Assessing Removal of Pharmaceutical Compounds in Conventional Wastewater Treatment and Ultraviolet-Peracetic Acid Advanced Oxidation Process and Development of a Comprehensive Analytical Method for the Quantification of Veterinary Antimicrobials Spanning Several Livestock Industries
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Pharmaceuticals and personal care products (PPCPs) are contaminants of emerging concern. Two main pathways for PPCPs to enter into the environment is through the discharge of municipal wastewater into receiving water bodies, and through land application of manure from animals that receive antimicrobials, especially food-producing animals in confined feeding operations (CAFOs). Liquid chromatography tandem mass spectrometry (LC-MS/MS) provides an accurate and sensitive analytical method for multiresidue detection in environmental samples. In an effort to understand the loading of pharmaceutical residues into the environment, this research was conducted with two specific goals: (1) To assess the fate of 42 pharmaceuticals in a conventional municipal wastewater treatment plant and evaluate pharmaceutical removal with the implementation of an emerging advanced oxidation procedure utilizing peracetic acid and UV irradiation, and (2) To develop a comprehensive analytical method for the detection of several antimicrobial classes relevant to livestock industries. The work done in chapter 2 assessed the occurrence of 42 pharmaceutical compounds in wastewater and their removal by each treatment unit in a conventional activated sludge system. In this research, the effectiveness of an advanced oxidation procedure (AOP) utilizing UV/peracetic acid (PAA) in removing pharmaceuticals from wastewater was also investigated. Of the 42 compounds monitored, 21 were consistently detected in wastewater, which included 7 antibiotics, 8 antidepressants, and 6 other types of drugs (analgesics, non-steroidal anti-inflammatory drugs, anticonvulsants, antipsychotics, and stimulants). From the two weekly sampling events of conventional treatment, only 6 pharmaceuticals were removed in both weeks. Additionally, seventeen out of the 21 pharmaceuticals were detected in the activated sludge, with experimental sorption coefficients ranging from 5.6 "×" 100 to 1.7 "×" 104 L/kg. UV/PAA treatment of tertiary effluents decreased the total concentrations of antibiotics and antidepressants by ~36% and ~20%, respectively, with PAA doses of 6 mg/L and a UV fluence of 1600 mJ/cm2. A few compounds known to be persistent in the conventional system were removed by UV/PAA, such as carbamazepine (22% removal), bupropion (47-59%), and citalopram (30%). However, in the more turbid secondary effluents, UV/PAA did not achieve significant pharmaceutical removal, suggesting that UV/PAA performance was severely suppressed by wastewater matrix. In chapter 3, an LC-MS/MS method was developed for the quantification of macrolides, ionophores and tiamulin in manure; all three antimicrobial classes are extensively used in livestock production in the United States (U.S.). There are three current LC-MS/MS methods in the Aga Laboratory that analyze for: (1) sulfonamides and tetracyclines, (2) macrolides, and (3) ionophores. In order to improve and decrease analysis time, the addition of ionophores, macrolides, and tiamulin to the sulfonamide and tetracycline method for the detection of 5 total antimicrobial classes was investigated. Various solid phase extraction (SPE) methods were investigated for the extraction of all 5 antimicrobial classes: (1) extraction using tandem amino-HLB cartridges, and (2) only HLB cartrdiges eluted with either 50/50 or 75/25 methanol/ethyl acetate. However, the strong sorption of the ionophores to the amino (NH2) SPE cartridges (used as an additional clean-up column for the extraction of sulfonamides and tetracyclines) resulted in poor recoveries (<31%). This likely occurred due to the chelation of metal cations by the ethylenediamine tetraacetic acid (EDTA) in the extraction buffer, as metal complexing is crucial for the ionophores’ ability to hydrophobically interact with the stationary phase. The recoveries of all analytes in the second SPE method were insufficient, ranging from 1.6-69% and 6.4-96% in the 50/50 and 75/25 elution mixtures, respectively. Complete evaporation of SPE eluate was determined as a potential source for analyte loss in the cleanup and extraction process. Further studies need to be done in order to develop an optimized extraction method for macrolides, ionophores and tiamulin.