Application of a combination of electrooxidation and ozonation as a sustainable wastewater treatment process

Traditional wastewater treatments involve the addition of chemicals or the use of microorganisms. However, the limitation in both the processes is sludge generation. The sludge management and final disposal could represent up to 50% of the total wastewater treatment plant cost. Therefore, the use of advanced oxidation processes (AOPs) could represent an interesting option for treating wastewater with less or without sludge production. The final goal of advanced oxidation processes is the complete degradation of the pollutants present in wastewater aiming at its complete mineralization. Electrooxidation use one of the cleanest reagents: the electrons. Since the electrons are used in the oxidation process, it becomes sustainable. It is considered a robust technology and is easy to use. Therefore, it has been used for a diversity of wastewater treatments. The main advantages of this technology over other conventional treatments are: the addition of chemicals is not required and this process is carried out at room temperature and atmospheric pressure. Ozone is a powerful oxidant produced in gas phase and a mass transfer occurs to aqueous solution by means of a diffuser. A main advantage of using ozonation is that it oxidizes organic compounds without producing residual sludge. However, when both electrooxidation and ozonation processes take place at the same time, a synergy occurs and the process reaction time is decreased. It implies that the ozone dosage and electricity consumption is also reduced. This review paper gives the application of a combination of electrooxidation and ozonation as a sustainable approach for treatment of different types of wastewaters.