Tratamento do efluente de indústria cosmética por eletrocoagulação em reator eletroquímico cilíndrico em fluxo ascendente contínuo

Abstract

The application of electrocoagulation (EC) for the treatment of cosmetic effluents considered to be commonly toxic and of low biodegradability has shown satisfactory results, however, most studies focus on batch experiments with the application of technologies complementary to EC. In this sense, this research sought to evaluate the influence of operational parameters initial pH, electric current density, conductivity and hydraulic retention time (HRT) of a cylindrical electrochemical reactor in continuous upward flow (REC-FAC) for the treatment of cosmetic effluent. A Fractional Factorial Planning 24-1, composed of 12 tests, was used to verify the influence of operational parameters. The results demonstrated at a 90% confidence level (p - value <0.10), that the parameters HRT, density of electric current and conductivity are significant in the treatment of cosmetic effluent by EC in the REC-FAC. Thus, a DCCR 23 that considered only significant operational parameters was applied. To the results of the COD responses, turbidity and residual Al concentration of DCCR 23, the global desirability function, considering the significant effects in the 95% confidence interval, was applied and the optimal treatment values of the independent variables were identified, these being: HRT (5 min), j (5 mA cm-2) and conductivity (2,000 S cm-1) for the REC-FAC. Under these conditions, the EC treatment through REC-FAC, reached removals of 61.96% of COD and 44.71% of turbidity, and 33.54 ± 1,82 mg L-1 of residual Al concentration, with an operational cost equal to 0.96 R $ m-3. The reduced HRT and density of electric current required by the reactor that operated in continuous flow, is a positive indication of the proposed design and represents an advance, compared to works reported in the literature. Thus, these results encourage the applicability of EC technology in the REC-FAC, as a promising alternative for the treatment of effluents from the cosmetic industry.