Nowadays, there are more and more diseases and therefore more and more pharmaceutical drugs, including antibiotics. Their overuse (in human and veterinary medicine) and the inappropriate disposal of active pharmaceutical ingredients (in sewage systems, in the environement, etc.) have led to the development of resistant bacteria. As a result, pharmaceutical companies are developing more and more antibiotics and other active pharmaceutical ingredients.
The aim of our work was to assess the efficiency of ozonation-based processes for treatment of wastewaters containing antibiotics. For this purpose, a model wastewater using the antibiotic vancomycin was prepared and ozonated at different temperatures (room temperature –20 °C and elevated temperature –40 °C). Direct ozonation, ozonation at elevated pH, ozonation at elevated pH with the addition of hydrogen peroxide, catalytic ozonation, photo-catalytic ozonation, ozonation by Fenton oxidation and ozonation by photo-Fenton oxidation were carried out. The chemical oxygen demand (COD) and total organic carbon (TOC) of the samples were measured. From the results obtained, the treatment efficiency and the kinetics of degradation were calculated, as well as the activation energy according to the Arrhenius relation.
In order to determine the environmental impact of the treated wastewater, we carried out a toxicity test with Vibrio fischeri using luminescence-emitting marine bacteria. This test was used to determine the toxicity of treated and untreated wastewater to the environment.
We have found that a two-stage ozonation reaction takes place, with the first stage, which is more efficient, taking place more quickly. It is also more efficient and also faster at elevated temperature. We cannot confirm complete mineralisation of selected antibiotic with any type of ozonation, as the decomposition efficiencies are at a maximum of 94 %. Based on the TOC and COD analysis, ozonation at elevated pH with the addition of hydrogen peroxide and ozonation at elevated pH are the most successful. However, the toxicity test reveals that these two treatment processes resulted in the most toxic effluent, therefore we propose the use of direct ozonation as a solution, which may indeed be less effective, but is the least dangerous for the environment.
|
