Management of cyanobacteria and cyanotoxins in drinking water: A comprehensive review on occurrence, toxicity, challenges and treatment approaches

The synergistic effects of increased anthropogenic activities and climate change have intensified the frequency of cyanobacterial blooms in surface water bodies. These blooms pose significant health risks to humans and animals due to the release of cyanotoxins into the water. Conventional drinking water treatment plants (DWTPs) are often ineffective in removing cyanobacterial cells due to challenges such as electrostatic repulsion, hydrophilicity, and buoyancy. While excessive pre-oxidation can remove cyanobacteria, it may cause cell lysis, increase cyanotoxin concentration, and surpass various regulatory guidelines, posing additional risks of forming disinfection by-products (DBPs). Moderate pre-oxidation presents a viable alternative by effectively removing intact cyanobacterial cells. This review comprehensively analyses the occurrence, toxicity, associated challenges faced by DWTPs, and treatment approaches for cyanobacteria. Various moderate pre-oxidation processes for enhancing coagulation efficiency while preserving cell integrity are systematically summarized and critically discussed. The review also highlights the importance of holistic multi-barrier approaches, including prevention, corrections measures and water intake management for managing cyanobacterial contamination in drinking water treatment. It underscores the need for intensive research to develop affordable and effective solutions to ensure sustainable and safe drinking water provision.