Plasticizers are widely used as additives for the production of PVC and other types of plastics. They have been observed to leach out of the solid matrix over the course of the lifetime of the finished product. These compounds have now been observed across the globe and in different environments. The main focus of this work is the study of the interactions of industrial plasticizers with soil microorganisms including bacteria, yeast and fungi. / This research is concerned with the microbial degradation of plasticizers such as di-2-ethylhexyl phthalate (DEHP) and di-2-ethylhexyl adipate (DEHA). In particular, the study has focused on the stable metabolites produced during biodegradation, including 2-ethylhexanol and 2-ethylhexanoic acid. The first step was to show that these toxic metabolites were found in significant concentrations in the environment. In addition, a series of experiments with a variety of organisms showed how wide spread the ability to produce these metabolites was. Most organisms tested were capable of interacting with the plasticizers and many of these produced the metabolites. / It was apparent that these metabolites could have appreciable stability and an in-depth study with one species of bacteria, R.rhodochrous , showed that the entire initial 2-ethylhexanol component incorporated in the original plasticizers could be accounted for. Some of this was volatile and found in the exit gas of the reactor. This included all of the 2-ethylhexanol and some of the 2-ethylhexanol. These compounds may contribute to the impairment of the quality of indoor air. An overall mass balance showed that while the bacterium could eventually oxidize the 2-ethylhexanol released by hydrolysis to 2-ethylhexanoic acid, it could not degrade this acid. Thus, a summation of the quantities of each of the various metabolites generated equaled the original amount of 2-ethylhexanol in the plasticizer. / A mathematical model was then constructed to include all of the above features of the interaction of R.rhodochrous with the plasticizers DEHA and DEHP. This model included terms for the biological interactions and enzyme kinetics as well as the toxicity and inhibition of bacterial growth by the plasticizers and their metabolites. The increased understanding of the interaction of microbes with plasticizers will lead to a better understanding of the environmental impact of these compounds and their metabolites. The results of this study also demonstrate that when assessing the environmental impact of a compound, it is essential that not only should the impact of the parent compound be considered, but it is essential that the assessment process must also account for impacts associated with degradation products.

Mushroom tyrosinase (polyphenol oxidase, EC 1.14.18.1) was investigated as an alternative to peroxidase, enzymes for the catalytic removal of phenolic compounds from wastewaters. The maximum catalytic activity was observed at pH 7; however, significant activity was observed at pHs ranging from 5 to 8. Tyrosinase was unstable under acidic conditions and at elevated temperatures. The activation energy for thermal inactivation of tyrosinase was determined to be 1.85 kJ mol-1 at pH 7. The transformation of phenols catalysed, by tyrosinase was investigated as a function of pH, initial phenol concentration, and additives. Phenol was transformed successfully with tyrosinase, over a wide range of pH (pH 5--8) and a wide range of initial concentrations (0.5 mM--10 mM). Some chlorinated phenols were also successfully transformed with tyrosinase. Polyethylene glycol and chitosan did not improve the transformation efficiency of phenol. However, chitosan was successfully used to remove coloured, products resulting from treatment Since coagulation with aluminium sulfate failed, the colour removal induced by chitosan addition appeared to be the result of simultaneous coagulation and adsorption mechanisms. Minimum doses of chitosan required to achieve 90% of colour removal were logarithmically related to the quantity of phenol treated. All solutions of phenol and chlorophenols treated with tyrosinase, had substantially lower toxicities, than their corresponding initial toxicities. Chitosan addition enhanced the reduction in toxicity very effectively. The toxicities of the phenol solutions treated with tyrosinase were markedly lower than previously reported toxicities of solutions treated with peroxidase enzymes.

Soybean peroxidase (SBP) was investigated as an alternative to horseradish peroxidase (HRP) in the catalytic removal of phenolic compounds from wastewaters. The catalytic activity of SBP depended on reaction pH and hydrogen peroxide concentration. A pseudo steady state kinetic model describing the dependence of activity on peroxide concentration was derived and apparent kinetic constants describing the oxidation of SBP by hydrogen peroxide and the reduction of SBP by phenol were determined. SBP incubated at 25$ sp circ$C was relatively stable in neutral and alkaline buffer but was inactivated in acidic buffer. SBP incubated at elevated temperatures experienced 1st order thermal inactivation that depended on incubation temperature and pH. At 25$ sp circ$C in pH 7.4 buffer, SBP incubated with hydrogen peroxide demonstrated biphasic suicide inactivation whose rate depended on the initial peroxide concentration. SBP catalyzed removal of seven phenolic compounds from aqueous solution depended on enzyme dose, reaction pH and buffer species, the phenolic compound, and the measurement technique used to quantify removals. While the observed ability of SBP to catalyze phenolic compound removal was less efficient than the reported ability of HRP, the industrial grade cost of SBP is sufficiently less than the cost of HRP that SBP can be considered an attractive alternative to HRP in the treatment of wastewaters containing phenolic compounds.

<p> The scale of the climate crisis is immense and solutions are urgently needed. This dissertation develops tools to provide highly tailored carbon footprint information and place-based solutions to U.S. households and communities in three complimentary studies. The first study quantifies the greenhouse gas (GHG) savings potential of different U.S. metropolitan areas and household types within locations, developing average household carbon footprint (HCF) profiles for 28 metropolitan areas, 6 household sizes and 12 income brackets. The model includes emissions embodied in transportation, energy, water, waste, food, goods, and services, and further quantifies GHG and financial savings from potential mitigation actions across all locations and household types. The size and composition of carbon footprints vary dramatically between geographic regions (38 to 52 tCO₂e) and within regions based on basic demographic characteristics (&lt;20 to >80 tCO₂e). Despite these differences, large cash-positive carbon footprint reductions are evident across all household types and locations. </p><p> Using national household surveys, the second study develops econometric models to estimate HCF for essentially all U.S. zip codes, cities, counties, and metropolitan areas. The results demonstrate consistently lower HCF in urban core cities (&sim;40 tCO₂e) and higher carbon footprints in outlying suburbs (&sim;50 tCO₂e), with a range from &sim;25 to >80 tCO₂e in the 50 largest metropolitan areas. In contrast to a vast literature demonstrating GHG savings in more dense cities, analysis of all U.S. locations presents a more complex picture. Population density exhibits a weak but positive correlation with HCF until a density threshold is met, after which range, mean, and standard deviation of HCF decline. While population density contributes to relatively low HCF in the central cities of large metropolitan areas, the more extensive suburbanization in these regions contributes to an overall net increase in HCF compared to smaller metropolitan areas. Suburbs alone account for &sim;50% of total U.S. HCF. </p><p> Results from this quantitative research have informed the development of "smart" online carbon management tools that allow users to quickly calculate, compare and manage household carbon footprints, and to visualize average community carbon footprints using high spatial resolution interactive maps. Yet, the potential benefits of such tools are limited to those who find them, and the information may often do little to increase intrinsic motivation to adopt new low carbon technologies and practices. Following lessons from behavioral sciences, a subsequent study engaged &sim;2,700 residents in eight participating cities to track and reduce household carbon footprints and compete for the title of "Coolest California City." The yearlong pilot project achieved an estimated 14% reduction in electricity consumption, lending evidence that community-scale climate initiatives, enabled by sophisticated information and communication technologies and motivated local program implementers, can help scale up tailored, place-based climate solutions. Together, this research and accompanying tools and programs provide a framework for individuals and communities to prioritize GHG mitigation opportunities and stimulate collective climate action.</p>

<p> Ordered mesoporous carbon (OMC) materials have attracted great interests from NASA due to their remarkable properties, such as high specific surface area, regular and tunable pore size. These features show great potential for being used in the water recovery system (WRS) in the International Space Station (ISS) as potential adsorbents. Various methods have been explored on the OMC preparation and modification to achieve better adsorption results. In this research, acrylic acid was used as a carbon precursor to synthesize OMC using a common silica mesoporous template (SBA-15). The influence of silica template amount was tested by using different ratios of SBA-15 to acrylic acid. The modification processes were conducted by immersing methods using four different aqueous solutions: 30% ammonium hydroxide, 0.1% sodium hydroxide, 1 mol/L aluminum chloride, and 0.02 g/mL urea solution. BET-SSA, FT-IR, TEM, TGA, and XRD were used to characterize the structures of OMCs and modified OMCs. It demonstrated that all the products had well-ordered hexagonal structure. The modifying procedures had eroded the surface of the OMC, but the highly ordered structures had been preserved based on the TEM and XRD results. FT-IR analysis indicated that the functional groups were introduced to the surface of the modified OMCs, which affected the adsorption capacity significantly. Resorcinol, a typical total organic carbon (TOC) model compound, was selected to evaluate the adsorption behavior of the OMCs and modified OMCs. Adsorption study illustrates that OMC produced by 3:1 ratio of SBA-15 to acrylic acid showed a higher adsorption capacity than that of OMCs produced with other ratios. The ammonium hydroxide modified OMC had the highest adsorption capacity of 40.6 mg/g for resorcinol removal, compared with that of the other three modified OMCs.</p>

<p> This dissertation presents the development and application of a computational model called BioChemFOAM developed using the computation fluid dynamic software OpenFOAM (Open source Field Operation And Manipulation). BioChemFOAM is a three dimensional incompressible unsteady-flow model that is coupled with a water-quality model via the Reynolds Average Navier-Stokes (RANS) equations. BioChemFOAM was developed to model nutrient dynamics in inland riverine aquatic ecosystems. BioChemFOAM solves the RANS equations for the hydrodynamics with an available library in OpenFOAM and implements a new library to include coupled systems of species transport equations with reactions. Simulation of the flow and multicomponent reactive transport are studied in detail for fundamental numerical experiments as well as for a real application in a backwater area of the Mississippi River. BioChemFOAM is a robust model that enables the flexible parameterization of processes for the nitrogen cycle. The processes studied include the following main components: algae, organic carbon, phosphorus, nitrogen, and dissolved oxygen. In particular, the research presented has three phases. The first phase involves the identification of the common processes that influence the nitrogen removal. The second phase covers the development and validation of the model that uses common parameterization to simulate the main features of an aquatic ecosystem. The main processes considered in the model and implemented in BioChemFOAM are: fully resolved hydraulic parameters (velocity and pressure), temperature variation, light's influence on the ecosystem, nutrients dynamics, algae growth and death, advection and diffusion of species, and isotropic turbulence (using a two-equation k-epsilon model). The final phase covers the application and analysis of the model and is divided in two sub stages: 1) a qualitative comparison of the main processes involved in the model (validation with the exact solution of different components of the model under different degrees of complexity) and 2) the quantification of main processes affecting nitrate removal in a backwater floodplain lake (Round Lake) in Pool 8 of the Mississippi River near La Crosse, WI. </p><p> The BioChemFOAM model was able to reproduce different levels of complexity in an aquatic ecosystem and expose several main features that may help understand nutrient dynamics. The validation process with fabricated numerical experiments, discussed in Chapter 4, not only presents a detailed evaluation of the equations and processes but also introduces a step-by-step method of validating the model, given a level of complexity and parameterization when modeling nutrient dynamics in aquatic ecosystems. The study cases maintain fixed coefficients and characteristic values of the concentration in order to compare the influences that increasing or decreasing complexity has on the model, BioChemFOAM. Chapter 4, which focuses on model validation with numerical experiments, demonstrates that, with characteristic concentration and coefficients, some processes do not greatly influence the nutrient dynamics for algae. </p><p> Chapters 5 and 6 discuss how BioChemFOAM was subsequently applied to an actual field case in the Mississippi River to show the model's ability to reproduce real world conditions when nitrate samples are available and other concentrations are used from typical monitored values. The model was able to reproduce the main processes affecting nutrient dynamics in the proposed scenarios and for previous studies in the literature. First, the model was adapted to simulate one species, nitrate, and its concentration was comparable to measured data. Second, the model was tested under different initial conditions. The model shows independence on initial conditions when reaching a steady mass flow rate for nitrate. Finally, a sensitivity analysis was performed using all eleven species in the model. The sensitivity takes as its basis the influence of processes on nitrate fate and transport and it defines eight scenarios. It was found in the present parameterization that green algae as modeled does not have a significant influence on improving nitrate spatial distributions and percentage of nitrate removal (PNR). On the other hand, reaction rates for denitrification at the bed and nitrification in the water shows an important influence on the nitrate spatial distribution and the PNR. One physical solution, from the broad range of scenarios defined in the sensitivity analysis, was selected as most closely reproducing the backwater natural system. The selection was based on published values of the percentage of nitrate removal (PNR), nitrate spatial concentrations, total nitrogen spatial concentrations and mass loading rate balances. The scenario identified as a physically valid solution has a reaction rate of nitrification and denitrification at the bed of 2.37x10^-5 s^-1. The PNR was found to be 39% when reaching a steady solution for the species transport. The denitrification at the bed process was about 6.7% of the input nitrate mass loading rate and the nitrification was about 7.7% of the input nitrate mass loading rate. </p><p> The present research and model development highlight the need for additional detailed field measurements to reduce the uncertainty of common processes included in advanced models (see Chapter 2 for a review of models and Chapter 3 for the proposed model). The application presented in Chapter 6 utilizes only spatial variations of nitrate and total nitrogen to validate the model, which limits the validation of the remaining species. Despite the fact that some species are not known a priori, numerical experiments serve as a guide that helps explain how the aquatic ecosystem responds under different initial and boundary conditions. In addition, the PNR curves presented in this research were useful when defining realistic removal rates in a backwater area. BioChemFOAM's ability to formulate scenarios under different driving forces makes the model invaluable in terms of understanding the potential connections between species concentration and flow variables. In general, the case study presents trends in spatial and temporal distributions of non-sampled species that were comparable to measured data.</p>

<p> Two US Forest Service draft monitoring protocols are used to assess the effectiveness of design channels at road-stream crossings by comparing their physical channel dimensions to those in the natural channel. Level II physical monitoring is a time intensive, quantitative and statistically based procedure for assessing effectiveness at selected sites. Level I physical monitoring is a less detailed, rapid procedure limited to a few simple measurements and observations for assessing effectiveness at a large number of sites. Study objectives were to: 1) test and refine the field methods for collecting data by the levels I and II physical monitoring protocols; 2) find a meaningful way to combine the data collected by levels I and II into separate effectiveness evaluations by each protocol; and, 3) evaluate whether the level I protocol can be used as a proxy for the level II protocol. Where the two protocols systematically differ, field data help distinguish why. </p><p> Study results for all objectives (combined) include: improved field methodologies, recommendations for further development, and separate summary rubrics for the levels I and II monitoring protocols. The recommendations are of three categories; channel metrics/data collection, methods of scoring each metric, and sample sizes. Some of most significant of those recommendations are described within the following paragraphs. </p><p> Data collection methods might be improved to save time, increase the accuracy of protocol evaluations, and facilitate agreement between the levels I and II protocol evaluation results. The techniques by which the level I bankfull stage and coarse fraction of the gradation metrics are collected should incorporate level II methods. Instructions for collecting level II coarse fraction of the gradation data should specify measuring all particles within the channel, including particles much larger than the sampling frame. The level I method by which the representative reach is selected should incorporate a basic longitudinal profile survey in which only the most prominent grade controls separating slope segments are captured. Decreasing the allowable gradient difference between the level II design channel and representative reach might also improve accuracy. The method by which the levels I and II protocols compare channel units (or channel unit sequences) between the design and representative reach should be equivalent, as should the rules by which slope segments and channel units are defined. Finally, the channel metrics of low flow width and bed irregularity are inconsistent with the objectives of physical effectiveness monitoring, in that they are aspects of habitat, rather than strong controls on channel form. I suggest they be eliminated from the levels I and II protocols. </p><p> The level II summary rubric scores most metrics statistically by a Wilcoxon Rank-Sum test of medians. For most metrics, the Wilcoxon Rank-Sum test appears to be a reasonable way to compare representative reach and design zone data. For the metrics of bed and bank irregularity, however, a test of distributions (e.g., Kolmogorov-Smirnov) is recommended instead. The coarse fraction of the gradation metric would be more fairly assessed if the modes of the particle size (in phi units) were compared instead of the medians. Doing so would allow the design and representative reach gradients to be slightly different (as does the criteria for selecting a representative reach) without penalizing the metric score. </p><p> The levels I and II summary rubric tools created were used to evaluate twelve AOP road-stream crossing designs. The performance of the levels I and II summary rubrics were then assessed by the evaluation results at those twelve sites. Levels I and II generally seemed to provide effectiveness evaluations which agreed with site observations, data, and photographs. Further, the summary rubrics facilitated concurrent evaluation of the many channel dimensions which together affect the hydraulic conditions experienced by aquatic organisms. In addition, the simple utility of the levels I and II summary rubric tools should encourage effectiveness monitoring and help restoration practitioners learn from their mistakes, ultimately improving aquatic organism passage design methods and results. (Abstract shortened by UMI.)</p>

<p> In at least 45 low- and middle-income countries, piped water systems deliver water for limited durations. Few data are available of the impact of intermittent water supply (IWS) on the water quality and quantity delivered to households. This thesis examines the impact of intermittently supplied piped water on the quality and quantity of water delivered to residential taps in Hubli-Dharwad, India, when compared to continuous piped water supply. A framework for understanding the pathways through which IWS can impact water quality is first developed. The extent to which contamination occurs in Hubli-Dharwad is quantified by comparing microbial water quality throughout the distribution system in an intermittent system and a continuous system in the same city. The mechanisms affecting water quality in the IWS network in Hubli-Dharwad are identified by measuring changes in water quality over time using continuous measurements from pressure and physico-chemical sensors paired with grab samples tested for indicator bacteria. In the final chapter, a new method of measuring household water consumption in an IWS when supply durations are limited and few metered data are available is developed. This thesis showed that the intermittent supply was frequently subject to contamination in the distribution system and that households with intermittent supply consumed limited quantities of water. While these results demonstrated that converting to a continuous water supply can improve water quality when compared to intermittent supply, this conversion may not be possible in the near future for resource-constrained towns and cities. This thesis contributes to knowledge of the mechanisms causing contamination and constricting water access in IWS systems, which can help improve systems to ensure that people with piped water receive water that is reliable, safe, and sufficient.</p>

<p> This dissertation describes the design, development, and field validation of a concentrator photovoltaic (CPV) solar energy system. The challenges of creating a highly efficient yet low-cost system architecture come from many sources. The solid-state physics of photovoltaic devices present fundamental limits to photoelectron conversion efficiency, while the electrical and thermal characteristics of widely available materials limit the design arena. Furthermore, the need for high solar spectral throughput, evenly concentrated sunlight, and tolerance to off-axis pointing places strict illumination requirements on the optical design. To be commercially viable, the cost associated with all components must be minimized so that when taken together, the absolute installed cost of the system in kWh is lower than any other solar energy method, and competitive with fossil fuel power generation. </p><p> The work detailed herein focuses specifically on unique optical design and illumination concepts discovered when developing a viable commercial CPV system. By designing from the ground up with the fundamental physics of photovoltaic devices and the required system tolerances in mind, a select range of optical designs are determined and modeled. Component cost analysis, assembly effort, and development time frame further influence design choices to arrive at a final optical system design. </p><p> When coupled with the collecting mirror, the final optical hardware unit placed at the focus generates more than 800W, yet is small and lightweight enough to hold in your hand. After fabrication and installation, the completed system's illumination, spectral, and thermal performance is validated with on-sun operational testing.</p>

The hydraulic behavior and mixing processes in wastewater basins are studied experimentally in a laboratory scale model. The laboratory basin is modeled after a full scale aerated lagoon system operating in Saint-Julie, Quebec. Three experimental techniques are used to reach the objectives: (i) video flow visualization, (ii) tracer studies and (iii) two-dimensional flow measurements using hot-film anemometry. Experiments are conducted on non-aerated basins, as well as on artificially aerated basins. / The flow visualization and flow measurements show that the hydraulic behavior of non-aerated wastewater basins is very complex, due to the formation of flow patterns such as stagnant zones and recirculation. The location and size of these flow patterns are determined using the measured velocity flow field and the flow visualization images. Mixing in these basins is highly non-uniform since flow is clearly segregated into high-velocity and low-velocity areas. The exchange between these areas is very low, affecting the distribution of solids and contaminants. / When artificial aeration is introduced, mixing becomes more uniform. Flow measurements and visualization indicate that the size of stagnant zones and the extent of recirculation decreases. The tracer studies show that, in general, aeration tends to decrease the actual residence time of the waste material. Calculation of the dispersion number, d, and the dead volume, Vd, are not sufficient to characterize the effect of aeration on mixing. / The understanding of mixing and transport mechanisms in wastewater basins is important, because such basins are often used in applications which require settling or mixing of solids and contaminants.