The widespread use of antibiotics has been causing increase of their extent in the environment. Antibiotics are not completely metabolised in the body. Most antibiotics come into the environment through animals, as they are used in the veterinary medicine for health prevention, for the treatment of bacterial infections, with the purpose to promote growth and/or animal increment. The rest come to the environment because of human consumption, due to the treatment of bacterial infections. Antibiotics into the environment directly affect the aquatic organisms, and above all, the increasing concern arouses phenomenon of resistant bacteria or superbacteria. These bacteria are resistant to antibiotics and, consequently, they are not affected by them, so nowadays more and more bacterial infections are more difficult to be cured or are even incurable.
Therefore, the removal of antibiotics is necessary. Due to the entry of most antibiotics in the aquatic environment, their removal from wastewater is the most important. Conventional municipal wastewater treatment plants are not capable of removing antibiotics and thus they can easily enter surface water, groundwater, and even drinking water. The main focus nowadays is the addition of the tertiary cleaning using advanced oxidation processes.
The purpose of this thesis was to compare the various advanced oxidation processes for wastewater treatment containing antibiotics and verification if these procedures are suitable for the removal of antibiotics from the aquatic environment. We studied the following experimental techniques/procedures: direct ozonation, ozonation at elevated pH (pH = 9.5), ozonation at elevated pH (pH = 9.5) at the addition of H2O2, catalysed ozonation by addition of Fe2+, catalysed ozonation by addition of Fe2+ and UV light, ozonation with Fenton oxidation and ozonation with photo-Fenton oxidation. The methods were evaluated according to the total organic carbon (TOC) and chemical oxygen demand (COD).
It can be concluded that studied procedures occur in two phases with first stage of process to be more effective. Direct ozonation was the least effective in terms of TOC, as well as COD. The efficiency of the ozonation increased at elevated pH, with the addition of UV, H2O2 and/or catalysts. The most effective procedure was ozonation with photo-Fenton oxidation, where we achieved between 83 and 96% oxidation of the present antibiotics and between 65 and 84% mineralization, hence the complete decomposition of antibiotics into inorganic components, CO2, and H2O. Our results confirmed that advanced oxidation processes are appropriate for removing antibiotics from wastewater.
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