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News of November 6, 2023

Combating emerging pollutants with bubbles

HZDR engineer presents innovative water treatment method at Falling Walls competition

Pharmaceuticals, pesticides, or microplastics – some of the substances polluting water bodies worldwide have only been identified in recent years. They are classified as “emerging pollutants”, posing threats to both nature and human health. Until now, there has been no method to combat them effectively. At the Helmholtz-Zentrum Dresden-Rossendorf (HZDR), Amit Kumar is researching a solution that harnesses the energy of imploding gas bubbles in order to neutralize these types of contaminants in wastewater treatment plants and other facilities. On November 7, he will present his idea at the Falling Walls competition in Berlin.

Foto: Amit Kumar ©Copyright: HZDR

Amit Kumar presents the method of hydrodynamic, cavitation-based oxidation at the Falling Walls competition. It is also one of the topics that the HZDR postdoc is researching at the Clean Water Technology Lab - CLEWATEC.

Source: HZDR


Water pollution is a global challenge with emerging pollutants accounting for the majority of the problem. Besides the examples mentioned, residues from industrial chemicals and personal care products are also grouped under this term. They all share the characteristic that their presence in the environment – in drinking water, surface water, or groundwater – has only been discovered in the 1990s or later. Often, their interactions with other chemicals and organisms are complex and not fully understood, making them a difficult-to-assess risk, for example to aquatic ecosystems.

Oxidation puts contaminants out of action

Wastewater treatment plants play a crucial role in removing these pollutants, but they face limitations when dealing with chemically stable compounds. Amit Kumar’s method, the hydrodynamic cavitation-based oxidation, addresses this issue. Using a high-pressure pump, a pressure difference is created in the liquid, inducing the formation and collapse of gas bubbles inside the plants. The crucial components are the reactive hydroxyl radicals released during the implosion of these bubbles. They can attach to the pollutants and oxidize them into small, inactive fragments. To generate the desired number of hydroxyl radicals, the researchers also add ozone to the process.

“The advantage of this combined cavitation-based method is its applicability to a wide range of emerging pollutants. Furthermore, it is friendlier to the environment compared to other solutions, because no solid waste is generated”, explains Amit Kumar, who works on this topic at HZDR’s Clean Water Technology Lab – CLEWATEC together with his colleague Ysabel Huaccallo Aguilar. “We hope that this technology, which is currently in the research and development phase, will be used in various fields. It is suitable for municipal and industrial wastewater treatment, as well as for agriculture and the treatment of drinking water.”

With his idea, Amit Kumar is now competing at the annual Falling Walls Engage event, which is aimed at young inventors, researchers, start-up entrepreneurs, and students. He had previously emerged as the winner of a qualifying round in Hanover, the "Summer School on Global Solutions for Water Security", at the end of September, securing him a place in the final. There, he will have the opportunity to present his project in a 5-minute pitch to a top-class jury and international audience following the "Science Engagement" contest.

From the Danube to the Elbe River

Amit Kumar was born and raised in India. He studied at the universities in Girona (Spain) and Belgrade (Serbia) within the Marie Skłodowska-Curie Innovative Training Network of the European Union, where he obtained his PhD in Environmental Engineering in 2022. Afterwards, he joined HZDR in February this year and continued his scientific career in Dresden at CLEWATEC, which explores innovative solutions in water treatment at the intersection between industry and science. In addition to researching emerging pollutants, Amit Kumar also investigates how computer-based simulations can help in better understanding the physical phenomenon of cavitation.

“Falling Walls” is sponsored by the Federal Ministry of Education and Research (BMBF), the Helmholtz Association, and the Robert Bosch Foundation. Numerous scientific institutions and foundations are also involved, including acatech – German Academy of Science and Engineering, the Leibniz Association, the Fraunhofer Society, the Max Planck Society, the German Academic Exchange Service (DAAD) and the Körber Foundation. The event was first held in 2009 on the anniversary of the fall of the Berlin Wall. The motto then and now: breaking down walls and pushing boundaries in science.

Further information:

Dr. Sebastian Reinecke
Institute of Fluid Dynamics at HZDR
Email: | Phone: +49 351 260 2320

Media Contact:

Simon Schmitt | Head
Communications and Media Relations at HZDR
Phone: +49 351 260 3400 | Email: