Toxic cyanobacteria threaten drinking water safety, and pre-oxidation process can enhance the removal of cyanobacteria and cyanotoxin in drinking water treatment plants. Cyanobacterial blooms were a successive bloom, including development, maintenance and decline stage, which were driven by the life cycle of cyanobacteria. In our previous studies, we found that the change of life cycle strongly affected pre-chlorination, and it is not feasible to treat low-viability cyanobacteria at decay stage. Compared with chlorination, low-dosage potassium permanganate can maintain membrane integrity of cyanobacteria. Thus, we further evaluated potassium permanganate to remove cyanobacteria and cyanotoxin at different stages.
Results showed that potassium permanganate can promote coagulation removal of low-viability cyanobacteria, and extracellular cyanotoxin and algal organic matters were also reduced. In addition, different response pattern of cyanobacteria at development and maintenance stage to potassium permanganate was observed. For example, elevated cyanobacterial biomass decreased toxin degradation efficiency for maintenance stage. We proposed that practical strategy of potassium permanganate treatments should be adopted depending on the stage of cyanobacteria.
This study revealed the influences of life cycle of cyanobacteria on pre-oxidation process by potassium permanganate, and proved that potassium permanganate could be a promising pre-oxidant to treat low-viability cyanobacteria. These findings can provide an important guideline of potassium permanganate to treat cyanobacteria-laden waters during a successive bloom.
The results published in recent Water Res. (10.1016/j.watres.2021.117353) and J. Hazard. Mater. (10.1016/j.jhazmat.2021.126492). Dr. Xi Li was the first author, and Professor Xin Yu, was the corresponding author. This work was supported by Science and Technology Project of Water Resources Department of Fujian Province, China (MSK201711), Science and Technology Major Project of Xiamen, China (3502Z20171003).
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