The moringa tree, widely known as the “miracle tree” or “tree of life” is celebrated for its nutritional density and traditional healing uses. Now, new research highlights another benefit: its seeds can efficiently filter microplastics from drinking water.
A study led by researchers at São Paulo State University in Brazil in collaboration with UK scientists demonstrates that a saline extract from moringa oleifera seeds (MOS-SE) acts as a powerful natural coagulant, removing up to 98.5 percent of polyvinyl chloride (PVC) microplastics from tap water.
The findings, published in the American Chemical Society’s ACS Omega journal, position moringa as a sustainable alternative to conventional chemical treatments. Moringa has been used for water purification for millennia. Ancient Greeks, Romans and Egyptians relied on it, noted study author Adriano Gonçalves dos Reis, a professor at the Institute of Science and Technology of São Paulo State University. His team has studied the tree’s seeds for more than a decade, focusing on their coagulant properties — the ability to make tiny particles clump together for easier removal. With rising concerns about microplastic pollution, they tested the seeds specifically against these contaminants.
PVC microplastics are particularly concerning due to their prevalence and potential toxicity in drinking water. In the study, researchers used aged PVC microplastics with an average size of 18.8 micrometers — roughly a quarter the thickness of a human hair. They tested the moringa seed extract in real tap water conditions using both direct filtration — coagulation, flocculation and filtration — and simplified in-line filtration systems that skip the flocculation step.
Under optimized in-line filtration at pH 6.0, 30 milligrams per liter (mg/L) of MOS-SE achieved a 99.4 percent reduction in turbidity, comparable to 98.6 percent with 9 mg/L of aluminum sulfate (alum). Scanning electron microscopy (SEM) confirmed microplastic removal reached 98.5 percent with moringa extract and 98.7 percent with alum. The SEM images showed complete removal of particles larger than 15 micrometers, with turbidity measurements proving to be a reliable proxy for microplastic removal performance. There was no statistically significant difference in efficiency between systems with and without flocculation. While flocculation increased aggregate sizes by about 41 percent — from 43.5 μm to 61.4 μm for MOS-SE — the larger flocs did not improve overall removal. This suggests that the flocculation step may be unnecessary for low-turbidity water, potentially simplifying treatment processes and reducing costs at drinking water facilities.
Moringa extract also outperformed alum across a wider pH range. Compared to alum, moringa seeds offer significant environmental benefits. They are renewable, biodegradable and produce far less sludge. The plant-based solution is also associated with fewer health risks.
One seed can treat approximately 10 liters of water, making the method promising for small communities or areas with limited access to chemical coagulants. However, scaling large urban treatment plants would require substantial quantities of seeds. A key tradeoff is the increase in dissolved organic carbon (DOC) from residual compounds in the seed extract. While higher MOS-SE dosages raised DOC levels, they also reduced specific ultraviolet absorbance by 88 percent at 30 mg/L or more, indicating effective removal of harmful hydrophobic organic matter linked to disinfection byproducts. Additional research is needed to assess long-term degradation of the extract, the fate of captured microplastics, cost-effectiveness at scale, and performance against other microplastic types and nanoplastics, the smallest particles most likely to enter human tissues.
The original research was done and report written by Gabrielle S. Batista, Victoria A. S. Ferreira, Luiz G. R. Godoy, Rodrigo B. Moruzzi, Soroosh Sharifi, and Adriano G. dos Reis.
To read the entire report visit: https://pubs.acs.org/doi/10.1021/acsomega.5c11569?fig=abs1&ref=pdf
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