How Greer CPW used nanobubbles to eliminate foaming and cut treatment costs

How are nanobubbles used in wastewater treatment?

Nanobubbles are gaining attention across the water sector because they behave differently from the bubbles produced by traditional aeration systems. Nanobubble technology does not replace conventional aeration, which remains the primary method wastewater plants use to supply oxygen to microorganisms that treat wastewater.

In most plants, aeration works by blowing air into the water to deliver oxygen for biological treatment. These bubbles rise quickly to the surface and release oxygen as they move through the tank.

Nanobubbles serve a different function. Thousands of times smaller than a grain of salt, they remain suspended in the water rather than rising rapidly. This extended contact time allows them to interact with compounds such as surfactants, the soap-like industrial ingredients that create foam and interfere with treatment.

Because nanobubbles remain in the water longer, they can help break apart compounds like surfactants before they cause problems downstream. Greer CPW, the public utility serving the City of Greer in upstate South Carolina, was dealing with a high concentration of surfactants in their wastewater.

The utility’s wastewater treatment plant handles roughly three million gallons per day and serves both residents and a significant number of local industries. During winter, the plant faced recurring operational issues linked to surfactants entering the treatment process.

Why is foaming a recurring wastewater treatment challenge?

Winter created the toughest conditions for the utility, when industrial production cycles led to more unstable, surfactant-rich wastewater entering the plant. These surfactants from industrial users resist breaking down and can generate thick layers of foam.

At Greer, this foam often accumulated in the equalization basin, the tank that holds and blends incoming wastewater, and at times it rose more than two feet high.

To keep the system running, operators added significant amounts of chemicals — first to control the foam, and then to help solids settle when the treatment process became unbalanced. On the most challenging days, the plant spent up to $2,500 on chemicals alone. The team needed a solution that addressed the source of the problem, not just the symptoms.

How did Greer test the potential of nanobubbles?

The utility partnered with Xylem and Moleaer, the manufacturer and provider of its patented nanobubble technology, to explore whether nanobubbles could help reduce the surfactants causing the foaming. Moleaer had been working with Xylem through the Xylem Innovation Labs’ accelerator program, which created an opportunity to accelerate adoption of the technology for municipal and industrial wastewater treatment plants worldwide.

Black & Veatch served as the project’s engineering partner, helping plan the pilot, set up the system, and support day-to-day monitoring once it began. Their involvement ensured the pilot was designed to operate safely within the plant’s existing processes and meet regulatory requirements.

The pilot ran during Greer’s toughest months. A nanobubble generator and air compressor were installed in a temporary space. Water from the equalization basin was pumped through the generator, infused with nanobubbles, and returned to the main flow. This allowed the utility to test the technology under real conditions without making permanent changes to its infrastructure.

Pilot results showed rapid improvements and lasting stability

The impact was visible almost immediately. Foam levels began dropping soon after the system was activated, and within a few weeks operators were able to turn off all defoaming chemicals. As the plant stabilized, they also shut off their settling chemicals, including aluminum-based products and polymers, which had been needed to counteract the disruption caused by surfactants.

Throughout the winter, the plant operated with no chemicals for foaming or settling. Solids levels stayed manageable, and settling performance improved. Even when the plant experienced higher-than-normal organic loading — conditions that typically challenged the system in winter — it remained stable and in compliance.

A practical step toward more affordable and resilient treatment

The Greer CPW pilot shows how a targeted, low-disruption approach can help utilities reduce costs and improve reliability without major system upgrades. As many wastewater plants face rising chemical prices and more complex incoming wastewater, tools that strengthen existing processes are increasingly valuable. By supporting and helping utilities test technologies like nanobubbles, Xylem plays an active role in maintaining affordable, dependable wastewater treatment for the communities they serve.