The synergistic effect and mechanism of in-site algae inactivation in simulated ballast water by dimension-stable anode electrocatalysis

Abstract

The spread of harmful algae through ballast water poses serious threats to marine ecosystems, so the development of effective methods to inactivate the algae and to treat the harmful pollution in ballast water was important. Electrocatalysis technology is safe and reliable and has been widely used in water treatment. In this paper, a dimensionally stable anode (DSA) electrocatalysis system was studied to investigate the efficiency of in-site algae inactivation in simulated ballast water. The studies showed that the DSA electrocatalysis system showed good efficiency for algae inactivation in ballast water, and the inactivation rate varied depending on the algae and could be optimized by adjusting hydraulic retention time (HTR), current density, and electrode surface area. Furthermore, the DSA electrocatalysis provided a significantly sustained inactivation effect on algae in the holding time after electrolytic operation. The inactivation rate for Platymonas helgolandica and Heterosigma akashiwo reached 99.27% and 99.09%, respectively, in short treatment time (HRT of 60 s), and the energy consumption was 0.350 kWh/L and 2.654 kWh/L. Besides the direct oxidation and reduction of electric field, the reactive oxides generated in the DSA electrocatalysis process were the primary factors which caused algae inactivation. The total residual oxides (TRO) damaged algae cells and led to algae inactivation. The DSA electrocatalysis led to lipid peroxidation in algal cell membranes, causing structural damage and metabolic failure. The DSA electrocatalysis was an effective and clean technology for the in-site algae removal in ballast water.