Researchers at Japan’s Shinshu University have developed a natural flocculant based on mucilage from nameko mushrooms (Pholiota nameko). The material efficiently removes microplastics and nanoplastics from water. The study shows how a readily available biological material could provide a more sustainable alternative to conventional chemical water treatment. It could also support future wastewater purification and environmental remediation.

A Natural Flocculant From Edible Mushrooms

Microplastics and nanoplastics increasingly contaminate rivers, lakes and oceans as larger plastic products break down over time. Scientists continue to investigate their effects on ecosystems and human health. At the same time, practical and safe removal methods remain limited.

The research team investigated whether the naturally slippery coating on edible nameko mushrooms could help solve this problem. The mushroom’s distinctive texture comes from a polysaccharide-rich mucilage that contains pectin. This naturally occurring compound binds particles together.

The researchers selected nameko mushrooms because they are inexpensive, widely available in Japan and non-toxic. These qualities make them a promising renewable resource for water treatment.

Rapid Removal Of Micro- And Nanoplastics

The team prepared the flocculant by immersing and gently shaking the mushrooms in water for five minutes. They then mixed the mucilage solution with iron (Fe(III)) ions before adding it to water containing polystyrene microplastics.

Within minutes, the pectin reacted with the iron ions and formed a gel network. This network trapped the plastic particles and created visible fibrous flocs. According to the researchers, electrostatic (Coulombic) forces helped the gel bind the particles together. The flocs could then be removed from the water.

The method removed 95.3% of 1.0 μm polystyrene microplastics. It also removed 87.4% of polystyrene nanoplastics measuring approximately 100 nm. These results show that the process works effectively across different particle sizes.

Turning Waste Into A Valuable Resource

The researchers also tested wastewater from washing nameko mushrooms instead of preparing fresh mucilage. Surprisingly, this by-product performed even better. It removed 98.4% of the microplastics.

This result suggests that mushroom processing plants could reuse their wastewater as a water treatment resource instead of treating it as waste. Such an approach could reduce waste streams while creating additional value from food processing.

Unlike many conventional chemical flocculants, the nameko-based alternative comes from renewable biological materials. It is also biodegradable and non-toxic. In addition, the resulting flocs biodegrade after treatment, which further reduces the environmental impact.

More research is still needed before large-scale implementation becomes possible. However, the study demonstrates how naturally derived materials could support more sustainable wastewater treatment. It also highlights a promising approach to reducing microplastic pollution.

Source: Shinshu University / EurekAlert!
Photo: Hillbourne