity, COD and TSS of textile industrial laundry wastewater.