Estudio de la degradación de colorantes azoicos mediante la combinación de un proceso foto-Fenton asistido con ferrioxalato y un proceso biológico anaerobio

Abstract

In this work, the degradation of three azo dyes Drimaren Blue HF-RL, Drimaren Yellow CL-2R and Direct Red 4BS was studied using a ferrous oxalate mediated photo-Fenton system. The effect of three concentrations of reagents was analyzed: ferrous sulfate heptahydrate, oxalic acid dihydrate and hydrogen peroxide, and then the effect of pH on degradation rate constant of each dye. Next, the ferrous oxalate mediated photo-Fenton system was compared with a traditional photo-Fenton process to reduce COD, color and TOC of a textile effluent. In addition, an anaerobic biological process took place. It was tested feed streams to the reactor, so that the physicochemical parameters were compared with discharge limits to natural water sources. The decolorization obeyed a pseudo-first order kinetics. The concentrations of reagents selected according to the greater rate constant were 0,45 mM of ferrous sulfate heptahydrate, 0,45 mM of oxalic acid dihydrate and 58 mM of hydrogen peroxide. The pH selected was equal to 4. The ferrous oxalate mediated photo-Fenton system achieved the greatest removal of contaminants. It reached 58,56 % of COD, 80,79 % of color and 22,26 % of TOC, 45 min after treatment. The anaerobic biological treatment was carried out with an inlet flow of 10 mL/min. The combined system, ferrous oxalate mediated photo-Fenton and anaerobic biological treatment, proved to be suitable for the removal of contaminants from the textile effluent as it allowed the removal of 88,97 % of the COD, 97,10 % of color, 58,47 % of TOC, the 79,03 % of BOD5, and 84,14 % of surfactants