Estudo do uso do lodo de estação de tratamento de água na reação de Fenton

Abstract

The present work had as main objective the accomplishment of an evaluation of the use of the sludge of the decantation tank of a water treatment plant, as an iron source in reactions of the Fenton type, to reduce organic matter and color in aqueous medium. The research was carried out with the methylene blue dye (MB) as a model molecule at concentrations of 1.500 and 50 mg/L as effluent. The study initially addressed the characterization of the study site and the SWTP (sludge from water treatment plant). Subsequently, the exploratory step was carried out, which consisted of carrying out tests of the Fenton reaction, in the sequence three preliminary studies were carried out, being: 1º) reaction white without the addition of hydrogen peroxide (H2O2); 2º) the concentrations of SWTP, MB solution and H2O2 were investigated; and 3º) the concentrations of SWTP, MB solution, H2O2 and the process time of the Fenton reaction were investigated. Finally, factorial planning was carried out, according to the best performance of the preliminary studies. The result of the SWTP characterization showed a large amount of organic matter and high iron content. The exploratory stage, based on its results, allowed to adjust the treatment conditions for the Fenton reaction. The three preliminary studies made it possible to arrive at a satisfactory result for the Fenton reaction, with the best experimental condition in the MB reaction medium = 1.500 mg/L, SWTP = 20,7 mg/L, H2O2 = 1,75 mg/L and time reaction time 30, 60 and 180 minutes. Regarding the color change, the highlighted conditions were: 50 mg/L of MB, 0,95 mg / L of SWTP and 1,75 mg/L of H2O2 with removal above 90%. The factorial design showed the best result in removing COD with 91,8%, in the condition of MB = 1.500 mg/L, SWTP = 20,7 mg/L, H2O2 = 1,75 mg/L and reaction time 180 minutes and for this same condition with the lowest concentration of MB (50 mg/L) it showed COD removal in 49% and color change with 100% performance at 605 nm wavelength. Thus, studies have shown that the treatment of MB with the use of SWTP as a catalyst in the Fenton reaction, has shown promise in removing organic matter and degrading the dye. Thus, SWTP has a new alternative for its reuse.