Influence of Various Wastewater Treatment Processes on Concentrations of Anthropogenic Pollutants and Their Transformation Products

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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.