Occurence, Fate and remediation of veterinary antibiotics in surface waters

Tzelepi, Evangelia and Halsall, Crispin (2024) Occurence, Fate and remediation of veterinary antibiotics in surface waters. PhD thesis, Lancaster University.

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Abstract

Pollution from pharmaceuticals in the aquatic environment is now recognized as an environmental concern in many countries. There has been an increasing concern in recent years about the occurrence, fate, and adverse effects of pharmaceutical residues in the aquatic environment. Some of the most widely and frequently used drug classes are antibiotics as they can be used both in humans and animals. Pharmaceuticals end up in soil, surface waters and eventually in ground water, which can be used as a source of drinking water, after their excretion (in unmetabolized form or as active metabolites) from humans or animals via urine or faeces. The possible routes of antibiotics once they get into the aquatic environment are mainly three either they mineralise to carbon dioxide, sorb into the soil and sediment or for ends up in receiving waters (surface and ground water. A fast and simple method for the analysis of 15 commonly used antibiotics in water samples deriving from a catchment area was developed. The method combines online solid phase extraction using a reusable online trapping column combined with analytical separation on a C18 analytical column and detection by a signle quadrupole mass spectrometer. The method was fully validated for detection and quantification limits as well as linearity, repeatability, and matrix effects. The method gave an excellent linear response (r2 > 0.99) and detection limits for all compounds (1–50 ng L−1) The method was used to monitor diffuse pollution from farm and WwTWs in a rural area. Most of the antibiotics were detected in the samples, except from cephalosporins, with maximum concentrations measure for sulfamethoxazole at 1659 ng L-1 at the discharge point of WWTP. Once released into the aquatic environment, pharmaceuticals may undergo different degradation processes. Photodegradation is an important route of elimination for light-sensitive pharmaceuticals, such as antibiotics. In this study, the fate of two sulphonamides, one tetracycline and one fluoroquinolone was investigated in different matrices to establish possible degradation patterns. A comparison between laboratory acquired photolysis data and field data was made that identified an increasing need for more routine field work. Degradation under natural sunlight for more photosensitive compounds appeared in line with the laboratory results however there were big discrepancies between the laboratory obtained values and the ones derived from the outdoor experiment for the more persistent compounds. Recently, microalgae based technology has been explored as a potential alternative for the treatment of wastewater containing antibiotics by adsorption, accumulation, biodegradation, photodegradation, and hydrolysis. In this role a primitive study was conducted to evaluate the removal rates and degradation of two sulphonamides in the presence of naturally grown algae. Both of compounds exhibited faster degradation in the presence of algal species. After a 5 day incubation period up to 79% of sulfadiazine and 68% of sulfamethoxazole were removed by algae mediated photolysis against 56% and 28% when compared to photolysis alone by using clean media.