The goal of this research is to elucidate virus control mechanisms during iron electrocoagulation (Fe-EC) at different pH values. The poster will show results from Fe-EC experiments wherein an iron anode and a stainless steel cathode were used and iron was dissolved by applying a voltage. Fe-EC was performed at pH 6.4 and 8.2 with different Fe dosages. In order to investigate inactivation of MS2, infective MS2 in floc was recovered using beef extract solution and assayed using plaque counting method. Figure 1 A and B shows that infective MS2 captured in floc decreased over time at pH 6.4 whereas negligible inactivation was observed at pH 8.2 regardless of iron dosage. At pH 6.4, the MS2 bacteriophage was predominantly controlled by sweep flocculation by amorphous iron (hydr)oxides. Inactivation by Fe(II), hydrogen peroxide, and free chlorine also contributed to inactivation at low pH. However, at pH 8.2, MS2 inactivation was insignificant. Relative amounts of Fe3+ and Fe2+, hydrogen peroxide, and free chlorine generation were also measured. Fe2+ was found to remain at a higher concentration during a longer period at pH 6.4 compared to pH 8.2. H2O2 generation solely due to Fe-EC was measured using the colorimetric Cu-DMP method. By adding 1,10-phenanthroline, it was possible to inhibit H2O2 generation due to serial reactions triggered by Fe2+ oxidation by dissolved O2 and, consumption of H2O2 by Fe2+ and Fe3+. As seen in Figure 2B, more H2O2 was generated at lower pH. Colorimetric measurements of free chlorine at two different pH also revealed that at the end of electrolysis, 0.052 mg/L and 0.021 mg/L of free chlorine was produced at pH 6.4 and 8.2, respectively. In addition to the results presented above, particle/floc characteristics such as zeta potential and size distribution will be analyzed for MS2 and iron floc to investigate interactions of particles during Fe-EC.

Relative importance of sweep coagulation and inactivation for virus control at different pH values during iron electrocoagulation

255th National Meeting (2018)

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