Polymer-flooding produced water treatment using an electro-hybrid ozonation-coagulation system with novel cathode membranes targeting alternating filtration and in situ self-cleaning

• Published in: Water research (Oxford) Vol. 233; p. 119749
• Main Authors: Jin, Xin, Li, Keqian, Wei, Yixiong, Shang, Yabo, Xu, Lanzhou, Liu, Mengwen, Xu, Lu, Bai, Xue, Shi, Xuan, Jin, Pengkang, Song, Jina, Wang, Xiaochang C.
• Format: Journal Article
• Language: English
• Published: England Elsevier Ltd 15.04.2023
• Subjects: Cathode membrane; Filtration - methods; In situ self-cleaning; Membrane fouling; Membranes, Artificial; Oxygen; Ozone; Polymer-flooding produced water; Polymers; Water Purification - methods; Cathode membrane; Polymer-flooding produced water; Membrane fouling; In situ self-cleaning
• ISSN: 0043-1354; 1879-2448
• DOI: 10.1016/j.watres.2023.119749

•A novel CM-E-HOC was firstly put forward to apply in produced water treatment.•The CM-E-HOC showed higher removal efficiency than the CM-EC processes.•Both reversible and irreversible membrane fouling were mitigated in the CM-E-HOC.•Alternating filtration in the CM-E-HOC can realize higher water production rate.•Excellent flux recovery can be achieved in the CM-E-HOC via in situ self-cleaning. Polymer-flooding produced water is more difficult to treat for reinjection compared with normal produced water because of the presence of residual hydrolyzed polyacrylamide (HPAM). A novel cathode membrane integrated electro-hybrid ozonation-coagulation (CM-E-HOC) process was proposed for the treatment of polymer-flooding produced water. This process achieved in situ self-cleaning by generated microbubbles in the cathode membrane. The CM-E-HOC process achieved a higher suspended solid (SS), turbidity and PAM removal efficiency than the CM-EC process. The SS in the CM-E-HOC effluent was ≤ 20 mg/L SS, which met the reinjection requirements of Longdong, Changqing Oilfield, China (Q/SYCQ 08,011–2019) at different current densities (3, 5 and 10 mA/cm2). The CM-E-HOC process greatly mitigated both reversible and irreversible membrane fouling. Therefore, excellent flux recovery was obtained at different in situ self-cleaning intervals during the CM-E-HOC process. Furthermore, alternating filtration achieved continuous water production during the CM-E-HOC process. On one hand, the effective removal of aromatic protein-like substances and an increase in oxygen-containing functional groups were achieved due to the enhanced oxidation ability of the CM-E-HOC process, which decreased membrane fouling. On the other hand, the CM-E-HOC process showed improved coagulation performance because of the increased oxygen-containing functional groups and polymeric Fe species. Therefore, larger flocs with higher fractal dimensions were generated, and a looser and more porous cake layer was formed on the membrane surface during the CM-E-HOC process. Consequently, the CM-E-HOC process exhibited better in situ self-cleaning performance and lower filtration resistance than the CM-EC process. [Display omitted]