Study On Inactivation Of Bacteria By Filtered Carbon Fiber Electrode

Disinfection is an important process to ensure water quality and safety.Electrochemical disinfection technology has attracted much attention due to its advantages of environmental friendliness,safety and high efficiency.However,the effective disinfection area of the existing electrochemical disinfection technology is only limited on the electrode surface,which has the disadvantages of low disinfection efficiency and high power consumption.The purposes of this study is to set up a new electrochemical disinfection filter from different carbon fiber felts,and to choose the best candidate via evaluating their potentials as electrodes for disinfection.Then the disinfection mechanisms and suitable working conditions of the device were investigated to provide reliable technical support for its application.Physical,chemical,and disinfection properties of the four kinds of carbon fiber felts were investigated systematically,namely PCF,A-PCF,A-LCF and A-PUF(origin PAN-based carbon fiber felt(PCF),activated PAN-based carbon fiber felt(A-PCF),plant fiber based activated carbon fiber mat(A-LCF)and polyurethane foam-based activated carbon fiber find(A-PUF)).Among them,PCF and A-PCF had the highest conductivity,and A-PCF and CNT got the largest degree of graphitization.The disinfection results indicated that the four kinds of carbon felts can be promising electrodes for electrochemical disinfection,and A-PCF showed the best performance,which achieved>6.5-log removal of E.coil bacteria at a cell potential of 2 V and a hydraulic residence time of 2 s.The disinfection effect of A-PCF on Gram-negative bacteria(E.coil and Fecal coliform)and Gram-positive bacteria(Enterococcus faecalis and Bacillus subtilis)was investigated.The results showed that the A-PCF electrode had a good universality,which achieved>6.0-log removal of all four bacteria at a cell potential of 2 V.In this study,using E.coili as model microorganism,the resurgence risk of E.coili and stability of A-PCF electrode after disinfection were investigated.The results showed that the concentration of E.coili decreased with the increase of storage time,and A-PCF showed good bacterial removal efficiency within 1 h.Using E.coili as the typical research object,the disinfection mechanisms and optimum disinfection conditions of A-PCF electrode were investigated,and the results showed that at the cell potential below 2 V,chlorine in the effluent was undetectable,and solution pH was independent,the impact of disinfection by-products could be excluded.When the applied voltage was 2 V,the cell membrane of E.coli showed obvious damage,indicating that the direct effect of electric field caused bacterial inactivation.This study suggested that at cell potential of 2 V the A-PCF electrode can achieve safe,efficient and stable disinfection.