Modeling the fate of emerging contaminants and investigating the importance of their physical, chemical, and biological properties in water and wastewater treatment.

摘要

There is a growing concern about the potential risks to human health and aquatic life because of trace amounts of emerging contaminants, also called micropollutants (MPs), found in water and wastewater worldwide. These emerging contaminants encompass a large assortment of compounds (such as, pharmaceuticals, hormones, plasticizers, antiseptics, and antibiotics, etc.) and occur in very low concentrations, on the order of parts per billion to parts per trillion. Even at low concentrations, these micropollutants have been shown to cause certain deleterious effects on aquatic life (such as feminization of fish) and can be potentially harmful to human health (such as having endocrine disrupting effects). It has been shown that wastewater treatment plants (WWTPs) are the main source of micropollutants discharged into the environment and efforts have been employed to quantify the concentration of these micropollutants by sampling the influents and effluents of WWTPs. Although the toxic effects of these micropollutants in water are not well known, it is in the public's interest to study and understand the occurrence and behavior of these compounds, and the steps that Utilities can take to increase their removal efficiencies in drinking water and wastewater treatment plants.;Wastewater and drinking water treatment plants were not originally designed nor equipped to remove the trace amounts of these emerging contaminants. Each treatment plant utilizes different unit processes (all of which have a range of characteristics), has varied wastewater characteristics, and is exposed is a wide variety of emerging contaminants. Generalizing the removal efficiency of emerging contaminants proves nearly impossible; the removal efficiency of emerging contaminants from each treatment plant can be approximated from occurrence data, which is very crude as well as site specific. An integrated computer model for simulating wastewater and drinking water unit processes (with an emphasis on wastewater treatment) was developed to model the behavior of micropollutants. The parameters and characteristics of various micropollutants in water and wastewater treatment systems are discussed in this thesis, allowing a thorough investigation into the way in which MPs behave in these processes. This model places a strong emphasis on utilizing the chemical and physical properties of each compound in predicting its removal. The model aims to elucidate the removal of micropollutants by coupling their physical/chemical properties with the treatment plant operation characteristics. Furthermore, this thesis focuses on the study of the engineering controls of each unit process of various treatment plants (such as solids retention time, allowable influent and effluent concentrations, sludge wasting concentrations, microbial (biomass) concentrations allowed in the system, additional aerobic treatment, etc.) in order to maximize the removal efficiencies of a wide variety of emerging contaminants.