Disinfection performance and mechanism of the carbon fiber-based flow-through electrode system (FES) towards Gram-negative and Gram-positive bacteria

• Published in: Electrochimica acta 2020-05, Vol.341, p.135993, Article 135993
• Main Authors: Ni, Xin-Ye, Liu, Hai, Xin, Lei, Xu, Zi-Bin, Wang, Yun-Hong, Peng, Lu, Chen, Zhuo, Wu, Yin-Hu, Hu, Hong-Ying
• Format: Article
• Language: English
• Subjects: Activation; Anodizing; Bacteria; Carbon fiber felt; Carbon fibers; Cell membranes; Chlorine; Coliforms; Deactivation; Disinfection; E coli; Electrochemical disinfection; Electrodes; Gram-negative bacteria; Gram-positive bacteria; Oxidation
• ISSN: 0013-4686; 1873-3859
• DOI: 10.1016/j.electacta.2020.135993

The disinfection performance of a carbon fiber-based flow-through electrode system (FES) towards Gram-negative bacteria (Escherichia coli and fecal coliform) and Gram-positive bacteria (Enterococcus faecalis and Bacillus subtilis) in normal saline was systematically investigated over a wide range of applied voltages (1–5 V) and hydraulic retention times (HRTs) (1–10 s). It was revealed that the Gram-negative bacteria were more vulnerable to FES for their thinner cell walls, and over 6.5 log removal (no live bacteria detected) was achieved at the applied voltage of 2 V and HRT of 2 s; while Gram-positive bacteria were inactivated at slightly higher voltages (3 V, 2 s) or longer HRTs (2 V, 5 s). Bacterial inactivation was attributed to the change and rupture of cell membrane mainly by anode direct oxidation without bacterial regrowth/reactivation. In addition, negligible generation of the free chlorine at low voltages (≤2 V) can avoid the formation of potential chlorinated disinfection byproducts (DBPs). Hence, FES can offer a potential alternative to conventional disinfection methods for bacterial inactivation in natural and contaminated water. [Display omitted] •Flow-through electrode system (FES) inactivated various bacteria below 3 V.•Carbon fiber felt (CFF) anode dominated the disinfection process.•The inactivation was attributed to the rupture of cell membrane.•Gram-negative bacteria were more vulnerable to FES than Gram-positive bacteria.