Viral contamination of drinking water due to fecal contamination is difficult to detect and treat effectively, leading to frequent outbreaks worldwide. The purpose of this paper is to report on the molecular mechanism for unprecedented high virus removal from a practical sand filter. Sand filters functionalized using a water extract of Moringa oleifera (MO) seeds, functionalized sand (f-sand) filters, achieved a ∼7 log10 virus removal. These tests were conducted with MS2 bacteriophage, a recognized surrogate for pathogenic norovirus and rotavirus. We studied the molecular mechanism of this high removal since it can have important implications for sand filtration, the most common water treatment technology worldwide. Our data reveal that the virus removal activity of f-sand is due to the presence of a chitin-binding protein, M. oleifera chitin-binding protein (MoCBP) on f-sand. Standard column experiments were supported by proteomic analysis and molecular docking simulations. Our simulations show that MoCBP binds preferentially to MS2 capsid proteins demonstrating that specific molecular interactions are responsible for enhanced virus removal. In addition, we simplified the process of making f-sand and evinced how it could be regenerated using saline water. At present, no definitive solution exists for the challenge of treating fecally contaminated drinking and irrigation water for viruses without using technologies that demand high energy or chemical consumption. We propose functionalized sand (f-sand) filters as a highly effective, energy-efficient, and practical technology for virus removal applicable to both developing and developed countries.
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The authors would like to thank Andrew Erdman for providing Moringa seeds. The authors acknowledge Dr. Tatiana Laremore for help with sample preparation for and data interpretation of mass spectrometric analysis. The authors would like to thank Prof. B. Tracy Nixon for helpful discussions about affinity column chromatography. The authors would like to thank Dr. Tammy Wood for providing the fluorescent E. coli strain. This work was supported, in part, by funding from the National Science Foundation project (CBET-1705278). Additional funding support was provided by the Department of Chemical Engineering at Pennsylvania State, a National Science Foundation REU program (EEC-1659497) and Pennsylvania State University Global Programs.
© 2019 American Chemical Society.