Effects of magnetotactic bacteria (MTB) on membrane fouling control in an ultrafiltration treatment of chromium-containing surface water

Ultrafiltration membranes are widely used in the treatment of surface water. However, membrane fouling is a core issue that needs to be addressed in its application. Magnetotactic bacteria (MTB) show early film-forming and magnetotactic behaviour in the presence of external magnetic fields. The objective of this study was to alleviate membrane fouling in ultrafiltration membranes using MTB, which can prioritise film formation and show directional movement under external magnetic fields. The concentration of Cr⁶⁺ in the water was 10 mg/L, and the dosage of MTB was 10 mg/L. Results show that the transmembrane pressure of the ultrafiltration membrane decreased by 5 kPa following the application of a magnetic field of 33.71 mT for a period of 90 min, and the membrane fouling could therefore be effectively controlled. With the addition of MTB, the average removal of Cr⁶⁺ from water by the ultrafiltration system was 20.10%, which was 14.56% higher than that of the conventional ultrafiltration system. The average removal of chromaticity was 20.13%, which was 10% higher than that achieved by the conventional ultrafiltration system. Furthermore, MTB progressively developed into the predominant flora during the operational phase, thereby enhancing the efficiency of the ultrafiltration system.