Solar-light-driven inactivation of toxigenic Microcystis by floating photocatalytic mesh system: Insights on physiological mechanism and application.

Abstract

Harmful algal blooms (HABs) pose serious ecological and health risks with releasing waterborne toxins. In this study, a novel floating Bi₂WO₆-based photocatalytic mesh (BPM) system was developed for efficient water purification by targeting the inactivation of HABs-dominated Microcystis and detoxification of associated microcystins (MCs) under solar light irradiation. The superior flotation, durability and sunlight utilization of the BPM system were achieved by its super-hydrophobic surface, robust stainless-steel mesh carrier, and efficient light transmission, respectively. Photocatalytic Microcystis inactivation and MCs degradation were achieved within 6 h at a bloom density of 5 × 10⁶ cells/mL through dual mechanisms, which are free radicals generation and direct physical cell disruption. Additionally, the physiological response in Microcystis exhibited a time-dependent inactivation process. The photosynthetic and antioxidant system, cell membrane integrity and MCs production/release progressively collapsed in the BPM system, finally the MCs rapidly detoxified to a safe level. The floating BPM system maintained excellent stability and efficiency over 165 h of water flushing, demonstrating its superior applicability. The global feasibility assessments of the BPM system based on real-world solar radiation further demonstrated its scalability for reducing HABs areas. This work provides both mechanistic insights and practical validation for sustainable water purification in HABs management.