Hybrid process combining ultrafiltration and electro-oxidation for COD and nonylphenol ethoxylate removal from industrial laundry wastewater

• Published in: Chemosphere (Oxford) 2024-09, Vol.363, p.142931, Article 142931
• Main Authors: Khajvand, Mahdieh, Drogui, Patrick, Arab, Hamed, Tyagi, Rajeshwar Dayal, Brien, Emmanuel
• Format: Article
• Language: English
• Subjects: Electro-oxidation; Endocrine disruptors; Laundry wastewater; Nonylphenol ethoxylates; Reuse; Ultrafiltration
• ISSN: 0045-6535; 1879-1298; 1879-1298
• DOI: 10.1016/j.chemosphere.2024.142931

Laundry wastewater is a significant source of nonylphenol ethoxylate (NPEO) at wastewater treatment plants, where its breakdown forms persistent nonylphenol (NP). NP poses risks as an endocrine disruptor in wildlife and humans. This study investigates the degradation of NPEO and COD in industrial laundry wastewater (LWW) using a two-stage process combining ultrafiltration (UF) and electro-oxidation (EO). UF was used to remove suspended solids, while soluble COD (COD0 = 239 ± 6 mg.L−1) and NPEO (NPEO0 = 341 ± 8 μg.L−1) were oxidized by the EO process. Different operating parameters were studied such as current density, electrolysis time, type of cathode and supporting electrolyte concentration. Using an experimental design methodology, the optimal conditions for COD and NPEO3-17 degradation were recorded. This included achieving 97% degradation of NPEO3-17 and 61% degradation of COD, with a total operating cost of 3.65 USD·m−3. These optimal conditions were recorded at a current density of 15 mA cm−2 for a 120-min reaction period in the presence of 4 g·Na2SO4 L−1 using a graphite cathode. The EO process allowed for reaching the guidelines required for water reuse (NPEO