Research projects are (co)financed by the Slovenian Research and Innovation Agency
- Member of the University of Ljubljana: Faculty of Mechanical Engineering
- Project code: J2-4480
- Science: Engineering sciences and technologies
- SICRIS: Removal of selected antimicrobials by plasma-cavitation hybrid technology from water matrices of varying complexity (Causma)
Along with the growth of the global population and rising living standards, environmental pollution is also increasing. One of the most pressing global challenges is the growing contamination of surface and groundwater, which is leading to a worldwide shortage of water resources. Over the past decade, sufficient evidence has accumulated showing that pharmaceutical compounds continuously enter the aquatic environment through wastewater treatment plants, negatively affecting it. The problem is further exacerbated when hospital wastewater, containing high concentrations of various antimicrobial agents, including antibiotics, is discharged directly into sewage systems.
Authorities in the European Union have addressed this issue by compiling a list of priority substances whose emissions into the environment must be closely monitored. Data collected through this initiative will lead to stricter regulations by defining acceptable environmental concentrations of these compounds in wastewater treatment plant effluents. Pharmaceuticals have become an indispensable part of modern life, and since their use is unlikely to decrease, their negative environmental impact will continue to grow. The situation appears highly challenging, with no clear short-term solution. The most appropriate approach is therefore to upgrade conventional wastewater treatment processes with alternative technologies.
In line with EU concepts for clean and sustainable wastewater treatment, the proposed Causma project focuses on developing an alternative, environmentally friendly, and economically viable treatment technology. Advanced oxidation processes are a powerful tool for the oxidation and even mineralization of many hazardous pollutants in water matrices of varying complexity, thereby reducing their environmental impact. Within the Causma project, we will investigate the effectiveness of two such processes: hydrodynamic cavitation and non-thermal plasma. Although both processes have proven effective individually, there is little to no data on their combined performance. The Causma project will address this gap by innovatively integrating both processes into a hybrid technology. In combination, the oxidation potential is maximized while energy input is minimized.
The efficiency of the individual processes and their combination will be evaluated for selected pharmaceutical compounds, particularly antimicrobials from the priority list: erythromycin, clarithromycin, azithromycin, amoxicillin, ciprofloxacin, sulfamethoxazole, and trimethoprim. The performance of the combined technology will first be assessed in Milli-Q water and subsequently validated using real hospital wastewater samples.
We believe that the combination of hydrodynamic cavitation and non-thermal plasma can deliver a wastewater treatment technology that is simple, environmentally friendly, economically feasible, robust, and readily scalable to the industrial level.
WP1: Project management (M1-M36)
Task 1.1 Progress and cost reporting (M1-M36)
Task 1.2 Monitoring, control and quality management (M1-M36)
Project management was carried out appropriately. Regular meetings of the project team members, as well as meetings between the project leader and work package leaders, were organized. Effective management led to the successful achievement of all three project objectives.
WP2: Development and optimization of an analytical method (M1-M12)
Task 2.1: Development of rapid quantitation methods in simple matrices (M1-M5)
Task 2.2: Development of multiple reaction monitoring methods (M4-M12)
Within WP2, our objective was to develop and optimize an analytical method for the determination of selected pharmaceutical compounds in a simple Milli-Q water matrix. The method was developed, calibrated, and validated according to standardized procedures. It proved to be stable, meaning that degradation products do not interfere with the measurement of the parent compound. The results from WP2 are essential for WP3–WP5, where the analytical methods are applied to evaluate the performance of optimized cavitation and plasma systems. The findings were presented at three international conferences [1–3].
WP3: Optimization of RGHC (M1-M12)
Task 3.1: Controlling cavitation and suction performance of the RGHC (M1-M8)
Task 3.2: Characterisation of cavitation in the RGHC (M6-M10)
Task 3.3: Study of cavitation erosion (M9-M12)
Within WP3, we influenced cavitation conditions in the RGHC by modifying the geometry of the rotor and stator. Through cavitation characterization using high-speed visualization, pressure pulsation measurements, and monitoring of chemical effects based on analytical methods developed in WP2, we identified the “optimal” geometry to achieve the desired mechanical and chemical effects of the RGHC. The results were presented in five scientific publications [4,5,8,9,10] and at several scientific conferences [1,3,6,7]. Three of these publications also include fundamental studies on the effects of cavitation in other liquids, exceeding the originally planned scope of WP3.
WP4: Serial coupling of the venturi-plasma device with the RGHC (M13-M24)
Task 4.1: Optimization of the venturi-plasma device (M13-M18)
Task 4.2: Measurements of discharge and plasma parameters (M15-M18)
Task 4.3: Serial coupling of venturi-plasma with RGHC (M17-M21)
Task 4.4: Device optimization for the removal of antimicrobials (M18-M23)
Task 4.5: Energy efficiency evaluation (M23-M24)
Within WP4, the RGHC developed in WP3 was coupled with a Venturi constriction, where a stable supercavitation cloud was generated using the RGHC and gas plasma was ignited within it. The position and configuration of the electrodes were optimized, and the Venturi section was protected by an international patent [14]. The generated plasma inside the Venturi constriction was characterized using optical emission spectroscopy, while spatial optical spectroscopy enabled determination of plasma intensity and gas temperature. The results were also presented at scientific conferences [6,11,12,13]. The concept of coupling cavitation and plasma technology was demonstrated and published in a scientific journal [15]. In addition, further fundamental studies were carried out within WP4 and published in a scientific article [16].
WP5: Construction of a novel hybrid plasma-cavitation device (M24-M36)
Task 5.1 Design and construction of a RGHC with integrated plasma (M25-M30)
Task 5.2 Device optimization for the removal of selected antimicrobials (M30-M35)
Task 5.3 Energy efficiency evaluation (M34-M36)
A novel hybrid device was designed, constructed, and tested. The design enables stable operation of gas plasma within the cavitation chamber. Its functionality was demonstrated at the Bfestival [17]. An international patent application has been filed for the device [18]. The final results are presented in a scientific publication [19], and the research data are openly available on the Zenodo repository [20].
WP6: Dissemination and exploitation of the results (M1-M36)
T6.1 Presentation of the results to the scientific community (M7-M36)
T6.2 Presentation of the results to the general public (M1-M36)
T6.3 Presentation of the results to the industrial community (M34-M36)
Work within WP6 was carried out appropriately and fulfilled the planned activities. The results have been disseminated to the scientific community through eight open-access publications in scientific journals and presentations at more than ten scientific conferences, while summaries are available to the general public on the website of the Faculty of Mechanical Engineering, University of Ljubljana.
[1] ZUPANC, M., PETKOVŠEK, M., PRIMC, G., ROŠKAR, R., ZAPLOTNIK, R., TRONTELJ, J.. Removal of bisphenol A by plasma-cavitation technology (Causma): presentation at the Water Innovation and Circularity Conference (WICC), 7.-9.6.2023, Athens. [COBISS.SI-ID 156037891]
[2] ZUPANC, M., PETKOVŠEK, M.. Cavitation exploitation, beyond the scope of CABUM: keynote at the Workshop on cavitation exploitation 2023. [COBISS.SI-ID 181856771]
[3] ZUPANC, M., GOSTIŠA, J., PETKOVŠEK, M., DULAR, M.. Process intensification through cavitation. Next Challenges of Biorefineries: book of abstracts: 3rd BioSPRINT Workshop [and] 2nd Bilateral Workshop Portugal – Slovenia : June 14-15, 2023, National Institute of Chemistry, Slovenia. [COBISS.SI-ID 156089859]
[4] ZUPANC, M., BRAJER HUMAR, B., DULAR, M., GOSTIŠA, J., HOČEVAR, M., KOLBL REPINC, S., KRZYK, M., NOVAK, L., ORTAR, J., PANDUR, Ž., STRES, B., PETKOVŠEK, M.. The use of hydrodynamic cavitation for waste-to-energy approach to enhance methane production from waste activated sludge. Journal of environmental management. 2023, [COBISS.SI-ID 167876867]
[5] ZUPANC, M., ZEVNIK, J., FILIPIĆ, A., GUTIÉRREZ-AGUIRRE, I., JEŠELNIK, M., KOŠIR, T., ORTAR, J., DULAR, M., PETKOVŠEK, M.. Inactivation of the enveloped virus phi6 with hydrodynamic cavitation. Ultrasonics Sonochemistry. 2023, [COBISS.SI-ID 148619523]
[6] FILIPIĆ, A., DOBNIK, D., RAVNIKAR, M., KOŠIR, T., PETKOVŠEK, M., ZUPANC, M., ZEVNIK, J., ORTAR, J., DULAR, M., MOZETIČ, M., ZAPLOTNIK, R., PRIMC, G., GUTIÉRREZ-AGUIRRE, I.. Cavitation alone or in combination with plasma for waterborne virus inactivation. Workshop on Cavitation Exploitation, 20th – 22nd of September 2023, Ljubljana, Slovenia [COBISS.SI-ID 167612931]
[7] GOSTIŠA, J., DULAR, M., STEPIŠNIK PERDIH, T., ZUPANC, M.. On the path to pin disc hydrodynamic cavitation reactor commercialisation. Workshop on Cavitation Exploitation, 20th – 22nd of September 2023, Ljubljana, Slovenia. [COBISS.SI-ID 167604227]
[8] BOČEK, Ž., PETKOVŠEK, M., CLARK, S. J., FEZZAA, K., DULAR, M.. Dynamics of oil–water interface at the beginning of the ultrasonic emulsification process. Ultrasonics Sonochemistry. 2023, [COBISS.SI-ID 170581251]
[9] BOČEK, Ž., PETKOVŠEK, M., CLARK, S. J., FEZZAA, K., DULAR, M.. Kelvin-Helmholtz instability as one of the key features for fast and efficient emulsification by hydrodynamic cavitation. Ultrasonics sonochemistry. 2024, [COBISS.SI-ID 201951491]
[10] ZUPANC, A., PETKOVŠEK, M., ZDOVC, B., ŽAGAR, E., ZUPANC, M.. Degradation of hydroxypropyl methylcellulose (HPMC) by acoustic and hydrodynamic cavitation. Ultrasonics Sonochemistry. 2024, [COBISS.SI-ID 204078851]
[11] PRIMC, G., ZAPLOTNIK, R., FILIPIĆ, A., DOBNIK, D., GUTIÉRREZ-AGUIRRE, I., RAVNIKAR, M., KOŠIR, T., ŽEGURA, B., PETKOVŠEK, M., DULAR, M., BAEBLER, Š., ŠTERN, A., MOZETIČ, M.. Cold plasma within a stable supercavitation bubble – a breakthrough technology for efficient inactivation of viruses in water. V: AAPPS-DPP2025 : 9th Asia-Pacific Conference on Plasma Physics : September 21-26, 2025, Fukuoka International Congress Center, Japan. [COBISS.SI-ID 255120131]
[12] PRIMC, G., ZAPLOTNIK, R., MOZETIČ, M., FILIPIĆ, Ar., DOBNIK, D., GUTIÉRREZ-AGUIRRE, I., ROŠKAR, R., TRONTELJ, J., PETKOVŠEK, M., DULAR, M., ZUPANC, M.. A combination of advanced oxidation processes to tackle the degradation of organic matter. V: ICREM 2024 : abstract book : The 6th International Conference on Radiation and Emission in Materials : 27-29 November 2024, Khon Kaen, Thailand. [COBISS.SI-ID 220948739]
[13] PRIMC, G., FILIPIĆ, A., MOZETIČ, M., DULAR, M., PETKOVŠEK, M., ŠTERN, A., ŽEGURA, B., GUTIÉRREZ-AGUIRRE, I., DOBNIK, D., ZAPLOTNIK, R.. Combining advanced oxidation techniques for disinfection of water for (closed) irrigation. Japan-Croatia Joint Symposium on Chemical Engineering & Plasma Agriculture for Young Scientists Global Networking (JC-JSChEPA) : book of abstracts : Zagreb, Croatia, October 15 – 17, 2024. Zagreb: [University of Zagreb, Faculty of Chemical Engineering and Technology], [COBISS.SI-ID 213768963]
[14] PRIMC, G., ZAPLOTNIK, R., MOZETIČ, M., FILIPIĆ, A., GUTIÉRREZ-AGUIRRE, I., DOBNIK, D., DULAR, M., PETKOVŠEK, M.. Method and device for disinfection of liquid: United States Patent US 11,807,555 B2, 2023-11-07. Alexandria: United States Patent and Trademark Office, 2023. [COBISS.SI-ID 45799939]
[15] ZUPANC, M., PRIMC, G., DULAR, M., PETKOVŠEK, M., ROŠKAR, R., ZAPLOTNIK, R., TRONTELJ, J.. Proof-of-concept for removing micropollutants through a combination of sub-atmospheric-pressure non-thermal plasma and hydrodynamic (super)cavitation. Ultrasonics Sonochemistry. 2024, [COBISS.SI-ID 212810499]
[16] MALEKI, M., TALABAZAR, F. R., DAVOUDIAN, S. H., DULAR, M., KOŞAR, A., PETKOVŠEK, M., ŠMID, A., ZUPANC, M., GHORBANI, M.. The formation of hydroxyl radicals during hydrodynamic cavitation in microfluidic reactors using salicylic acid dosimetry. Chemical engineering journal. 2025, [COBISS.SI-ID 230634243]
[17] DAHLE, S., ZUPANC, M., DULAR, M., PETKOVŠEK, M.. Distribution of plasma species with the help of hydrodynamic cavitation for synergistic effects in the degradation of water pollutants. BFestival 2025 : biotehnologija in trajnostni razvoj : predstavitev raziskovalnih dosežkov Biotehniške fakultete. Ljubljana: Univerza v Ljubljani, Biotehniška fakulteta, 2025. [COBISS.SI-ID 229408003]
[18] ZUPANC, M., PETKOVŠEK, M., GOSTIŠA, J., DULAR, M., DAHLE, S.. A combined cavitation and plasma generation system and a method of generating cavitation and a plasma : application No.: LU509844. Luxembourg: European patent office, 2025. [COBISS.SI-ID 225777667]
[19] ZUPANC, M., DAHLE, S., DULAR, M., PRIMC, G., ZAPLOTNIK, R., PETKOVŠEK, M.. Decolorization of reactive Red 120 by a novel hybrid hydrodynamic cavitation and non-thermal plasma reactor. Journal of industrial and engineering chemistry. 2026, [COBISS.SI-ID 271784963]
[20] ZUPANC, M., DAHLE, S., DULAR, M., PRIMC, G., ZAPLOTNIK, R., PETKOVŠEK, M.. Data from paper: Decolorization of Reactive Red 120 by a novel hybrid hydrodynamic cavitation and non-thermal plasma reactor. Genève: Zenodo. [COBISS.SI-ID 271804675]