Efficient Inactivation and Removal of a Harmful Marine Algae—Heterosigma akashiwo—By UV-Assisted Permanganate Oxidation

Abstract

Harmful algal blooms (HABs) caused by Heterosigma akashiwo are occurring in coastal waters frequently, posing a great risk to marine environments and subsequent treatment processes like desalination. UV-assisted permanganate oxidation (UV/KMnO4) is recognized as an innovative advanced oxidation process. This study investigated the inactivation and removal efficiencies of H. akashiwo cells by UV/KMnO4. Algal cells were effectively disintegrated into fragments by UV/KMnO4. Also, the degradation of photosynthetic pigments, membrane lipid peroxidation, and severe oxidative stress in algal cells was observed. The removal efficiency of algal cells reached 80.2% by 20 min of UV/KMnO4 oxidation, with a KMnO4 dosage of 5 mg L−1. In addition, the residual algal cells could be completely removed by a subsequent self-settling process, without an additional coagulation procedure. The fragmentation of algal cells caused by UV/KMnO4 may facilitate the formation of algal flocs, thereby improving the cell settleability. Furthermore, UV254 was significantly reduced by UV/KMnO4, which is expected to reduce the formation of disinfection byproducts and membrane fouling. This study elucidates that UV/KMnO4 can be a promising technique for the efficient treatment of harmful marine algae.