Microbubble-enhanced cold plasma (MB-CAP) for pathogen disinfection in water: a sustainable alternative to traditional methods.

Abstract

Ensuring access to safe drinking water is a key global priority. However, conventional disinfection methods often produce toxic disinfection byproducts (DBPs) such as trihalomethanes (THMs) and haloacetic acids (HAAs), which pose significant carcinogenic and environmental risks. Cold atmospheric plasma (CAP) has emerged as a promising alternative disinfection approach that generates reactive species in situ, without the need for added chemical reagents. It utilizes reactive oxygen and nitrogen species (RONS), ultraviolet (UV) radiation, and transient electric fields to effectively inactivate a wide range of waterborne pathogens. CAP disrupts microbial membranes, damages nucleic acids, and induces oxidative stress, rapidly inactivating bacteria, viruses, and fungi. A notable advancement in plasma-based water disinfection is microbubble-enhanced cold atmospheric plasma (MB-CAP), which significantly improves plasma-liquid interactions. Microbubbles (MBs) act as efficient carriers for RONS, greatly increasing the gas-liquid interfacial area and enhancing the mass transfer of RONS. This results in faster removal of pathogens compared to conventional CAP systems. Furthermore, MB-CAP offers localized and targeted treatment capabilities, making it particularly suitable for decentralized water systems, hospital wastewater, and high-load industrial effluents. This review thoroughly examines the mechanisms of microorganism inactivation by MB-CAP, reactor configurations, MB generation techniques, and disinfection performance. This review also discusses key challenges such as energy efficiency, scalability, and regulatory compliance. Future research should focus on developing hybrid CAP systems, integrating renewable energy sources, and implementing real-time monitoring tools to optimize treatment efficacy. Overall, the review highlights the transformative potential of MB-CAP as a next-generation sustainable water disinfection technology.