Recent Achievements in Combination of Ultrasonolysis and Other Advanced Oxidation Processes for Wastewater Treatment

A review of recent advancements in the combination of ultrasonolysis with other advanced oxidation processes is studied. This study is based on the recent achievements and developments in the field of water and wastewater treatment using ultrasonic irradiation by means of acoustic cavitation with other advanced oxidation technologies. The most important parameter in combined methods is the synergetic effect which is a variable relative to the type of contaminant(s) and other physicochemical properties. The synergetic effect has the key role in process intensification so that a higher synergetic effect provides a higher intensified process efficiency. Results showed that sonolysis is a method that can increase the synergetic percentage in lowering fixed and even operating cost of the wastewater remediation. The combination of photolysis, photocatalysis, Fenton, photo-Fenton, and ozonation processes with ultrasonolysis results in hydroxyl radical production and therefore, the degradation of the organic chemicals. The effect of various parameters on the efficiency of combined processes is investigated in the present study. The combined process performance and the synergetic effect depend on the operating conditions and wastewater characteristics. The synergetic effect can enhance the degradation of organic compounds up to 400%. For example, it has been proven that the sonophotocatalytic process shows over 80% improvement with respect to the photocatalysis alone.