“… 18 The method has been widely used in the treatment of wastewater from the printing, dyeing, smelting, and electroplating industries. 19–21 Especially, in the processes of treating some refractory organic pollutants in complex wastewater, electrochemical oxidation has been found to exhibit satisfactory removal effect. 22 …”
“… 18 The method has been widely used in the treatment of wastewater from the printing, dyeing, smelting, and electroplating industries. 19–21 Especially, in the processes of treating some refractory organic pollutants in complex wastewater, electrochemical oxidation has been found to exhibit satisfactory removal effect. 22 …”
“…:100 mL Electrolyte support: the amount of sodium nitrate (NaNO 3 ): 10 g/L Current density: 0.5 A/m 2 Direct current (color removal): 98.8% Alternating current (color removal): 100% (Othmani et al 2017 ) Brazil Electrocoagulation Wastewater: synthetic Dye 0 : 0.002% (w/v) pH: 7.0 Electrolyte support: 0.05 mol NaCl Time: 80 min Current: 0.01 A Temperature: 28 °C Electrodes: steel, aluminum, bronze Aluminum commercial electrode: color removal 84% Steel commercial electrode: color removal 90% Bronze commercial electrode: color removal 96% (Oliveira et al 2019 ) Thailand Electrocoagulation Wastewater: textile industry pH: 4.0 Time: 60 min, j: 300 A/m 2 Vol. : 500 mL Electrodes: Al Electrode area: 50 cm 2 Electrode distance: 15 mm COD removal: 71.9% Color removal: 96.3% (Prayochmee, Weerayutsil and Khuanmar, 2021 ) Turkey Electrocoagulation Wastewater: textile industry Electrodes: Fe-stainless steel pH: 8.27 Current: 0.8 A j: 20.78 mA/cm 2 Conductivity: 4080 µs/cm Time: 15 min Distance: 10 mm Color removal: 97.8% (Kahraman and Şimşek 2020 ) j: Current density Fig. 6 Coagulation and electrocoagulation mechanism for IB and IC removal …”
Section: Treatments For Indigo Removal and Denim Wastewatermentioning
The denim textile industry represents an important productive sector. It generates wastewater with low biodegradability due to the presence of persistent pollutants, which can produce toxic and carcinogenic compounds; therefore, wastewater treatment reduces risks to aquatic life and public health. This paper presents a review of 172 papers regarding textile industry wastewater treatment for the removal of contaminants, especially indigo dyes used in the denim industry, in the context of green technologies. The physicochemical characteristics of textile wastewater, its environmental and health impacts, and the permissible limit regulations in different countries were reviewed. Biological, physicochemical and advanced oxidation processes for the removal of indigo dyes were reviewed. The goal of this study was to analyze the characteristics of green technologies; however, the research does not clearly demonstrate an effect on energy consumption savings, carbon footprint decreases, and/or waste generation. Advanced oxidation processes showed the highest color removal efficiency (95 and 97% in synthetic or real wastewater, respectively). Photocatalysis and Fenton reactions were the most efficient processes. None of the revised works presented results regarding upscaling for industrial application, and the results should be discussed in terms of the guidelines and maximum permissible limits established by international legislation. New technologies need to be developed and evaluated in a sustainable context with real wastewater.
“…Therefore, the increase in current density emphasizes electrode dissolution and the production of metal hydroxide during the electrochemical treatment (Bener et al, 2019). Furthermore, it was reported that both current and electrolysis time affect the operational cost by a study performed on the electrochemical treatment of denim production facility wastewater registering an energy consumption of 0.213 $/m 3 at a pH of 8.27, the current intensity of 0.8 A, and treatment time of 15 min (Kahraman & S ¸ims ¸ek, 2020).…”
Section: Energy Consumption Of the Processmentioning
The presence of reactive dyes in textile wastewater is a serious environmental concern due to their associated mutagenic and carcinogenic effects. The present study aims to analyze the effect of different anodic materials on the decolorization of a real textile wastewater effluent. For this purpose, four different anodic materials—TiO2‐coated platine, TiO2‐coated ruthenium dioxide (RuO2) (viz., RuO2), titanium dioxide (TiO2), and graphite—were connected, respectively, to titanium dioxide (TiO2) used as a cathode electrode. Color and cost optimization studies were performed using the response surface methodology and the Box–Behnken experimental design (BBD). According to ANOVA results, the R2 values for Pt/TiO2, RuO2/TiO2, TiO2/TiO2, and graphite/TiO2 electrode pairs were found to be 97.4%, 93.8%, 92.44%, and 92.2%, respectively, indicating a good compatibility as it is close to one. The results show that color removal efficiencies at the optimal conditions were 86.3%, 90.8%, 91.5%, and 93.6% for Pt/TiO2, graphite/TiO2, TiO2/TiO2, and RuO2/TiO2, respectively. Furthermore, energy consumption cost at the optimum conditions was also evaluated, and the results were as follows: Pt/TiO2 (0.95 €/m3), graphite/TiO2 (0.74 €/m3), TiO2/TiO2 (0.31 €/m3), and RuO2/TiO2 (0.26 €/m3). Consequently, this research paper shows that all of the tested anodic materials give satisfactory color removal efficiencies higher than 86%. When energy consumption and color removal are considered together, the use of TiO2/TiO2 and RuO2/TiO2 pairs would be preferred.
Practitioner Points
Anodic contribution was investigated for decolorization of textile wastewater by electrooxidation process.
Graphite, TiO2‐coated Pt, TiO2‐coated RuO2, and TiO2 were used as anode materials.
Highest color removal with lowest energy consumption was achieved with TiO2‐coated RuO2 anode material (93.6%).
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