Degradation of diclofenac during sonolysis, ozonation and their simultaneous application

Diclofenac is a widely used anti-inflammatory non-steroidal drug that escapes conventional urban wastewater treatment trains because of its resistance to biodegradation. Therefore it is frequently found in treated effluents, lakes and rivers. It has been reported that diclofenac can exhibit adverse effects on aquatic organisms. Advanced oxidation processes like ozonation (O3) and sonolysis (US) can be employed for the removal of such recalcitrant compounds from water matrices. This study included the investigation of the efficiency of O3 and US and also of their combined application (US + O3) for the degradation and potential mineralization of diclofenac in a water matrix. Under the conditions applied, all three systems proved to be effective in inducing diclofenac oxidation, leading to 22% of mineralization for O3 and 36% for US after 40 min of treatment. The synergy observed in the combined schemes, mainly due to the effects of US in enhancing the O3 decomposition, led to higher mineralization (about 40%) for 40 min treatment, and to a significantly higher mineralization level for shorter treatment duration.