“Scale-up of cold atmospheric plasma (CAP) source for the production of plasma activated water (PAW)“

This thesis explores the scale-up of cold atmospheric plasma (CAP) sources for producing plasma-activated water (PAW), valued for its unique chemical properties derived from reactive oxygen and nitrogen species (RONS). RONS contributes to PAW’s antimicrobial and oxidative properties, making it valuable in agriculture, healthcare, and environmental remediation. However, efficient large-scale PAW production remains challenging due to declining CAP efficiency with increasing water volumes. The work begins with a systematic review (submitted to Plasma Processes and Polymers) that examines current PAW production methods, analyzing CAP configurations and process variables such as RONS concentration, pH, and energy efficiency. The review highlights various CAP sources, including corona discharge, dielectric barrier discharge (DBD), and plasma jets, examining how parameters like gas type and water composition affect PAW chemistry. Critical challenges for scaling up have also been identified, especially in sustaining high RONS concentrations in larger treatment volumes. Experimental research progresses from a 0.5-liter corona discharge system to a 2-liter DBD setup, increasing the treatment volume fourfold while maintaining RONS concentrations and improving energy efficiency. The research scales PAW production to a 6-liter treatment volume using a multipin corona discharge. This setup addresses challenges such as plasma uniformity and water homogeneity through strategic source placement and mechanical stirring, providing a scalable solution ideal for applications needing large PAW quantities, like agricultural irrigation and soil treatment. Finally, a hybrid CAP source was developed to enhance RONS production further. The optimized design and configuration allowed for greater control over RONS production and improved energy utilization, leading to higher RONS concentrations in treated water than multipin corona. This thesis presents critical insights into parameters for efficient RONS production in large- scale treatments, effectively bridging laboratory results with industrial applications. These findings lay the groundwork for advancing PAW technology, establishing benchmarks for scaling plasma-water treatments across diverse industries.