The first meeting brought together all partner organisations of the Centre, while the second, held on 16 October 2026, focused on the work of the research teams at Sofia University "St. Kliment Ohridski". Both meetings aimed to review the results achieved, coordinate upcoming activities and explore opportunities for the practical application of the technologies under development.

The fifth working meeting of the partner organisations brought together representatives of the institutions combining their expertise within Clean&Circle:

• Sofia University "St. Kliment Ohridski" — lead organisation;
• University of Architecture, Civil Engineering and Geodesy;
• University of Forestry;
• Prof. Dr. Assen Zlatarov University — Burgas;
• Institute of Physical Chemistry "Acad. Rostislav Kaishev" — Bulgarian Academy of Sciences (BAS);
• Institute of Organic Chemistry with Centre of Phytochemistry — BAS;
• Stephan Angeloff Institute of Microbiology — BAS;
• Cleantech Bulgaria Foundation.

Participants discussed progress in research activities, ongoing experiments and the development of technological solutions. Particular attention was paid to the prospects for the practical application of the results in water management and treatment, waste treatment and the efficient use of resources. The discussions provided an opportunity to exchange ideas, align priorities and coordinate upcoming tasks among the partner organisations.

The second meeting brought together representatives of the Faculty of Biology, the Faculty of Physics and the Faculty of Chemistry and Pharmacy at Sofia University. It focused on the specific contributions of the university's research teams to the implementation of the PNIIDIT-funded project and the activities planned for the remainder of the year.

The meeting was opened by Assoc. Prof. Ivaylo Yotinov, PhD, Coordinator of Clean&Circle, who presented the current status of the project and outlined the main upcoming tasks. He reviewed recent scientific and public engagement initiatives, including participation in the European Researchers' Night, a meeting with the GIS-Transfer organisation and the first successful doctoral dissertation defence by a doctoral researcher at the Centre, Dr. Magdalena Bogdanova.

Chief Assist. Prof. Yordan Karapenchev, PhD, presented the new Clean&Circle website. Its development aims to improve the presentation of the Centre's scientific activities and research results, while facilitating access to information for researchers, business representatives and other interested audiences.

Assoc. Prof. Evgenia Benova reviewed the achievement of the project's result indicators and the progress made in 2026. She emphasised the need for timely implementation of planned activities and effective coordination among the teams, particularly in view of the approaching end of the calendar year.

Assoc. Prof. Yovana Todorova presented the work of the Faculty of Biology on developing indicator-based methods for water monitoring and investigating fluorescence indicators of pollution. The reported activities included joint experiments examining the effects of plasma treatment on bacterial suspensions, as well as the preparation of new scientific publications.

Assoc. Prof. Elitsa Pavlova, PhD, presented the contribution of the Faculty of Physics to the experimental assessment of water purity and contamination using a method for measuring adenosine triphosphate (ATP). The research involves comparisons between control samples and water treated under different experimental conditions, contributing to the evaluation of the technological approaches under investigation.

Assoc. Prof. Valentina Lyubomirova reported on the results achieved by the Faculty of Chemistry and Pharmacy, highlighting three scientific publications in first-quartile (Q1) journals. The studies address the composting of garden waste, pollution and microbial communities in aquatic ecosystems, and an analytical method for extracting the radionuclide caesium-137.

During the discussions among the university research teams, participants reviewed scientific publication activity, cooperation with businesses and the development of research results with potential for intellectual property protection. They also discussed the next steps towards closer collaboration between the different research fields and the translation of scientific results into practical solutions.

The implementation of the PNIIDIT-funded project supports the maintenance of modern research infrastructure and the further development of Clean&Circle's scientific expertise. The project aims to develop and implement clean technologies for sustainable water and waste management, resource efficiency and the advancement of the circular economy.