Removal of emerging pharmaceuticals from wastewater by ozone-based advanced oxidation processes

This study investigates the use of ozone as a pretreatment process for water containing pharmaceuticals. Experiments were carried out on synthetic wastewater, surface water, and the effluent of wastewater treatment plant. The degradation efficiencies of four groups of pharmaceuticals (antibiotics, estrogens, acidic, and neutral) were studied, and the effect of ozone dose and pH on the degradation efficiency was monitored. A MicrotoxTM bioassay test was used to evaluate the change in the toxicity of aqueous solutions before and after ozonation. The efficiency of oxidation of antibiotics, estrogens, and neutral pharmaceuticals increased as the ozone dose and pH increased. Ozone input dose of 188.1, 222.3, and 222.4 mg h21was found to be optimum yielding the highest oxidation efficiency for the studied pharmaceuticals in synthetic wastewater, surface water and effluent of wastewater treatment plant, respectively. An average specific ozone dose of 2.05 for antibiotics, 1.11 for estrogens, and 1.30 mg O3/mg DOC for neutral pharmaceuticals reduced significantly the acute the toxicity of the water solutions and mineralized more than 40%, 33%, and 23% of DOC in less than 1 min. The kinetics of ozone with pharmaceuticals was modeled for synthetic wastewater as an overall second-order reaction with a rate constant ranging from 103 to 106 M21 s21. The results indicate the effectiveness of ozone-based advanced oxidation processes in removing emerging pharmaceuticals from water and wastewater. The results showed that ozonation process is more effective than other conventional oxidation processes (Cl2 and ClO2) in eliminating pharmaceuticals and reducing the toxicity of the effluent water or wastewater.