Assoc. Prof. Dr. Nina Rman is a guest lecture at the University of Szeged in Hungary, where she worked with Dr Szanyi Janos from the Department of Geology to investigate the potential for improving the reinjection of exploited thermal water into geothermal aquifers in the poorly adherent sands that characterise the Pannonian Basin. Szeged is considered to be the leading geothermal city in the area. Z 27 deep boreholes a large part of the city's district heating system will be adapted to the sustainable use of geothermal energy - using doublets and triplets. A key challenge is to increase the proportion of returned thermal water in poorly adhering sands, which requires careful planning and monitoring.

Key approaches that can significantly increase the proportion of recovered thermal water returned to the aquifer include:

• well-sited boreholes,
• Careful well activation,
• injection of fully purified/filtered water,
• gradual changes in the pressure regime,
• very detailed monitoring to quickly detect unwanted processes.

The experience gained will be used in the planning and construction of new reinjection wells in Slovenia, contributing to an even more sustainable use of geothermal energy.