Simple wood dust filter removes 99 per cent of microplastics from water solution

Researchers at the University of British Columbia (UBC) have found that adding natural plant compounds, known as tannins, to a layer of wood dust creates a filter that traps virtually all microplastic particles present in water.

Microplastics are tiny pieces of plastic debris resulting from the breakdown of consumer products and industrial waste, and keeping them out of water supplies is a huge challenge.

They are typically present in both tap water and bottled water. US studies have shown that an average of 325 plastic particles can be found in a litre of bottled water, and around 5.5 plastic particles per litre of tap water. Their long-term health impact on the human body is still largely understood.

While the experiment is confined to the laboratory at this stage, the team says this bioCap solution can be scaled up relatively easily and inexpensively.

UBC’s Dr Orlando Rojas said: “Our filter, unlike plastic filters, does not contribute to further pollution as it uses renewable and biodegradable materials: tannic acids from plants, bark, wood and leaves, and wood sawdust – a forestry by-product that is both widely available and renewable.”

The team analysed microparticles released from popular tea bags made of polypropylene.

They found that their method trapped between 95.2 and 99.9 per cent of plastic particles in a column of water, depending on plastic type. When tested in mouse models, the process prevented the accumulation of microplastics in the organs.

“There are microfibres from clothing, microbeads from cleansers and soaps, and foams and pellets from utensils, containers and packaging,” Rojas added. “By taking advantage of the different molecular interactions around tannic acids, our bioCap solution was able to remove virtually all of these different microplastic types.”

Another recent study showed that microplastics are also airborne, with humans breathing in up to a credit card’s worth every week.