Moringa oleifera coated sand filters: virus removal and scale-up
Open Access
- Author:
- Pei, Andrew
- Area of Honors:
- Chemical Engineering
- Degree:
- Bachelor of Science
- Document Type:
- Thesis
- Thesis Supervisors:
- Stephanie Butler Velegol, Thesis Supervisor
Andrew Zydney, Thesis Honors Advisor - Keywords:
- Virus filtration
clean water
sustainability
scale-up
Moringa oleifera
water purification
f-sand
MS2
molecular docking - Abstract:
- The clean water crisis affects roughly 1 in 9 people worldwide. An absence of clean water leads to widespread deadly waterborne disease, which kills some 842,000 people each year. Point-of-use technology that can be directly applied to purify surface water, such as membranes, chlorination, ceramic filters, and boiling have demonstrated the ability to significantly decreases the rate of diarrheal disease. The Moringa oleifera (MO) tree is a tropical tree native to India, whose seeds contain cationic antimicrobial proteins. These cationic proteins will electrostatically adsorb to anionic surfaces such as silica sand, creating functionalized sand, or f-sand. When packed into a column, f-sand filters demonstrated high removal of E. coli and model microbes, making it a potential addition to the list of point-of-use water treatment technology. However, viruses are a large contributor to waterborne disease and are much harder to remove than bacteria due to their size. In this study, the purification capabilities of the f-sand filter are further explored by testing the removal of MS2 bacteriophage, a model virus. Using 106-micron glass beads and a flow rate of 1.6 mL/min, the f-sand filter was able to remove >7-log10 (99.99999%) MS2, which is abnormally high for a sand filter. Further experiments revealed the mechanism for virus removal by a binding pocket within a chitin binding protein found in Moringa seed extract. Additionally, the first ever field scale-up of the Moringa filter was performed in Fort Myers, Florida. Two filters were built using PVC, bamboo, and locally available sand and Moringa seeds. Moringa filters demonstrated superior improvement of the visual clarity of water, as well as >99.9% removal of total coliform. These scale-up experiments also shed light on significant challenges towards implementing the filter in a practical manner, which includes minimizing the amount of water necessary to construct the filter, extending the filter lifetime, optimizing flow rate, and finding small enough sand.