Could Moringa oleifera seeds help remove microplastics from water? The answer, for now, comes from a study published in ACS Omega: a saline extract obtained from moringa seeds removed 98.5% of the aged PVC microplastics present in low turbidity water, with a yield almost identical to that of aluminum sulphate, the chemical coagulant used in many treatment plants. In the comparative test, alum reached 98.7%. A minimal difference, within a controlled experiment, but strong enough to make us look at those seeds with less folklore and more attention.
Moringa, native to India and grown in many tropical countries, has long been used for its nutritious leaves, seeds, some traditional uses and even for honey production. In many rural communities, especially where water infrastructure is fragile or expensive, seeds have been studied for years as natural coagulants: they help particles dispersed in water to aggregate, making them easier to retain with filtration.
The mechanism, said without putting on a gown even when washing your hands would be enough, works like this: many particles present in the water, including microplastics, have a negative electrical charge on the surface. This charge makes them repel each other and keeps them suspended. Moringa extract neutralizes that repulsion, encourages the formation of larger clumps, and allows the sand filter to intercept them. The same principle guides the use of conventional coagulants in plants, only here the raw material comes from a seed.
The researchers chose PVC because it is among the most problematic plastics for health and the environment, also due to the possible release of additives and substances associated with toxic effects. Before testing, the particles were artificially “aged” with ultraviolet radiation, to mimic what happens when plastic is exposed to the environment and fragments. Then the contaminated water passed through a laboratory system that reproduces, in a small way, some phases of water treatment: coagulation, filtration and, in some tests, even flocculation.
Comparison with alum
The most interesting part of the study concerns the comparison with aluminum sulphate. Alum is a very widespread product in water treatment, effective and already integrated into existing infrastructures. Moringa, however, compared well and showed a more stable performance over a wider pH range, from 5.0 to 8.0, while alum performed better between 5.0 and 7.0. In more alkaline waters, therefore, the tropical seed has shown a practical advantage.
There is also an operational detail that matters. In tests, in-line filtration, i.e. the passage from coagulation directly to the filter, gave equivalent results to direct filtration with flocculation phase. Translated into system terms: one less step, at least in the conditions tested, could simplify the process. For small systems, villages, farms, isolated communities or contexts where chemical reagents cost too much, this difference can become anything but secondary.
Here you need to keep your feet on the ground. Moringa leaves more dissolved organic matter in the treated water, and that residue may require additional removal steps. In large urban aqueducts, where enormous volumes circulate every day, very large quantities of seeds and careful management of organic waste would be needed. The same research therefore indicates a more realistic space: small scale, rural communities, local systems, places where growing the plant is already part of the daily economy.
A problem that enters everywhere
Microplastics are tiny fragments, under 5 millimetres, sometimes visible to the naked eye, sometimes so small that they fall into the category of nanoplastics. They have been found in water, air, soil, deep oceans, foods and various human tissues. A study published in Nature Medicine in 2025 it detected micro- and nanoplastics in brain, liver and kidney samples, with associative data calling for caution and further verification of health effects.
Prudence matters, because science is still working on the consequences for human health. The presence is now documented, the biological risk must be better defined. The World Health Organization had already flagged the need for more data on the presence of microplastics in drinking water, measurement methods and possible health impacts. Even the famous estimate of the “credit card” ingested every week, released in 2019, was later criticized by other researchers for the margins of error and the difficulties in combining very different data.
The crudest fact remains: the plastic produced, used and dispersed continues to fragment. Some additives associated with plastics, such as bisphenols and phthalates, are studied for their ability to interfere with the endocrine system, i.e. with hormonal regulation. PVC, at the center of the study on moringa, is one of the materials observed with particular attention precisely because of its composition and the substances it can carry with it.
Where it can be useful
The value of moringa lies in its apparent simplicity. It grows in warm areas, produces seeds, can be grown alongside other food and agricultural uses, and requires less heavy technologies than many industrial solutions. For a large European aqueduct, there remains a path to study, to standardize, to verify on real waters and with rigorous protocols. For a small tropical community, however, it could become an accessible, local resource, less dependent on external chemical supplies.
The research group is already testing the extract on water collected from the Paraíba do Sul river, which feeds São José dos Campos, in the state of São Paulo. It is an important step, because real water brings with it organic substances, minerals, seasonal variations, turbidity and different contaminants. The laboratory serves to understand the mechanism. The river decides how long that mechanism holds out of the case.
Moringa seeds alone do not eradicate the microplastic problem. No filter resolves downstream what we continue to produce upstream. However, this study adds a useful piece: a plant known for centuries can enter, with a scientific method, into one of the dirtiest environmental issues of the present.
You might also be interested in:
