Electrochemical Removal of Microcystis Aeruginosa in a Fixed Bed Reactor

The removal of M. aeruginosa from natural waters has been investigated by using a fixed bed cell with 3-dimensional electrodes in continuous mode. Steady state values of chlorophyll-a pigment, contained in the microalgae, were obtained, as well as concentrations of oxidizing species in the outlet stream of the system. In particular, attention was paid to two key parameters, flow rate and current density, to determine their influence on the removal of microalgae and on the concentration. Experiments were performed in a plastic cylindrical single pass cell, filled with glass spheres, connected to a hydraulic circuit. Grids of Titanium, arranged in stacks in-series, were employed as electrodes packing. The grids of the cathode packing were coated with platinum, while the grids of the anode packing were coated with Ir/Ru mixed oxides. The effect of the operative parameters on the possible mechanism of removal, namely electric field and electro-generated oxidants was investigated. The results show that the removal of M. aeruguinosa may be related to the synergistic effect of electro-generated oxidants produced from the chloride ions and electric field, although the main mechanism is the killing by long life oxidants electro-generated at the anode surface.