Novel electrode system for electroflotation of wastewater.

Electroflotation (EF) is an attractive method in wastewater treatment. The heart of EF is the dimensionally stable oxygen evolution anode that is usually expensive. In this paper, we present a stable anode by coating IrOx-Sb2O5-SnO2 onto titanium. Accelerated life test showed that the electrochemical stability of the Ti/IrOx-Sb2O5-SnO2 anode containing only 2.5 mol % of IrOx nominally in the activated coating was even higher than that of the conventional Ti/IrOx anode. Its service life for electroflotation application is predicted to be about 20 yr. Voltammetric investigation demonstrated that the Ti/IrOx-Sb2O5-SnO2 anode could provide fast electron transfer. Moreover, the present anode was designed to be fork-like and arranged interlockingly at the same level as the cathode with a similar shape. Such an innovation in electrode configuration and arrangement allows bubbles produced at both electrodes to be dispersed into wastewater flow quickly and, therefore, enhances the effective contact between bubbles and particles, favorable for high flotation efficiency. In addition, the novel electrode system reduces the interelectrode gap to 2 mm, a spacing that is technically difficult for a conventional electrode system. This small gap results in a significant energy saving. Easy maintenance is found to be another advantage of this novel electrode system.