Efficient Removal of Escherichia coli from Ballast Water Using a Combined High-Gradient Magnetic Separation-Ultraviolet Photocatalysis (HGMS-UV/TiO2) System
2018
Lu, Zheng | Zhang, Kun | Shi, Yue | Huang, Yanli | Wang, Xixi
A new synergistic method was proposed to remove Escherichia coli by using high-gradient magnetic separation (HGMS)-ultraviolet titanium oxide photocatalysis (UV/TiO₂). Compared with sole HGMS, UV radiation, UV/TiO₂, and HGMS-UV, the combined HGMS-UV/TiO₂ significantly increased the bacterial removal rate. After treatment of 6 min, bacterial removal rate for HGMS-UV/TiO₂ was 5.25 log, and E. coli was unlikely to photoreactivate or dark repair. In addition, HGMS-UV/TiO₂ treatment led to rapid increase of malondialdehyde (MDA) concentration, severe inhibition of superoxide dismutase (SOD) activity, and massive leakages of intracellular K+ and protein, proving the process caused more damage to E. coli cell structure. For HGMS-UV/TiO₂ treatment, seawater turbidity did not significantly affect the bacterial removal rate, and 10 mg L⁻¹ humic acid could largely reduce the bacterial removal rate. Totally, the HGMS-UV/TiO₂ could be effectively employed to treat ballast water with less organic matter. Despite the limitation, this novel method has many potential applications in the treatment of ballast water.
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