Ultraviolet–C radiation for sustainable control of harmful algal blooms and aquatic weeds

Aquatic ecosystems are increasingly threatened by invasive aquatic weeds and harmful algal blooms (HABs), driven by eutrophication, climate change and anthropogenic disturbances. These proliferations degrade water quality, disrupt ecosystem functioning, reduce biodiversity and cause major economic losses in fisheries and water management. Conventional control strategies, including chemical, mechanical and biological methods, often provide limited effectiveness and may generate secondary environmental impacts. Ultraviolet–C (UV-C) radiation has emerged as a promising non-chemical alternative for sustainable aquatic ecosystem management. This review evaluates the mechanisms underlying UV-C mediated control of aquatic weeds and HABs, including DNA photodamage, reactive oxygen species generation, photosynthetic inhibition and membrane disruption. This processes collectively suppress cellular growth and viability. Recent advances in UV-C technologies, such as UV-light-emitting diode (UV-LED) systems, mobile treatment platforms and advanced oxidation processes [UV/hydrogen peroxide (UV/H₂O₂), UV/ozone (UV/O₃) and UV/peroxymonosulfate (UV/PMS)], have enhanced treatment efficiency for algal suppression, cyanotoxin degradation and pollutant removal. Treatment efficiency is strongly dose-dependent, with higher UV-C fluence generally resulting in greater microbial inactivation, algal suppression and cyanotoxin degradation. The review further examines field applications, engineering considerations and the integration of UV-C with smart monitoring tools including artificial intelligence, remote sensing and autonomous systems for precision aquatic management. However, treatment efficacy remains strongly influenced by turbidity, dissolved organic matter, water depth and species-specific tolerance, while challenges related to energy demand, operational cost and ecological impacts on non-target organisms persist. Future research should focus on optimising low-energy and solar-assisted UV systems, improving reactor design and integrating UV-C into ecosystem-based management frameworks. Overall, UV-C radiation offers a versatile and environmentally compatible strategy for sustainable control of aquatic weeds and HABs.