Treatment of Toxic Algal Blooms By Electrochemical Oxidation

The frequent occurrence of cyanobacterial harmful algal blooms (cHABs) poses serious threats to freshwater habitats and drinking water sources due to the impairment of the ecosystem and the production of macrocystis. This research targets cHABs using electrochemical oxidation (EO) to lyse cyanobacteria and destruct microcystin (MC)-LR. The novel EO process features the Ni, Sb codoped SnO₂ (NATO) anode that can produce ozone and chlorine by water electrolysis. Experiments conducted on Synechococcus, model cyanobacteria, show the dominant contribution of ozone, as an oxidizer, in destructing cyanobacteria. The optimized lab-scale EO treatment destroyed more than 99% of Chl-a in 90 seconds at a current density of 10 mA/cm². Lab results suggest that the EO process is independent of the chloride concentrations. Comparing the EO process to the conventional ozonation, EO inactivated cyanobacteria at faster kinetics yet required less ozone dose. The lab-scale mechanistic study is in line with our field test results obtained from a large-scale EO system to treat cHAM-impacted lake water at a capacity of 300 m³/d. The EOF treatment process developed by this study demonstrates an efficient and scalable solution to address the cHABs challenges in freshwater.