Nowadays, both developed and developing countries are suffering from water scarcity due to the rapid urbanization and global climate change. The on-site reuse of water is a possible solution, which calls for the development of various decentralized wastewater treatment techniques. Electrochemical oxidation is a promising candidate due to its modular design, convenient operation, and small carbon footprint. In the past decades, the IrOx based DSA® electrode showed excellent performance on saline wastewater treatment. However, the high cost and low energy efficiency impede the widespread application. In this study, uniform TiO2 thin film was deposited onto the IrOx electrode by novel spray-pyrolysis process. Instead of acting as catalyst, the IrOx interlayer is served as ohmic contact to facilitate the electron transfer from TiO2 top layer to the bottom Ti metal plate. Hence the required loading is significantly decreased. Interfacial electrochemical reaction in saline water can be manipulated by this approach. The pristine IrOx electrode is active for both oxygen and chlorine evolution. After TiO2 deposition, chlorine evolution prevails. Further increasing the thickness of TiO2 film or inducing SnO2 dopant provide additional active sites for the generation of stronger oxidants such as Cl● and Cl2●-. The optimized TiO2/IrOx electrodes were integrated into the solar-powered electrochemical reactor to treat black water. Rapid COD and total nitrogen removal as well as disinfection can be achieved after 4 hr with energy cost of 100-200 kWh/kg COD. Phosphate, Ca2+, and Mg2+ can be simultaneously removed in the form of cathodic precipitate. The treated water meets the criteria for water reuse.

Multi-layer anode for saline wastewater treatment: Manipulating oxidant generation pathway by TiO2 thin film deposition

251st National Meeting (2016)

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