Enhanced electrooxidation/electrocoagulation-ultrafiltration membrane process with S₂O₄^2- for saline algae-containing...

The surface water in coastal areas involving algae, is often affected by saline and emerging contaminants caused by saltwater intrusion, and expanding aquaculture industry. Therefore, it is necessary to conduct studies to address the issues that affect ecological safety and health of aquatic environments. This study presents the development of an enhanced electrooxidation/electrocoagulation-ultrafiltration (EO/EC-UF) membrane process using S₂O₄^2- (DTN@EO/EC-UF) for the treatment of saline water containing algae. Our results have shown that significant removal of NH₃-N (95.1 %), UV₂₅₄ (89.4 %) and algae (75.7 %) was achieved with the addition of S₂O₄^2- (DTN). Additionally, an optimal DTN dosage of 40 mg/L was used in the DTN@EO/EC process to enhance water purification, utilizing reactive species such as SO₄^·- and ·OH. After coupling with the ultrafiltration (UF) process, optimal operating conditions (DTN: 40 mg/L, current density: 4.65 mA/cm², electrolysis: 60 s) were applied to treat the saline algae-containing surface water. The generated free chlorine, including NHCl₂, accounted for approximately 22 % (0.14 mg/L). In addition, DTN significantly improved the ceramic membrane's permeability and anti-fouling characteristics, with a maximum increasing specific flux from 0.76 to 0.93, mainly attributing to the reduced the irreversible fouling resistance. Furthermore, we discovered that common membrane cleaning using acid or base enhanced the DTN@EO/EC-UF process. In conclusion, this study established an innovative DTN@EO/EC-UF process with excellent performance in terms of water purification and membrane self-cleaning. The results provided a promising alternative for treating saline algae-containing surface water.