Emerging and Combined Electrochemical Methods

Electrochemical water treatment methods offer ways to find more sustainable solutions for water treatment applications. The majority of electrochemical water treatment methods use electricity as the main reactant to conduct the treatment process. Among well-developed electrochemical water treatment methods such as electrocoagulation, electroflotation, electrodialysis, electrochemical oxidation, and reduction, there are emerging methods, which show good prerequisites for their use in industrial scale applications. These methods tend to increase further removal rates of pollutants, eliminate drawbacks, and extend the applicability of existing electrochemical water treatment methods as well as improve cost-efficiency. The following emerging and combined electrochemical methods will be discussed in this chapter: electrodeionization, capacitive deionization, electro-Fenton, microbial fuel cell treatment, photo- and sonoelectrocatalyses. Electrodeionization combines two desalination processes into one, which are electrodialysis and ion exchange, and as a result provides even deeper demineralization rates. Capacitive deionization is an energy-efficient method allowing simultaneous water desalination and recuperation of electric energy. Electro-Fenton allows in situ generation of catalysts, thus reducing the sludge formation. Microbial fuel cells, along with the water treatment, allow recovery of electrical energy, thus reducing maintenance cost required for this method. Photoelectrocatalysis provides better removal efficiencies compared to singular photocatalysis because of the enhanced charge carrier separation and suppression of electron-hole recombination in electric field. Sonoelectrocatalysis improves the mass transfer of reactive species, inhibits polarization of electrodes, and contributes to hydroxyl radical generation, thereby enhancing the efficiency of the treatment comparing to the singular electrochemical oxidation.