Thesis (Ph.D)--Civil and Environmental Engineering, Georgia Institute of Technology, 2009. / Committee Co-Chair: Huang, Ching-Hua; Committee Co-Chair: Kim, Jae-Hong; Committee Member: Li, Qilin; Committee Member: Mulholland, James; Committee Member: Wine, Paul; Committee Member: Yiacoumi, Sotira. Part of the SMARTech Electronic Thesis and Dissertation Collection.

published_or_final_version / Environmental Management / Master / Master of Science in Environmental Management

Thesis (MTech (Chemistry))--Cape Peninsula University of Technology, 2017. / Pharmaceuticals have found extensive application in human health management. They are released into the environment through urine, excreta and inappropriate disposal methods. Residues of pharmaceutical products have been reported to show toxic consequences in some freshwater and marine organisms. Antibiotics are one of the most important groups of common human pharmaceuticals widely in use as prescribed and non-prescribed drugs. Antibiotics and their metabolites have been quantitated in water and found in trace levels. But even at such low concentrations they can maintain high biological activities with potential adverse effects on humans and animals. Unfortunately, many pharmaceutical compounds are resistant to breakdown in the environment, hence they have tendency for environmental magnification, since they are designed to be biologically active. Therefore, there is need to evaluate their environmental levels and their possible abatement methods using simple, cheap and low cost techniques, in order to avert their potential toxic consequences. In this research, a cost effective, robust, selective and rugged method for the analysis of antibiotics in water samples using liquid chromatography was developed, and used for monitoring levels of the selected antibiotics in Diep River. Also, an effective remediation procedure for these contaminants in water was developed using activated carbon produced from grape slurry waste.

published_or_final_version / Civil Engineering / Doctoral / Doctor of Philosophy

No description available.

Antibiotics are a group of compounds used in large quantities for both human therapy and animal food production. In recent years, antibiotics have been detected at low levels (up to μg/L) in wastewater effluents and surface waters in the US, Canada, and parts of Europe. The presence of such contaminants in the environment is of concern due to their potential to promote bacterial resistance as well as to trigger long-term adverse human health effects. Chemical disinfection, one of essential water treatment processes, may aid in their removal but may also form byproducts that can remain biologically active. Nanofiltration is another water treatment process that may provide an effective physical barrier for these contaminants. The goal of this study was to understand the effect chlorination and nanofiltration processes have on the fate of select antibiotics during water treatment, especially under varying water quality conditions. Changes in pH were found to significantly influence the reaction rate of one veterinary antibiotic, carbadox, with aqueous chlorine while also influencing the byproducts formed. The pH was also found to significantly alter the removal efficiency of several antibiotics by different nanofiltration membranes of varying pore size in which dependence was mechanistically investigated using transport models. In addition, the presence of tertiary amines was found to enhance transformation of antibiotics during chlorination. Overall, fundamental understanding regarding their fate during such water treatment processes will help industries develop better strategies for effectively controlling this emerging group of contaminants.

Use of antibiotics in the aquaculture industry for the control of bacterial infections in salmon has led to public concern regarding antibiotic residues in salmon tissue and the potential health risk this poses to humans. Oxytetracycline and Romet-30 are two common antibacterial agents utilized to control disease in the local finfish aquaculture industry of British Columbia, Canada. Many fish farms in British Columbia are located within close proximity to existing shellfish stocks. The potential for antibiotic bioconcentration and the production of bacterial resistance to the drugs in bivalves is a concern. The development of a solid phase extraction technique for these two drugs from Pacific oysters, Crassostrea gigas was accomplished. Analysis of whole oysters via HPLC revealed detectable levels of oxytetracycline and Romet-30 up to 4 weeks after antibiotic treatment at the salmon farm site. Oysters suspended in the salmon net pens and surrounding waters were sampled over a 5 month period. Concentration of oxytetracycline residues in oyster tissue reached a maximum of 0.11 ppm (n=2). Levels of sulphadimethoxine in oyster tissue reached a maximum concentration of 1.27 ppm (n=2). Maximum detectable concentrations of ormetoprim in oysters were 0.26 ppm (n=2). A controlled study investigating uptake and depuration of oxytetracycline and Romet-30 in the Pacific oyster revealed results similar to those described for the salmon farm. A flow through drug delivery system for the Pacific oyster was utilized over a ten day uptake and thirty day depuration period. Levels of oxytetracycline in whole animal tissue increased in a linear fashion (r²=0.984) over the uptake period. This indicates that the drug was bioaccumulated in the oyster reaching a maximum concentration of 10.72 ± 2.4 s.e. ppm (n= 3) on day 10 of uptake. Depuration of the drug was rapid. After thirteen days a concentration of 0.21 ± 0.04 s.e. ppm (n=7) was detected. The detection of Romet-30 in the uptake and depuration in the oyster was more erratic. Day 7 of uptake revealed a maximum concentration of sulphadimethoxine and ormetoprim of 1.092 ± 0.24 s.e. ppm (n=7) and 0.21 ppm (n=3) respectively. Depuration of Romet-30 was rapid. The concentration decreased to 0.029 ppm (n=3) by day 13. Condition indices of oysters sampled before and after antibiotic treatment indicated a significant increase (p<0.05) in condition index after treatment with medicated feed. A quantitative survey of bacteria associated with the gut of the oyster was performed. Relative numbers of endogenous bacteria were compared to oysters before and after antibiotic treatment. Numbers of bacteria significantly decreased (p< 0.05) following treatment. / Land and Food Systems, Faculty of / Graduate

The use of veterinary drugs continues to be a challenge since some farmers use drugs for medicinal purposes, while others use them as growth promoters without observing the set withdrawal times. In emerging economies, challenges are experienced in residue testing to ensure residue free animal products. It is therefore necessary to develop a simple, environmentally friendly and cost effective extraction method for veterinary drugs residues. A dispersive liquid-liquid micro-extraction method for simultaneous determination of chloramphenicol, florfenicol and thiamphenicol residues in water, bovine muscle and milk was developed optimised and validated. Analysis was performed with liquid chromatography coupled to electron spray ionization tandem mass spectrometry in negative ion multiple reaction monitoring mode. Dispersive liquid-liquid micro-extraction method development involved optimisation of parameters such as type and volume of extraction solvent, type and volume of disperser solvent and pH. The optimum extraction solvent was dichloromethane at a volume of 250 μL while the optimum disperser solvent was acetonitrile (1 mL) Extraction was found to be optimum at pH 7. The developed method was validated according to Commission decision 2002/657/EC. Linearity. Linearity was observed for water, bovine milk and muscle in the ranges of 0.3 μg kg-1 to 0.9 μg kg-1, 25 μg kg-1 to 100 μg kg-1 and 50 μg kg-1 to 200 μg kg-1 for chloramphenicol, thiamphenicol and florfenicol respectively with regression coefficients ranging between 0.9941 and 0.9999. Limit of detections for CAP, FFC & THAP were 0.082, 3.31, and 2.21 μg kg-1 respectively while Limit of quantifications were 0.163, 7.51 and 6.84 μg kg-1 respectively. The recoveries for water, bovine milk and bovine muscle ranged between 87.2% and 102%. In this study the validated dispersive liquid-liquid micro-extraction has been found to perform very well not only in the water matrix but also in the more complex matrices like bovine milk and muscle. / Chemistry / M. Sc. (Chemistry)