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Moringa oleifera f-sand Filters for Sustainable Water Purification
journal contribution
posted on 2017-11-22, 00:00 authored by Boya Xiong, Bethany Piechowicz, Ziyuhan Wang, Rose Marinaro, Emma Clement, Taylor Carlin, Adam Uliana, Manish Kumar, Stephanie Butler VelegolThe purpose of this work is to determine
parameters for the design
of a Moringa seed sand filter for water purification. Moringa oleifera seeds containing cationic antimicrobial
proteins have been used as natural coagulants for the removal of turbidity;
however, a low removal efficiency and high residual organic levels
limit their applications. In this work, Moringa seed
extracts were used to reverse the charge of sand (f-sand) to 10 mV at a seed dosage of 5.6 g of seeds/m2 of
sand. This f-sand filter demonstrated ∼4 log
removal of 1 μm polystyrene particles and >8 log removal
of Escherichia coli compared to <0.1 log removal
for bare
sand. Enhanced removal for particles and E. coli was
dominated by attractive electrostatic interactions. Clean bed filtration
modeling predicts a sticking coefficient (α) of 0.8 for f-sand compared to a value of 0.01 for bare sand. This α
was further validated under a wide range of filtration conditions.
Preliminary scale-up analyses suggest a point-of-use f-sand filter that requires a very small amount of seeds annually.
The outcome of this work presents the scientific basis for the design
of a water purification solution for developing regions, requiring
only locally available resources and no use of synthetic chemicals
or electricity.