AQUA-CLEAR: Advanced Cavitation for PFAS Treatment and Circular Water Management

Description

Per- and polyfluoroalkyl substances (PFAS) are synthetic “forever chemicals” whose extremely stable carbon-fluorine bonds make them exceptionally resistant to degradation. They can pass through conventional treatment systems to accumulate in drinking water, wastewater, and landfill leachate worldwide. After decades of use in firefighting foams, non-stick coatings, waterproof textiles, and food packaging, they now threaten public health, causing immune suppression, cardiometabolic diseases, and developmental disorders. At the same time, they circulate endlessly through the water system.

Removing these chemicals is critical to protecting the integrity of natural water sources, preventing long-term ecological damage, and preserving water quality for future generations. Current technologies struggle to do more than move the problem elsewhere. Granular activated carbon and ion exchange resins capture PFAS but create secondary solids that must be further incinerated. Reverse osmosis and nanofiltration pressurize PFAS into a toxic brine that still requires costly disposal, and both processes consume significant amounts of energy. Advanced oxidation, plasma arcs, and high-temperature reactors can break carbon-fluorine bonds, but at a high cost: large energy loads, aggressive chemicals, and a significant carbon footprint. In conclusion, there are currently no commercial solutions that combine complete mineralization and degradation with moderate energy use and economic viability.

Our solution for purifying water is based on hydrodynamic cavitation, which involves the formation, oscillation and finally the collapse of microbubbles that release a lot of energy to the system in the form of

• mechanical effects where we usually talk about shock waves and microjets that impact the substances,
• thermal effects with local and transient temperature increase up to 5000 K

and last but not least,

• chemical effects where the water molecules decompose into free radicals, such as hydroxyl and hydrogen

which all contribute to the efficient chemical oxidation of PFAS.

Preliminary results from concept-tested HC reactors have shown efficient degradation of PFAS, achieving simultaneous reduction of 11 of the most widespread PFAS compounds. It is worth noting that a treatment efficiency of 36% was observed within 30 minutes of operation, even at concentrations below 10 ng/L, levels relevant for safe drinking water. This is achieved solely by harnessing the kinetic energy of the water flow at the wastewater treatment plant, without the need for any external pump or energy source, as our reactor is powered entirely without electricity.

We aim to develop a new generation of hydrodynamic cavitation reactors (HC), validated at pilot scale and tailored for integration into our industrial partner's wastewater treatment plant. Deploying a "plug-and-play" cavitation reactor will help treatment plants meet the upcoming EU and WHO limit values of 4 ng L⁻¹ without exporting toxic residues. Cleaner water protects public health, fisheries and irrigated agriculture, and the modest power consumption reduces greenhouse gas emissions. Swedish industry is gaining an early foothold in the emerging market for compact PFAS destruction modules, strengthening national leadership in sustainable technology.

The Royal Institute of Technology contributes world-leading expertise in multiphase fluid dynamics, cavitating flows, mechanical and chemical effects of cavitation. In particular, KTH will design the cavitation reactor using both cleanroom facilities and 3D printing. IVL The Swedish Environmental Research Institute contributes significant expertise in PFAS reduction, having evaluated key treatment technologies under real-world conditions at the SWIC pilot project and in several Swedish wastewater treatment plants, where the HC unit will be compared with established methods. Together, KTH and IVL steer the HC concept from laboratory prototype to industrial implementation within the project lifetime.

Publications

Peer-review Paper

Talabazar FR, Baresel C, Ghorbani R, Tzanakis I, Koşar A, Grishenkov D, Ghorbani M. Removal of per-and polyfluoroalkyl substances (PFAS) from wastewater using the hydrodynamic cavitation on a chip concept. Chemical Engineering Journal. 2024 Sep 1;495:153573

Patent

GRISHENKOV D, TALABAZAR FR, KOŞAR A, AGHDAM AS, GHORBANI M, inventors; Sabanci Üni̇versi̇tesi̇ Nanoteknoloji̇ Araştirma Ve Uygulama Merkezi̇, Sabanci Üni̇versi̇tesi̇, assignee. A new method to generate vigorous cavitation through the microscale device at low pressure for wastewater treatment. 2024 Jan 11.

Rewards

This work has been acknowledged by The Royal Swedish Academy of Engineering Sciences (IVA) and included in the list of 100 projects that are deemed to offer the greatest potential.

Title: Cavitating microbubbles as a next generation water cleaning technology

Link: https://www.iva.se/det-iva-gor/utmarkelser/ivas-100-lista/cavitating-microbubbles-as-a-next-generation-water-cleaning-technology/

Collaborations

• Sabanci University
• KTH – Royal Institute of Technology
• IVL - The Swedish Environmental Research Institute
• Oxford Brookes University
• Gdansk University of Technology
• Borçelik

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