DBD plasma enables phase-dependent pollutant degradation and ecological detoxification in water-sediment systems

DBD enables simultaneous removal of SMX and BPA in water-sediment systems. • ·OH, 1 O 2 and ·O 2 − dominate plasma oxidation. • Phase distribution controls degradation efficiency. • Plasma transforms sediment structure and enhances pollutant desorption. • LCA/TEA show electricity use and cost limit scale-up feasibility. Emerging contaminants are frequently detected in environmental waters and sediments. However, limited attention has been given to their removal in coupled water-sediment systems. In this study, dielectric barrier discharge (DBD) plasma was employed as a chemical-free advanced oxidation technology to achieve in-situ generation of reactive oxygen species (ROS) for simultaneous remediation of sulfamethoxazole (SMX) (water phase dominant) and bisphenol A (BPA) (sediment-associated) in a water-sediment system. The results show that degradation efficiency is strongly dependent on applied voltage, O 2 flow rate, and sediment-to-water ratio, while initial pollutant concentration is a limiting factor due to ROS availability. ESR and quenching experiments confirmed that ·OH, 1 O 2 , and ·O 2 − are the dominant reactive species, with 1 O 2 and ·OH playing primary roles. LC-MS and DFT analyses revealed multiple oxidative pathways involving hydroxylation, bond cleavage, and ring-opening reactions. Predictive ECOSAR and T.E.S.T. analyses suggested lower toxicity for most identified transformation products, and selected algal and seed-germination bioassays showed reduced toxicity-related effects after treatment. Plasma treatment also altered sediment structure and extracellular polymeric substances (EPS), which may facilitate pollutant desorption and interfacial mass transfer. Gate-to-gate life cycle assessment (LCA) and techno-economic analysis (TEA) identified electricity consumption and capital cost as the main burdens within the assessed boundary. This work demonstrates that DBD plasma enables simultaneous degradation of water- and sediment-associated contaminants through coupled ROS-driven oxidation and sediment matrix restructuring, providing a sustainable strategy for complex environmental remediation. Download: Download high-res image (158KB) Download: Download full-size image