The overall goal of this research is to evaluate mechanisms of virus control by iron electrocoagulation. The presentation will summarize results from a series of electrochemical coagulation (EC) experiments wherein an elemental iron anode was dissolved by applying a voltage to add coagulant in situ to destabilize viruses. Amorphous iron (hydr)oxides were formed that sweep flocculated the MS2 bacteriophage. Evidence is also shown for simultaneous MS2 inactivation caused by Fe(II) and intermediates such as free chlorine and hydrogen peroxide. Fe-EC was performed at 2.8 mA/cm2 and pH 6.4 with different Fe dosages. Infective virus concentration not only decreased in bulk phase, but also in flocs (Figure 1A), which indicates that MS2 is inactivated during Fe-EC. In order to investigate inactivation pathway, chemical coagulation using FeCl2 and FeCl3 was performed and compared to Fe-EC. As can be seen in Figure 1B, Fe(III) chemical coagulation did not inactivate MS2 present in flocs whereas approximately 3-log inactivation was achieved using FeCl2. Importantly, electrochemical iron addition inactivated viruses to a greater extent than chemical FeCl2 addition. Colorimetric measurements revealed that both free chlorine and hydrogen peroxide are produced during electrolysis (Figure 2A). In our experiments, at the end of electrolysis, 0.052 mg/L of free chlorine and 14 mg/L of H2O2 was measured. Since Fe2+ survives during the process, inactivation of MS2 by Fenton reaction triggered by Fe2+ and H2O2 can also be expected. Their roles in inactivation were confirmed by addition of scavengers (Figure 2B). The addition of sodium thiosulfate as free chlorine scavenger and sodium sulfite as H2O2 scavenger decreased MS2 inactivation in flocs. In addition to operational parameters, transformations of the MS2 capsid are being investigated using FTIR spectroscopy. Modifications to the RNA are also being pursued using RT-qPCR.

Simultaneous coagulation and inactivation during iron electrochemical treatment for virus control

255th National Meeting (2018)

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