Textile wastewater reuse after additional treatment by Fenton’s reagent

Abstract

This study verifies textile wastewater reuse treated by the conventional activated sludge process and subjected to further treatment by advanced oxidation processes. Three alternative processes are discussed: Fenton, photo-Fenton, and UV/HO. Evaluation of treatments effects was based on factorial experiment design in which the response variables were the maximum removal of COD and the minimum concentration of residual HO in treated wastewater. Results indicated Fenton's reagent, COD/[HO]/[Fe] mass ratio of 1:2:2, as the best alternative. The selected technique was applied to real wastewater collected from a conventional treatment plant of a textile mill. The quality of the wastewater before and after the additional treatment was monitored in terms of 16 physicochemical parameters defined as suitable for the characterization of waters subjected to industrial textile use. The degradation of the wastewater was also evaluated by determining the distribution of its molecular weight along with the organic matter fractionation by ultrafiltration, measured in terms of COD. Finally, a sample of the wastewater after additional treatment was tested for reuse at pilot scale in order to evaluate the impact on the quality of dyed fabrics. Results show partial compliance of treated wastewater with the physicochemical quality guidelines for reuse. Removal and conversion of high and medium molecular weight substances into low molecular weight substances was observed, as well as the degradation of most of the organic matter originally present in the wastewater. Reuse tests indicated positive results, confirming the applicability of wastewater reuse after the suggested additional treatment. Graphical abstract Textile wastewater samples after additional treatment by Fenton's reagent, photo-Fenton and HO/UV tested in different conditions.

Heterogeneous photocatalytic degradation of anthraquinone dye Reactive Blue 19: optimization, comparison between processes and identification of intermediate products

“…Approximately 10 000 different synthetic dyes are available in the market and worldwide annual production of these dyes is over 700 000 t. Nearly 200 000 t of synthetic dyes are lost into the environment because of the inefficient dyeing process used in textile industries. According to World Bank estimates, about 17-20% of industrial wastewater is generated from textile dyeing and finishing treatments (Holkar et al, 2016;Hossain et al, 2018;Ribeiro et al, 2017).…”

Investigating degradation metabolites and underlying pathway of azo dye “Reactive Black 5” in bioaugmented floating treatment wetlands

“…6). As observed, three major reactions, namely, the conversion of double into single bonds, break of azo bonds, and detachment of sulfonic groups, along with the addition of H-atoms are involved in the degradation of RB5, which indicates that RB5 degradation proceeds through a reductive pathway (Ribeiro et al 2017;Hasanin 2020). Particularly, the detachment of sulfonic mediety from the parent compound formed product 3 (when one -SO 3 Na group is cleaved) and product 5 (when both -SO 3 Na groups are eliminated).…”

“…Therefore, the comprehensive description of the biodegradation products and intermediates of synthetic dyes has a signi cant role in the assessment of the ecological fate of these contaminants (Ribeiro et al 2017;Hasanin 2020).…”

Recent Achievements in Dyes Removal Focused on Advanced Oxidation Processes Integrated with Biological Methods

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