Effective ultrasound electrochemical degradation of biological toxicity and refractory cephalosporin pharmaceutical wastewater

Biologically treated cephalosporin pharmaceutical wastewater is a complex industrial wastewater that is toxic and refractory for further biological treatment. For this purpose, a novel sonoelectrochemical catalytic oxidation-driven process using a nanocoated electrode has been developed to treat such wastewater. In the process, the synergy and mechanism of the sonoelectrochemistry using ultrasound enhancement of the nanocoated electrode activity to treat the wastewater was studied. The nanocoated electrode generated more radicals than the traditional coated electrode did; in the presence of ultrasonic waves, the mass-transfer effects on the nanocoated electrode surface were enhanced, resulting in rapid diffusion of the generated hydroxyl radicals into the solution, and quickly reacted with organic pollutants. Compared with the traditional coated electrode, the effect of the nanocoated electrode used on the wastewater treatment process was more enhanced by ultrasound under the same conditions. The biotoxicity of the wastewater in the sonoelectrochemical catalytic oxidation process was monitored and shown as having first increased and then decreased. The optimum operating conditions resulted in a 94% removal efficiency for COD and consisted of a current of density 8 mA/cm(2) and an ultrasound frequency of 45 kHz. All of the results showed that the sonoelectrochemical catalytic oxidation-driven process was found to be a very efficient method for the treatment of non-biodegradable cephalosporin pharmaceutical wastewater. (C) 2015 Elsevier B.V. All rights reserved.