The metalworking industry is responsible for one of the most complex and difficult to handle oily effluents. These effluents consist of cutting fluids, which provide refrigeration and purification of metallic pieces in the machining system. When these effluents are biologically treated, is important to do this with autochthonous microorganisms; the use of these microorganisms (bioaugmentation) tends to be more efficient because they are already adapted to the existing pollutants. For this purpose, this study aimed to use two indigenous microorganisms, Epicoccum nigrum and Cladosporium sp. for metalworking effluent treatment using an air-lift reactor; the fungus Aspergillus niger (laboratory strain) was used as a reference microorganism. The original effluent characterization presented considerable pollutant potential. The color of the effluent was 1495 mg Pt/L, and it contained 59 mg/L H2O2, 53 mg/L total phenols, 2.5 mgO2/L dissolved oxygen (DO), and 887 mg/L oil and grease. The COD was 9147 mgO2/L and the chronic toxicity factor was 1667. Following biotreatment, the fungus Epicoccum nigrum was found to be the most efficient in reducing (effective reduction) the majority of the parameters (26% COD, 12% H2O2, 59% total phenols, and 40% oil and grease), while Cladosporium sp. was more efficient in color reduction (77%).
The objectives of this paper were: to perform the physical-chemical characterization of a metalworking effluent and to carry out the integrated treatment (chemical precipitation and biotreatment), using effluent autochthonous microorganisms (FI and FV) and a reference (A. niger). The characterization indicated pH of 1.7; color, 1,495 mg Pt.L-1; chemical oxygen demand, 9,147 mgO2.L-1; oil and grease, 887 mg.L-1, and dissolved oxygen with 2.5 mgO2.L-1. With the chemical precipitation treatment, in pH = 7.5, the reduction of all the investigated metallic ions was obtained. The color was reduced 95% after the biotreatment using the FV microorganism. The chemical oxygen demand and oil and grease reductions were more significant when using FI, which reduced the same in 52 and 62%, respectively. These results indicated that the autochthonous microorganisms were more efficient in the effluent treatment than the reference organism A. niger.
Os objetivos deste trabalho foram: realizar a caracterização físico-química de um efluente metal-mecânico e efetuar o tratamento integrado (precipitação química e biotratamento), utilizando micro-organismos autóctones do efluente (FI e FV) e uma referência (A. niger). A caracterização indicou pH de 1,7; cor de 1.495 mg Pt.L-1; demanda química de oxigênio de 9.147 mgO2.L-1; 887 mg.L-1 de óleo e graxa, além de 2,5 mgO2.L-1 de oxigênio dissolvido. Com o tratamento por precipitação química, obteve-se, em pH = 7,5, a redução de todos os íons metálicos investigados. Após o biotratamento, a cor foi reduzida em 95%, utilizando o micro-organismos FV. As reduções da demanda química de oxigênio e de óleo e graxa foram mais significativas utilizando FI, que reduziu os mesmos em 52 e 62%, respectivamente. Estes resultados indicaram que os micro-organismos autóctones do efluente foram mais eficazes no tratamento do mesmo do que o organismo de referência A. niger.