Atlantic City treatment plant filters microplastics with a plant-inspired system

Some wetland plants repel water, and plastic particles stick to them. Nathaniel Banks and Yidian Liu, former Princeton University graduate students, borrowed that idea to build a filter. It is now running permanently at the Atlantic County Utilities Authority (ACUA) wastewater plant in Atlantic City, New Jersey, which discharges its treated water into the Atlantic Ocean.

Their company, PolyGone Systems, calls the system PolyPod: treated water leaving the plant flows through it, and the water-repelling microplastics stick to it before they reach the sea. The plant has installed two units after a two-year pilot that began in 2024.

PolyGone’s filters at sunset at the Atlantic City plant. Image: PolyGone Systems.

What has been measured, and what hasn’t

According to ACUA, the system captured more than 580 million microplastic particles a year during the pilot. In the lab, its founders say, it removed more than 98% of microplastics, and it works best on the smallest particles.

The caveat: there is no data yet for the permanent system, and the utility’s claim that it is the first of its kind in the world has not been independently checked. No US rule currently requires microplastics to be removed from wastewater.

From the washing machine to the sea

Treatment plants receive microplastics from factories, from rain that washes off tyre particles and from household laundry. “We’re discharging to the ocean,” said ACUA president Matt DeNafo: whatever isn’t removed there ends up at sea.

PolyGone has launched a similar system at a wastewater plant in California and is looking at a smaller version for homes.