Sustainable Decentralized Water Purification: Simultaneous Disinfection of Pathogenic Fungi and Degradation of Herbicide Via an Electrochemically Driven UV-LED/Cl2 Process

The electrochemically driven UV light-emitting diode/chlorine (UV-LED/EC-Cl₂) process represents an emerging advanced oxidation technology capable of simultaneously removing microorganisms and micropollutants, making it particularly suited for decentralized water treatment in rural areas (utilized naturally occurring Cl^– in water). This research systematically investigated the removal efficiency and underlying mechanisms of the UV-LED/EC-Cl₂ process for the selected microorganisms (Aspergillus niger spores) and herbicides (atrazine (ATZ) and 2,4-dichlorophenoxyacetic acid (2,4-D)). The results demonstrated a significant synergistic effect in fungal spore inactivation, primarily attributed to the generation of reactive radical species, which induced severe membrane disruption and elevated intracellular reactive oxygen species levels. Furthermore, the UV-LED/EC-Cl₂ process exhibited exceptional herbicide removal efficiency, achieving over 90% degradation within 37 min. The coexistence of A. niger spores reduced the herbicide degradation efficiency by approximately 10%, with the degradation products of ATZ exhibiting increased molecular weight and toxicity. Even in actual groundwater, the UV-LED/EC-Cl₂ process maintained a high removal efficiency. Additionally, the electrical energy per log removal of herbicide ranged from 18.3 to 32.5 kWh/m³-log, lower than that of the standalone processes. These findings underscore the potential of the UV-LED/EC-Cl₂ process as an effective and energy-efficient solution for simultaneous microorganisms and micropollutant removal in decentralized water treatment.