Blue algae blooms could cause the indiscriminate killing of fish/invertebrates in water and the destruction of the local ecological equilibrium. The release of cyanotoxins by blue algae cells could kill livestock and cause various health problems to human beings. The highly effective photocatalytic disinfection of Anabaena sp. PCC 7120 as a representative blue algae specie under visible light illumination was demonstrated on a visible-light-activated palladium oxide-modified nitrogen-doped titanium oxide (TiON/PdO) nanoparticle photocatalyst. The large release of substances in blue algae cells, such as chlorophyll a and various ions, and severe damages on their cell wall/membrane clearly demonstrated the photocatalytic disinfection on blue algae by TiON/PdO nanoparticles under visible light illumination was an irreversible process. TiON/PdO nanoparticles also demonstrated a highly efficient photocatalytic degradation of a typical cyanotoxin, Microcystin LR, under visible light illumination. Thus, the photocatalytic treatment by TiON/PdO nanoparticles could effectively disinfect blue algae and degrade cyanotoxins under visible light illumination at the same time, which makes it attractive as an environmentally friendly and cost-effective alternative to current blue algae treatment practices. (C) 2014 Elsevier B.V. All rights reserved.