This study compares the effects of nonthermal plasma treatment on quinine water solutions for two configurations—the corona‐like discharge and the gliding arc discharge (GAD). Different electrolytes were added to the quinine solutions to modify the initial pH and enhance electrical conductivity for plasma discharge ignition directly in the liquid. A slightly higher quinine decomposition rate of 2.9 μg W−1 after 5 min of the treatment was achieved by GAD. From measured spectra, it was found that the absorption maximum at 332 nm was split into two separated peaks in the acidic and basic solution. The study of the time stability of quinine solutions has revealed quinine instability and that postpreparation time has influenced the plasma treatment effect.

Reducing energy costs in Europe is more challenging than before due to extreme price increases. The use of local renewable energy sources is one way to contribute to this effort. In the case of spa resorts, the use of heat from hot springs for therapeutic baths is an option. It is necessary to cool down this thermal mineral water to a temperature acceptable to the human body. However, due to the high mineral content of this water, heavy fouling can be a problem for conventional heat exchangers. The purpose of this study is to identify the suitable cooling technology in terms of required cooling capacity and waste heat recovery capability. The cooling technology was selected on the basis of a literature search. A pilot cooling unit consisting of vacuum cooler and plate heat exchanger was designed and tested in a real spa resort for six months. Both selected technologies have demonstrated the ability to cool thermal mineral water in long-term operation, as well as the possibility to utilize waste heat for domestic hot water heating. However, fouling problems occur in the plate heat exchanger. The vacuum cooler demonstrated greater operational robustness and resistance to encrustation.