Ozonation of NSAID: A Biodegradability and Toxicity Study

This work deals with the biodegradability and toxicity of three non-steroidal anti-inflammatory drugs (NSAID) (diclofenac, ibuprofen and naproxen) treated by ozonation. The results show that the total removal of 200 mg L-1 of diclofenac and 100 mg L-1 of naproxen is possible using an ozone dose of 0.20 and 0.04 g L-1, respectively. For 200 mg L-1 of ibuprofen, 90% removal is achieved using an ozone dose of 2.3 g L-1. The BOD5/COD ratio, the Zahn-Wallens test and EC50 toxicity test (Microtox) are chosen as biological and toxicity indicators of NSAID intermediates. The evolution of BOD5/COD ratio during 1 hour of treatment is evaluated and the results show that ozonation improves the biodegradability for the three NSAID treated solution. The Zahn-Wellens test for diclofenac and ibuprofen solutions shows that biological mineralization, after 28 days, is higher for diclofenac than for ibuprofen solution. According to the Microtox test, the treatment with ozone removes the toxicity of the naproxen solution. Taking into account the results obtained with the biocompatibility tests it could be assumed that ozonation is an adequate treatment for removal NSAID in aquatic medium, and the ozonated effluents could be post-treated in a biological wastewater facility.