Mitigation of Cyanobacterial Harmful Algal Blooms (chabs) and Cyanotoxins by Electrochemical Oxidation: from a Bench-Scale Study to Field Application

ABSTRACT: Cyanobacterial harmful algal blooms (cHABs) and the concurrent release of cyanotoxins have become an emerging threat to aquatic life and drinking water safety. It is challenging for conventional frequently and irregularly. This study developed an emergencyresponsive electrochemical oxidation and filtration (EOF) process that enables the pump-and-treat of phytoplankton plumes and cyanotoxins. Fundamental studies indicate that the EOF process generated locally concentrated free chlorine (>16 times higher than the bulk chlorine concentration) at the porous Ti4O7 filter anode surface. Lab tests showed that cyanobacteria and the cyanotoxin microcystinLR were inactivated and destroyed by free chlorine when passing through the porous anode. Additionally, the concentration of disinfection byproducts generated by EOF was five times less than chlorination to achieve the same level of treatment. A boatmount full-scale EOF system was developed and deployed in Lake Neatahwanta impacted by cHAB. The system can effectively remove >50% of phytoplankton and >80% of the ambient cyanotoxins at a treatment capacity of 110 m3/day and energy consumption of 1.1 kWh/m3. Instant improvement of effluent water clarity was achieved.