(146a) Mechanisms of Improvements in Virus Control By Electrocoagulation: Removal and Inactivation

Prof. Baltus and I have collaborated for over a decade on microorganism control from contaminated water supplies. We have coauthored papers on (hindered) convection and diffusion of bacteria and virus across microporous filters, but my group has been separately pursuing the idea of virus aggregation. The principal hypothesis from an environmental engineering standpoint is that virus removal is facilitated by increasing effective size using large-pored microfilters, which otherwise do not remove them. An additional advantage of coagulation is that it simultaneously removes other contaminants including natural organic matter and colloids thereby improving overall quality of our drinking water. My presentation will cover aspects of virus aggregation by externally added hydrolyzing metal-ion coagulants.

The principal objectives of this research are to elucidate underlying virus destabilization/removal mechanisms during electrocoagulation and identify possible intermediates leading to inactivation. We explore the electrochemical oxidation of sacrificial elemental aluminum and iron anodes to directly dissolve metal ion coagulant precursors that neutralize virus surface charge and upon hydrolysis sweep coagulate viruses. In all cases, the F-specific ssRNA coliphage MS2 was employed as the model virus. Atomic force microscopy was performed to directly measure adhesion forces between viruses and aluminum precipitates. Experiments were performed on synthetic buffered water at low and high pH as well as using saline background solutions to electrolytically produce free chlorine. Low chlorine concentrations combined with virus shielding and aggregation within flocs resulted in very slow disinfection rates in solutions with high salinity.

Inactivation mechanisms were pursued via attenuated total reflectance – Fourier transform infrared spectroscopy and quantitative reverse transcription polymerase chain reaction. Evidence for oxidative transformations of capsid proteins including formation of oxyacids, aldehydes, and ketones and RNA damage kinetics will be discussed. Finally, recent results on electrochemical iron inactivation and coagulation will be presented.