The filter that fits in your palm could help clean our oceans — Arash Rasti and Khor Sook Mei

JUNE 27 — If you scoop a bucket of seawater from almost any coastline today, you will collect more than salt and sand. 

Hidden within it are tiny fragments of plastic, some so small they cannot be seen with the naked eye. 

These microplastics have become one of the defining environmental challenges of our time, travelling through rivers, oceans and marine food chains before eventually finding their way back to us.

Unlike larger pieces of plastic waste, microplastics are remarkably difficult to remove. 

Their tiny size allows them to remain suspended in water, making conventional filtration systems less effective or requiring increasingly complex treatment processes. 

Many existing technologies are also designed for large industrial facilities, limiting their suitability for situations where compact, portable or affordable filtration systems are needed.

Sometimes, however, solving a large environmental problem begins with asking a surprisingly simple question. Can we make the filter smaller instead of making the system bigger?

That question became the starting point of our research at Universiti Malaya. Rather than designing another large filtration column, we developed a compact filtration disk measuring just 40 millimetres in diameter. 

The disk combines natural zeolite, a porous mineral widely recognised for its filtration properties, with polyvinyl alcohol (PVA), a polymer that helps strengthen the structure while allowing careful control of the membrane’s pore size. 

The objective was straightforward. Could such a compact device effectively retain microplastics while still allowing seawater to pass through at a practical rate?

The answer, encouragingly, was yes. Laboratory testing demonstrated that the composite disks successfully retained microplastics made from three of the world’s most common plastics: polyethylene terephthalate (PET), polyethylene (PE) and polypropylene (PP). 

Even particles as small as 0.22 micrometres showed no detectable breakthrough under the experimental conditions. 

At the same time, the disks maintained water flow rates that compared favourably with much larger filtration systems, showing that compactness need not come at the expense of performance.

Achieving both effective filtration and practical water throughput is often one of the biggest engineering challenges in membrane design. 

Pores that are too large allow contaminants to escape. Pores that are too small restrict water flow and quickly become clogged. Finding the right balance is rather like designing a highway. 

Too many lanes make traffic flow smoothly but allow unwanted vehicles through. Too few lanes create bottlenecks. Successful filtration depends on getting that balance right.

Our work focused precisely on that balance. By carefully adjusting the amount of PVA coating, we were able to control the membrane’s surface structure and pore size. 

Lower PVA concentrations allowed higher water flow, while higher concentrations improved particle retention. The resulting composite provided a practical compromise between filtration efficiency and permeability, two properties that are often difficult to optimise simultaneously.

Equally important was the choice of material itself. Natural zeolite is inexpensive, chemically stable and readily available in many parts of the world. 

Using naturally abundant materials offers advantages beyond laboratory performance. It opens opportunities for producing filtration devices that are affordable and potentially accessible to a much wider range of users. 

In environmental technologies, cost frequently determines whether an innovation remains confined to research laboratories or finds its way into practical use.

Of course, laboratory success is only the beginning. Real seawater is a far more complicated environment than controlled laboratory samples. 

It contains microorganisms, suspended sediments, dissolved organic matter and continuously changing physical conditions. 

While our study demonstrated promising performance under controlled seawater testing, much remains to be explored before such technology can be deployed at larger scales or for long-term operation. 

Questions relating to durability, continuous filtration and large-volume applications will require further investigation.

That is how science progresses. Each study answers one important question while revealing several new ones. Yet every technological advance begins with a proof of concept.

The world often imagines environmental innovation as something dramatic: enormous floating barriers, vast desalination plants or sophisticated industrial machinery. 

Those solutions certainly have their place. But sometimes the next meaningful step is much smaller. It may fit comfortably in the palm of your hand.

As concerns over marine pollution continue to grow, there is increasing need for filtration technologies that are not only effective, but also practical, scalable and affordable. 

Compact filtration systems may eventually support applications ranging from marine environmental monitoring and aquaculture to emergency water treatment and portable research equipment. 

Whether they ultimately serve these roles will depend on continued engineering development and field validation, but the possibility is now clearer than before.

The oceans do not need a single miracle technology. They need thousands of practical solutions working together, each solving one small part of a much larger problem. Sometimes, one of those solutions begins with a filter no bigger than your palm.

* Arash Rasti and Associate Professor Dr Khor Sook Mei are from the Department of Chemistry, Faculty of Science, Universiti Malaya. The authors may be contacted at naomikhor@um.edu.my 

** This is the personal opinion of the writer or publication and does not necessarily represent the views of Malay Mail.