Efficient treatment for textile wastewater through sequential electrocoagulation, electrochemical oxidation and adsorption processes: Optimization and toxicity assessment

• Published in: Journal of electroanalytical chemistry (Lausanne, Switzerland) Switzerland), 2020-12, Vol.878, p.114578, Article 114578
• Main Authors: GilPavas, Edison, Dobrosz-Gómez, Izabela, Gómez-García, Miguel-Ángel
• Format: Article
• Language: English
• Subjects: Activated carbon; Adsorption; Algorithms; Anodes; Artemia; BDD anode; Biodegradability; Boron; Cathodes; Coupling (molecular); Degradation; Design of experiments; Design optimization; Diamonds; Effluents; Electro-oxidation; Electrochemical oxidation; Electrocoagulation; Electrolysis; Energy consumption; Industrial textile wastewater; Industrial textiles; Low molecular weights; Molecular weight; Molecular weight distribution; Optimization; Oxidation; Reagents; Sludge; Toxicity
• ISSN: 1572-6657; 1873-2569
• DOI: 10.1016/j.jelechem.2020.114578

In this work, the sequential Electrocoagulation + Electro-oxidation + Activated carbon adsorption (EC + EO + AC) process was studied as an alternative for the treatment of an industrial textile wastewater (TWW) issuing from a manufacturing company located in Medellín (Colombia). The EC's and EO's operational conditions were optimized using a Box-Behnken experimental design, the Response Surface Methodology and a constrained nonlinear optimization algorithm in terms of organic matter degradation efficiency. The best performance for EC (i. e., dye removal = 94%, COD and TOC degradation of 45 and 40%, respectively) was obtained using Fe anode and Boron Doped Diamond (BDD) cathode, with current density, jEC, equals to 5 mA/cm2, pH = 9.3, 60 RPM and 10 min of electrolysis. After EC treatment, the effluent biodegradability (evaluated as the BOD5/COD ratio) increases from 0.14 to 0.23. Regrettably, EC was not effective for the removal of acute toxicity to Artemia salina since the treated effluent remained very toxic (100%). The treatment of EC's effluent by EO enhanced organic pollutant removal. For EC + EO sequential process, EO optimal operational conditions (jEO = 10 mA/cm2, pH = 3, 240 RPM, BDD as anode and Fe as cathode) allowed reduction of 100% of color, 88% of COD and 79% of TOC after 30 min of electrolysis. Moreover, the BOD5/COD ratio increased from 0.23 to 0.58; however, the treated effluent remained very toxic to the Artemia salina. Consequently, an activated carbon adsorption step was included to complete the treatment process. Thus, by coupling the EC + EO + AC process, effluent's acute toxicity decreased completely. From molecular weight distribution analysis, it was concluded that EC + EO was efficient in eliminating low molecular weight (< 5 kDa) compounds. Finally, the operation cost, which includes chemical reagents, electrodes, energy consumption, and sludge disposal, for the EC + EO + AC sequential process was estimated in 3.83 USD /m3. Graphical abstract [Display omitted]