The purpose of this paper is to report an unprecedented, high virus removal observed in a practical sand filter and the corresponding mechanism of removal. Fecal contamination of drinking water and related health burden is a global challenge. Among the pathogens present in contaminated water, viruses are especially difficult to detect and treat leading to frequent outbreaks worldwide. No definitive solution exists for this problem due to the limitations with the current technologies. Disinfection is effective but can be prone to failure as currently practiced while boiling is considered a last resort intervention. We found that simple functionalization of sand (f-sand) filters, using a water extract of Moringa oleifera (MO) seeds, can enable ~7 log10 virus removal efficiency. These tests were conducted with MS2 bacteriophage, a surrogate for human enteric viruses. A surprising discovery from experiments was that the origin of MO seeds used to prepare f-sand filters critically affect the virus removal. This 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 virus (MS2) capsid proteins 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. The removal mechanism based on specific molecular interactions between virus capsid and plant-based protein provides a molecular basis for screening and engineering plant-based proteins to filter viruses in water, medicine and agricultural applications.

Enhanced virus removal in a practical sand filter

2019 Fall National Meeting

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