DESENVOLVIMENTO DO TRATAMENTO DE EFLUENTE PARA RESÍDUO LÍQUIDO GERADO EM PROCESSOS DE PINTURA ELETROSTÁTICA DE ALUMÍNIO

Abstract

In this work, chemical precipitation was used with the addition of different amounts of calcium hydroxide and sodium hydroxide in the treatment of the effluent the aluminum and electrostatic painting industries, to verify the best visual result (clearness and decantation of the sludge) and to compare the results of the liquid waste before and after the chemical treatment. It was noticed that the treatment occurs more efficiently with the addition of calcium hydroxide at pH 5.0 to 6.0, as the effluent showed greater clarity, faster decantation of the sludge, when compared to smaller additions of the same. Based on these tests, comparative analyzes were carried out between the raw effluent and the treated effluent, after chemical precipitation, discussing the parameters pH, total aluminum, dissolved cuprum, total ammoniacal nitrogen and biological oxygen demand (BOD) and comparing the standards of resolutions nº 357 and 430 of CONAMA and nº 181 and 189 of CONSEMA. The results of the analysis of the treated effluent obtained pH 7.96, aluminum 7.964 mg/L, cuprum 0,009mg/L, total ammoniacal nitrogen 1,8mg/L and BOD 5,3mg/L. Except aluminum (parameter 0.1 mg/L), the other metals, BOD and pH are within the specified parameters. Despite the comparison with the legislation, all tests had a reduction of more than 90% of pollutants, that is, the reduction of aluminum concentrations by 99.56%, cuprum by 99.1%, ammoniacal nitrogen by 95.95% and the BOD in 91.88%, achieving the proposed objective and determining that using chemical precipitation in the effluent treatment proved to be an effective method.