Moringa seed is a proven coagulant, but its use in filters has been limited by low removal efficiency and leftover organic matter. This study, published in an ACS Environmental Science & Technology Letters, engineered a better moringa sand filter.
Researchers used Moringa oleifera seed extract — rich in cationic antimicrobial proteins — to reverse the surface charge of sand (creating “f-sand”) to +10 mV at a dose of 5.6 g of seeds per m² of sand.
Key findings
- The f-sand filter achieved 4-log removal of 1 µm particles.
- It achieved more than 8-log removal of E. coli, versus less than 0.1-log for untreated sand.
- The dramatic improvement came from attractive electrostatic interactions between the charged sand and contaminants.
Caveat: a laboratory filter-design study; field filters require validation at scale.
Summary of: (2017). “Moringa f-sand Filters for Sustainable Water Purification.” Environmental Science & Technology Letters. DOI: 10.1021/acs.estlett.7b00490. Summarised by MORIFA; full paper (subscription) via the link above.