The phenomenon of cavitation is currently one of the most researched processes to support many classical approaches used in chemical and environmental engineering. The ability to concentrate high energy and pressure while significantly increasing mass transfer, mainly through the formation of microcirculations, has already been utilized for water and wastewater treatment in advanced oxidation processes (AOPs) based on cavitation. Currently most studies focus on typical Venturi tube or orifice cavitation systems. These systems, which mainly contain a constriction in the treatment line, force a high recirculation rate of the treated medium – 50 to even 200 cycles are required for an effective degradation of the pollutants.

In contrast, the current project relates to unique studies of cavitation phenomena in micro-channels and micro-channel arrays that allow cavitation effects to be intensified by taming cavitation bubbles in a controlled environment in multiple parallel lines. To study such systems, a detailed research plan includes tasks related to the design and characterization of such cavitation zones; a detailed analysis of the fundamentals of cavitation occurring in micro-channels; the definition of optimal conditions and behavior of the liquid and gaseous phase; the study of the differences between micro- and macrocavitation in terms of phase behavior, oxidant’s activation, radical’s formation, and organic pollutant degradation mechanisms.

Several important insights will be gained in this project that will have a strong impact on future studies in this area. These include the knowledge and visualization of cavitation generated in micro-channels and procedural approaches to describe and optimize the phenomenon, and the description of the mechanisms of oxidant’s activation, radical’s formation, and organic pollutant degradation.

The results of this project should also be useful for further studies on the application character of Cav-Micro reactors. It is expected that at least 6 milestone papers will be published in high-ranking JCR journals. These papers will provide basic knowledge, rules, and methods for conducting further studies in this field. It is therefore expected that the published research papers will achieve high recognition in the field and a high citation rank.

WP1: Project management (M1-M36) [led by both PIs]. The purpose of this WP is to ensure that the project is running according to the established schedules. 

T1.1 Progress and cost reporting (M1-M36)

T1.2 Monitoring, control and quality management (M1-M36)

WP2: Studies on cavitation for downscale from macro- to micro-channels (M1-M12) [led by M. Zupanc]. WP2 includes studies on cavitation for downscale from macro to micro geometries for better control of cavitation effects.

T2.1 Design and manufacture of micro-channels (M1-M12) [led by SI]

T2.2 Characterization of cavitation in micro-channels (M7-M12) [led by SI]

T2.3 Comparison of chemical effects between macro- and micro-channels (M7-M12) [led by PL]

WP3: Studies on degradation of pollutants in macro- and micro-channels (M1-M22) [led by G. Boczkaj]. The purpose of this WP is to firstly develop and optimize the analytical methods for determination of the selected pollutants and to investigate their degradation using existing macro- and newly developed micro-channels.

T3.1: Development and optimization of an analytical method (M1-M6) [led by PL]

T3.2: Degradation of pollutants in macro- and micro-channels (M7-M22) [led by PL]

T3.3: Characterization of cavitation in macro- and micro-channels with pollutants (M11-M17) [led by SI]

WP4: Studies on activation of external oxidants in macro- and micro-channels (M13-M24) [led by G. Boczkaj]. The purpose of this WP is to firstly optimize macro- and micro-channels for the administration of external oxidants and characterization of the developed cavitation.

T4.1: Evaluation of degradation effectiveness and mechanisms in presence of external oxidants (M13-M24) [led by PL]

T4.2: Characterisation of cavitation in macro- and micro-channels with external oxidants (M17-M24) [led by SI]

WP5: Micro-channel array development (M25-M36) [led by M. Zupanc].

T5.1 Development and design of micro-channel array (M25-M33) [led by SI]

T5.2 Evaluation of the degradation of pollutants by micro-channel arrays (M28-M33) [led by led by PL]

T5.3 Comparison of micro-channel array with a single macro-channel (M31-M36) [led by SI]

WP6: Holistic analysis of project results (M30-M36) [led by both PIs]. The aim of this WP is to find general conclusions of the project and perform overall analysis of the data.

 Tasks will be focused on:

• selection of optimal conditions and processes for degradation of individual groups of chemical compounds under cavitation in micro-channels;
• description of reaction mechanisms and its kinetics, comparison of reaction pathways between micro- and macro-channels;
• defining similarities and differences between micro- and macro-channels.

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