UNS: Class-Specific Transformations of Antibiotics in UV-Based Water/Wastewater Treatment Processes

University Of Maryland Baltimore County, Baltimore MD

Investigators

Abstract

1510420 Blaney The proposed work focuses on ultraviolet-based transformation reactions for three classes of antibiotics: fluoroquinolones, tetracyclines, and sulfonamides. The blockbuster drugs (e.g., ciprofloxacin, tetracycline, sulfamethoxazole) in these classes have been extensively studied; however, the behavior of these compounds during ultraviolet -driven water/wastewater treatment processes does not necessarily extend to other compounds within the same class. Furthermore, a potential for antibiotic transformation into other antibiotics exists. The overall objective of this project is to provide a comprehensive understanding of ultraviolet-based reactions of 40 compounds from three critical antibiotic classes. The project will include antibiotics of concern including 15 fluoroquinolones, 10 tetracyclines, and 15 sulfonamides. The hypothesis is that a significant potential for antibiotic-to-antibiotic transformation exists during ultraviolet -based processes. This avenue for antibiotic generation during water/wastewater treatment is critical to lowering the risks associated with antibiotic concentrations in finished water and wastewater effluent. This hypothesis will be tested by the following Specific Aims: 1. To develop an online solid-phase extraction liquid chromatography electrospray ionization tandem mass spectrometry analytical method for 40 antibiotics. 2. To measure reaction kinetics and antibiotic transformation with ultraviolet light at 253.7 nm and hydroxyl radicals in synthetic solutions, finished water, and wastewater effluent. 3. To identify antibiotic-to-antibiotic transformations within each class and construct reaction pathways to demonstrate potential for residual antimicrobial activity after ultraviolet treatment. 4. To characterize the residual antimicrobial activity of treated solutions (i.e., synthetic, drinking water, and wastewater) containing ultraviolet transformation products. The approach is a multi-pronged research strategy which will increase understanding of the fate of an increasingly important class of chemicals in water and wastewater. Awareness of antibiotic-to-antibiotic transformations within specific classes has been confined to natural systems, not engineered ultraviolet processes. The proposed study represents transformative research that challenges conventional wisdom surrounding transformation of antibiotics in ultraviolet processes. Another transformative quality of this project derives from the emphasis on a class-based approach to study of pharmaceutical and personal care products, rather than a large investigation of chemically-diverse molecules. The expected benefits of the proposed research include measurement of specific molar absorptivity, quantum yield, and fluence-based pseudo-first order rate constants; determination of second-order rate constants for antibiotic reaction with hydroxyl radicals; identification of phototransformation products/pathways for antibiotics; and characterization of the toxicity of transformation products. To better understand the impact of the national prescription drug take-back day program on preventing pharmaceuticals from entering the aquatic environment, the PI will be working with a DEA Special Agent to gather quantitative data on future collections. In particular, the PI proposes identifying and massing all prescription drugs deposited at the UMBC and Howard County Police Departments each year.