In this study, photo-Fenton systems using visible light sources with iron and ferrioxalate were tested for the DOC degradation and decolorization of textile wastewater. Textile wastewaters originated after the dyeing stage of dark-colored tissue in the textile industry, and the optimization of treatment processes was studied to produce water suitable for reuse. Dissolved organic carbon, absorbance, turbidity, anionic concentrations, carboxylic acids, and preliminary cost analysis were performed for the proposed treatments. Conventional photo-Fenton process achieved near 99 % DOC degradation rates and complete absorbance removal, and no carboxylic acids were found as products of degradation. Ferrioxalate photo-Fenton system achieved 82 % of DOC degradation and showed complete absorbance removal, and oxalic acid has been detected through HPLC analysis in the treated sample. In contrast, photo-peroxidation with UV light was proved effective only for absorbance removal, with DOC degradation efficiency near 50 %. Treated wastewater was compared with reclaimed water and had a similar quality, indicating that these processes can be effectively applied for textile wastewater reuse. The results of the preliminary cost analysis indicated costs of 0.91 to 1.07 US$ m for the conventional and ferrioxalate photo-Fenton systems, respectively. Graphical Abstract ᅟ.

The textile industry is responsible for generating a large amount of a very complex wastewater during its production process. This wastewater contains residual dyes, high concentration of salt, soaps and detergents. Also, dyes used in the process are soluble in water, but not biodegradable and may be toxic for the environment. The present work proposes using advanced chemical oxidation (AOP) applying the photo-Fenton process in order to evaluate the feasibility of water reuse in the textile industry production process. Reactions were conducted in a bench photo-reactor with radiation, both UV and UV-vis and testing Iron Sulfate and Ferrioxalate as Iron (II) sources. Also, an experimental design was followed in which initial concentrations of Fe(II) and H 2 O 2 varied from 4-20 mg/L and 100-500mg/l, respectively. Response variables monitored were TOC (mg/L) and residual H 2 O 2 (mg/L). For a pH equals 3 in a molar rate of Fe/H 2 O 2 ≈ 0,4:3, TOC reduction obtained was 98,4% and residual concentration of H 2 O 2 was 2,6 mg/l. Results favor textile wastewater reuse after AOP treatment.

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