Fouling mitigation in an anaerobic membrane bioreactor via membrane surface modification with tannic acid and copper

• Published in: Environmental pollution (1987) 2021-12, Vol.291, p.118205-118205, Article 118205
• Main Authors: Maneewan, Punika, Sajomsang, Warayuth, Singto, Sudkanueng, Lohwacharin, Jenyuk, Suwannasilp, Benjaporn Boonchayaanant
• Format: Article
• Language: English
• Subjects: AnMBR; Hydrophilicity; Membrane fouling; PVDF; Ultrafiltration
• ISSN: 0269-7491; 1873-6424
• DOI: 10.1016/j.envpol.2021.118205

Anaerobic membrane bioreactors (AnMBRs) have recently received a great amount of attention as an alternative anaerobic treatment process due to their superior capability for sludge retention with high effluent quality. Nevertheless, membrane fouling in AnMBRs has been a major concern. In this study, the surfaces of polyvinylidene fluoride (PVDF) ultrafiltration membranes were modified with tannic acid (TA) and Cu(II) at various molar ratios of TA to Cu(II), including 3:1, 2:1, 1:1, 1:2, and 1:3. The hydrophilicity, morphology, chemical structure, elemental composition, and antibacterial properties of the unmodified and modified membranes were analyzed using water contact angle measurements, scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FT-IR), SEM-energy dispersive X-ray spectrometry (SEM-EDX), and the clear zone method, respectively. The modified membrane with a TA-to-Cu(II) molar ratio of 1:3 had high hydrophilicity with certain antibacterial properties; therefore, it was selected to be further tested in an AnMBR along with an unmodified membrane. The chemical oxygen demand (COD) removal efficiencies of the unmodified membrane and modified membrane were 92.2 ± 3.6% and 91.8 ± 4.0%, respectively. The modified membrane had higher permeability after backwashing with less chemical cleaning (CC) than the unmodified membrane. Surface modification with TA and Cu(II) appeared to reduce irreversible fouling on the membranes. •The surfaces of PVDF ultrafiltration membranes were modified with tannic acid and Cu(II).•Membrane hydrophilicity, morphology, chemical structure, elemental composition, and antibacterial properties were analyzed.•The modified membrane with a tannic acid-to-Cu(II) molar ratio of 1:3 was selected to be tested in an AnMBR.•The modified membrane had higher permeability after backwashing with less chemical cleaning than the unmodified membrane. The PVDF membrane modified with tannic acid and Cu(II) had higher permeability and required less cleaning in an AnMBR than unmodified membrane due to its antibiological fouling properties.