A new study suggests that extracts made from moringa seeds can help remove microplastics from water, and in some conditions may work as well as, or even better than, a chemical already widely used in treatment plants.

The research was carried out at the Institute of Science and Technology of São Paulo State University (ICT-UNESP).

The study focused on Moringa oleifera, a plant native to India that grows well across many tropical regions and has long attracted interest for its possible use in water treatment.

A plant with promise

Moringa is often praised for its edible leaves and seeds, which are rich in nutrients. But scientists have also spent years looking at whether those same seeds could play a useful role in cleaning water.

This new study adds to that idea by testing whether moringa seed extract can help remove microplastics.

That question matters because microplastics are now being found almost everywhere, including rivers, lakes, and even treated drinking water.

The researchers found that the saline extract from moringa seeds performed in a way that closely matched aluminum sulfate, one of the standard coagulants used in water treatment. In more alkaline water, moringa actually did even better.

A simpler method for treating water

Study lead author Gabrielle Batista conducted the research as part of her master’s degree in environmental engineering at UNESP.

“We showed that the saline extract from the seeds performs similarly to aluminum sulfate, which is used in treatment plants to coagulate water containing microplastics. In more alkaline waters, it performed even better than the chemical product,” said Batista.

That result is especially interesting because aluminum sulfate is already a familiar tool in water treatment.

If a plant-based alternative can do comparable work, it opens the door to a treatment method that may be simpler and potentially more sustainable in some settings.

How the process works

The study focused on a treatment method known as in-line filtration. This is generally used for water with low turbidity, meaning water that is relatively clear and does not need as many preliminary treatment steps.

In this process, water first goes through coagulation. That step is crucial because pollutants such as microplastics usually carry a negative electrical charge on their surface, which means they repel one another and also resist sticking to the sand used in filters.

A coagulant changes that, neutralizing the charge, and allowing the particles to clump together into larger masses that can be trapped more easily in a filter.

In this case, the researchers tested two coagulants: the moringa salt extract and aluminum sulfate.

The moringa extract has one practical advantage too. It can be prepared in a fairly simple way, which makes it especially interesting for places that may not have access to more complex treatment systems.

“The only drawback found so far regarding aluminum sulfate was the increase in dissolved organic matter, the removal of which could make the process more expensive,” said study coordinator Adriano Gonçalves dos Reis, a professor at ICT-UNESP.

“However, on a small scale, such as on rural properties and in small communities, the method could be used cost-effectively and efficiently.” 

Why PVC was tested

To test the method, the researchers started with tap water and deliberately contaminated it with polyvinyl chloride, better known as PVC. They chose PVC for a reason.

Among common plastics, PVC is considered especially worrying for human health because of its documented mutagenic and carcinogenic potential. It is also widely found on the surface of water bodies and in water that has already gone through conventional treatment.

The team artificially aged the PVC with ultraviolet radiation so that it would behave more like microplastics found in the real world, which have usually already been altered by sunlight and environmental exposure.

That water was then treated using coagulation and sand filtration in a Jar Test device, which allows researchers to simulate water treatment on a small scale. They then compared the results from the moringa treatment with the results obtained using aluminum sulfate.

To see how effective the treatment had been, the team used scanning electron microscopy to count the microplastic particles before and after treatment.

The researchers also measured the size of the flocs, the clumps formed during coagulation, using a high-speed camera and a laser beam.

In the end, the different treatments did not show significant differences in particle removal. That suggests the moringa-based method can stand up fairly well against the conventional chemical option.

The search for sustainable methods

The work also builds on earlier research by the same group. In a previous study, they had already shown that moringa seeds could be effective in a full water treatment cycle involving coagulation, flocculation, sedimentation, and filtration.

This newer study narrows the focus to in-line filtration, which is a simpler system and therefore potentially more practical in certain real-world situations. That makes the findings feel more usable.

The group is now testing moringa seed extract on water collected directly from the Paraíba do Sul River, which supplies São José dos Campos. So far, according to the researchers, the product has also shown strong performance in treating natural water.

That next step is important because river water is much more complex than laboratory-prepared samples. If moringa continues to perform well there, the case for its use becomes much stronger.

“There’s increasing regulatory scrutiny and health concerns regarding the use of aluminum- and iron-based coagulants, as they aren’t biodegradable, leave residual toxicity, and pose a risk of disease. For that reason, the search for sustainable alternatives has intensified,” Reis explained.

Nature offers new solutions

What makes this study stand out is how practical the idea feels. Moringa is already familiar in many tropical countries. Its seeds are widely available, and the extract used in the study is relatively simple to prepare.

That does not mean it is ready to replace standard treatment everywhere. Large-scale systems have their own technical demands, and the researchers themselves note that there are still factors to consider, such as dissolved organic matter.

Still, the results point to something promising. A natural material that is already accessible in many parts of the world may be able to help remove microplastics from water in an efficient way.

At a time when microplastic pollution feels almost impossibly widespread, that kind of finding matters. 

It suggests that some solutions may not need to come from entirely new inventions. Sometimes they may come from looking again at a plant that has been around all along.

The research is published in the journal ACS Omega.

NOTE – This article was originally published in Earth and can be viewed here