Biology Theses and Dissertations
Permanent URI for this collectionhttp://hdl.handle.net/1903/2749
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Item Influence of Various Wastewater Treatment Processes on Concentrations of Anthropogenic Pollutants and Their Transformation Products(2018) Armstrong, Dana Lynne; Torrents, Alba; Marine-Estuarine-Environmental Sciences; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Whether the use be in household, industrial, medicinal, or agricultural situations, modern society relies heavily on the use of chemicals. Unsurprisingly, many of these compounds are washed down the drain and have been detected in the wastewater treatment system. Compounds such as pharmaceuticals and personal care products (PPCPs), flame retardants, surfactants, and plasticizers have all been consistently detected in samples collected from wastewater treatment plants (WWTPs). Wastewater treatment is not designed specifically to remove these pollutants so they are oftentimes released into the environment via the discharge of WWTP effluent to local water bodies or the land application of treated sludge, also known as biosolids. Once released into the environment, chemicals can influence environmental health due to toxicity, bioaccumulation, microbial resistance issues, etc. Additionally, when degradation of these chemicals during treatment does take place, they are often not fully mineralized, leading to concerns regarding the environmental effects of transformation products. This research focuses on the impact that individual treatment systems have on concentrations of the antimicrobials triclosan (TCS) and triclocarban (TCC), 4 phthalate plasticizers, and their transformation products. The primary compounds studied have been shown to possess endocrine disrupting capabilities and to be present in biosolids at high concentrations due to extensive use. Treatment systems studied included activated sludge, nitrification, anaerobic digestion, and Cambi Thermal Hydrolysis Process (CambiTHP) pretreatment. Experiments were carried out in-lab using bioreactors to simulate treatment in a controlled manner as well as on-site at local WWTPs. The final goal of this research was the development of an extraction/analytical method for the detection of 27 compounds of concern in wastewater solids samples. Experimental results indicate that aerobic, anaerobic, and physical treatment processes can have mixed impacts on compound degradation and transformation product formation.Item Temporal Trends of and Influence of Storage Methods on Concentrations of Perfluoroalkyl Substances in Limed Municipal Wastewater Biosolids(2014) Armstrong, Dana Lynne; Torrents, Alba; Marine-Estuarine-Environmental Sciences; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Perfluoroalkyl substances (PFASs) are a classification of anthropogenic chemicals used in a variety of consumer and industrial products. Compounds from two PFAS subgroups, perflurocarboxylic acids (PFCAs) and perfluorosulfonic acids (PFSAs) are known to be persistent and have been detected in environmental and biotic samples worldwide. While long-chain PFCAs and PFSAs have been in a phase-out process within the United States and some have been regulated in Europe, these compounds have continued to be produced in developing countries. The sustained use of PFCA and PFSA compounds in consumer products, as well as the ability of some PFASs to degrade into these compounds, has led to their presence in the wastewater treatment (WWT) process. This study analyzes archived limed biosolids from a municipal WWT plant for temporal trends of 8 PFCAs and 4 PFSAs over an eight year period. This study also compares storage methods to determine influence on PFCA concentrations.