Mitigation of cyanobacterial harmful algal blooms (cHABs) and cyanotoxins by electrochemical oxidation: from bench-scale study to field application

Cyanobacterial harmful algal blooms (cHABs) and the release of carcinogenic cyanotoxins have become a great threat to the recreational use of lakes and sources of drinking water. It is challenging for conventional water treatment techniques to mitigate cHABs events that occur massively and irregularly. Therefore, the development of emergency-responsive technology for point-of-use treatment is imperative. In this study, an electrochemical oxidation and filtration (EOF) process was developed that enables pump-and-treat of phytoplankton plumes and cyanotoxins. With the microporous filter anode as the key component, the novel technology features the effective production of oxidants (i.e., free chlorine, radicals, ozone) within the micropores of the anode by water electrolysis driven by direct current. Cyanobacteria and cyanotoxins will be readily inactivated and destroyed when passing through the pores. 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. Additionally, the concentration of disinfection byproducts generated by EOF was five times less than conventional homogeneous chlorination to achieve the same level of treatment. A boat-mount 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/d and energy consumption of 1.1 kWh/m3. To better deploy the EOF process to combat cHABs, ResET Water was founded to commercialize the technology from research to production phase. Through participating in the National Science Foundation's Innovation Corps course and conducting 103 cold call interviews, ResET Water was able to identify several potential customer segments for their technology and narrow in on a beachhead market. By reducing recreational downtime associated with cHABs by 90%, ResET Water's technology would provide significant value to the lake associations and other organizations.