Algae removal and degradation of microcystins by UV-C system: A review

Harmful algal blooms (HABs), driven by eutrophication, are a growing ecological threat, compromising water quality and ecosystem health through the release of toxic microcystins (MCs). These toxins pose significant risks to both aquatic life and human health. Among the emerging solutions, UV-C technology has gained attention for its efficiency in inhibiting algal growth and degrading MCs, offering a cost-effective and environmentally friendly approach with minimal secondary pollution. However, existing studies often overlook key aspects, including the variability in algae sensitivity to UV-C wavelengths, the stability of treatment across diverse aquatic conditions, and the toxicity of degradation byproducts. This review highlights the mechanisms underlying UV-C-based algae removal, explores its potential limitation, such as algal resistance, and compares its efficacy with other remediation methods. Notably, the lack of comprehensive research on wavelength-specific sensitivity and real-world application efficacy represents a significant knowledge gap. Further investigation into these areas is essential to optimize UV-C technology for mitigating HABs and improving water safety in eutrophic environments. PRACTITIONER POINTS: The choice of UV band should be adjusted to the algae species. The UV-C system, with limited studies and applications in natural water bodies, demonstrates instability. Combining UV-C with other technologies substantially enhances the efficiency of algal control. Future research should emphasize strategies to prevent the rapid release of microcystins (MCs) from this system due to cell lysis and extracellular release within a short time frame.