In the new study, the team, including a group of Penn State undergraduates led by graduate student Boya Xiong, packed the sticky sand into filter columns about 1 cm in diameter and 5-10 cm high, and testing the columns with extract from different amounts of seed to optimize performance. In experiments with 1-µm-diameter polystyrene particles, which have about the same size and charge as bacteria, they found that the sticky sand caught 99.99% of particles, compared with 13.55% for sand alone. The sticky sand also removed 108 viable E. coli cells per milliliter. They estimate that a household-scale filter 1 meter tall and 5 cm in diameter that provides 10 L of water per day would require 0.2 kg of seeds per year, whereas a Moringa tree produces about 480 kg of seeds per year.
Tropical tree seeds provide sustainable water filtration | Chemical & Engineering News