Investigation of determination methods and removal of antibiotics in wastewater

The objective of the present study was to determine the seasonal concentration of antibiotics, which are the most used medicine group in Turkey, in water treatment plants and to determine the removal rates at different stages. An indirect objective of the study was to develop methods of mass spectrophotometry to determine antibiotic concentrations. Furthermore, a laboratory-scale alternative process was developed for antibiotics that could not be completely removed in existing treatment plants. All chemicals that harm the pathogens are called antibiotics. Antibiotics are classified as betalactams, fluoroquinolones, macrolides, tetracyclines, sulphonamides, trimethoprims, and other antibiotics based on their chemical and structural properties. The clearance rate of non-metabolized antibiotics in the body varies between 10% and 90%. Thus, fecal or urinary antibiotics are discharged into sewage water and reach urban wastewater treatment plants. The knowledge on antibiotic removal performance of the conventional methods used in treatment of domestic wastewater and planning the plants based on removal yields is important, especially today when micropollutant removal is on the agenda. It is known that antibiotics are prescribed in 7 out of 10 prescriptions in Turkey and that the resistance of several bacterial species against antibiotics is very high in our country. Among all medicine consumption, antibiotics are the leading product group in Turkey for the last 6 years. Although there has been a lot of emphasis on high antibiotic consumption during recent years, comprehensive studies on determination of antibiotic concentrations in water matrix and the establishment of an analytical method for detection of antibiotics were unfortunately not conducted. The aim of the present thesis is to fill this gap in the national literature in Turkey. In the study conducted within the scope of this thesis, the most commonly consumed antibiotics in Turkey were determined based on sales volumes and it was concluded that the study should be conducted on 6 different groups. Antibiotics were determined in samples obtained at the treatment facility that operates at two different levels in Istanbul province and at a university hospital wastewater, and removal efficiency was investigated in treatment facilities. Chromatographic method was developed for the analysis of 6 different antibiotic groups. In the other study section, the removal of the related antibiotics with nanofiltration membranes was investigated on synthetic and real wastewater. Antibiotic concentrations were monitored seasonally for 1 year on University of Istanbul, Çapa Faculty of Medicine sewage system and 24-hour composite samples were obtained from Paşaköy Advanced Biological Wastewater Treatment Facility influent and effluent, Tuzla Advanced Biological Wastewater Treatment Facility influent, biological treatment effluent and advanced biological treatment effluent and the antibiotic concentrations were monitored seasonally for one and a half years and antibiotic removal in treatment plants was identified. Antibiotic removal highly differentiated based on antibiotic concentrations and wastewater operation processes, and it was observed that all antibiotics in the beta lactam group and tetracycline were generally 100% removed in the treatment facilities. It was determined that the removal rates for clarithromycin, lincomycin, levofloxacin, ciprofloxacin, trimethoprim antibiotics were quite low in the existing treatment plants. Thus, as a result of 1 and a half year monitoring study, the removal of the active agents of the fluoroquinolone, lincosamide, macrolide and trimethoprim group antibiotics, which were unlikely to be removed in biological treatment plants, from synthetic solutions prepared with 250 μg /L and 1000 μg /L ultrapure water was studied using five different nanofiltration (NF) membranes (NFCK, NFDK, ESNA, NF90, NF270). In the studies conducted with synthetic and real wastewater, it was found that nanofiltration membranes can effectively remove antibiotics that could not be removed in the treatment facility. In conclusion, application of NF process on treatment facility effluent seems to be an optimal solution today to prevent the antibiotic induced damages to the microorganisms in the receiving environment that could not be removed with conventional treatment methods and to reduce the amount of antibiotics in the antibiotic cycle that indirectly reaches to humans. Keywords: Antibiotics, conventional treatment, advanced treatment, SPE, LC-MS/MS, nano-filtration, wastewater