Control of cyanobacterial bloom and purification of bloom-laden water by sequential electro-oxidation and electro-oxidation-coagulation

Abstract

The outbreaks of cyanobacterial blooms have caused severe threat to aquatic ecosystem and public health. In this work, electrochemical technology with RuO₂/IrO₂/Ti (RIT) or/and Al as anode for cyanobacterial bloom control and simultaneous water purification were studied. Compared with RIT-Al and Al electrodes, RIT exhibited the highest effects on bloom algae inactivation and inhibition of algae regrowth. Live/dead analysis, SEM, intracellular reactive oxygen species (ROS) and antioxidant system activities revealed that RIT could disintegrate bloom flocs and damage embedded algal cells due to high intensity of oxidation. With the lysis of cyanobacterial bloom, high content of intracellular compounds containing organic carbon, nitrogen and phosphorus released, necessitating water quality restoration. In the subsequent water purification process, RIT-Al overtook RIT and Al in removal of organic and nutrient pollutants due to the complex effects of electro-oxidation, coagulation, co-precipitation, electro-nitrification and electro-denitrification. Therefore, sequential electro-oxidation and electro-oxidation-coagulation process was an effective method for control cyanobacteria bloom and simultaneous removal of DOM, microcystin-LR (MC-LR), nitrogen and phosphorus, which is a promising technology.

Keywords: Bloom flocs disintegration; Cyanobacterial bloom control; Electro-coagulation; Electro-nitrification and electro-denitrification; Electro-oxidation.