(512a) Enhanced Virus Removal in a Practical Sand Filter

The lack of clean drinking water is a critical issue across the world, as 844 million people still lack sufficient access to clean drinking water. Previous studies revealed that simple functionalization of sand (f-sand) filters, using a water extract of Moringa oleifera (MO) seeds, results in >8 log₁₀ removal of E. coli. However, many disease outbreaks from contaminated drinking water are caused by viruses, which are relatively more difficult to detect and remove from water. The purpose of this presentation is to report an unprecedented, high virus removal observed in a practical sand filter. We found that f-sand filters, using a water extract of Moringa oleifera (MO) seeds, can enable ~7 log₁₀ (or 99.99999%) removal efficiency of MS2 bacteriophage, a surrogate for human enteric viruses. However, a surprising discovery from experiments was that the origin of MO seeds used to prepare f-sand filters critically affect virus removal. This observation led us to probe the composition of proteins adsorbed on ­f-sand to identify the source of virus removal activity. A combination of gel electrophoresis and mass spectrometry indicated the presence of two proteins (MoCBP and MO2.1) adsorbed on f-sand. Molecular docking simulations of these proteins with the MS2 capsid protein suggested that favorable interactions between MoCBP and MS2 drives the virus removal. MoCBP is known to exhibit antifungal and chitin binding activity. Our simulations indicated that chitin monomers and MS2 interact with MoCBP through similar binding regions. Further column experiments guided by simulations revealed that the specific interactions of MS2 capsid with the chitin-binding region of MoCBP is the molecular mechanism of removal in f-sand filters. We propose f­-sand filters as a highly effective, energy-efficient, and practical technology for virus removal applicable to both developing and developed countries.