Thesis (PH.D.) -- Syracuse University, 2004. / "Publication number AAT 3160395."

Thesis (Ph. D.)--Syracuse University, 2005. / "Publication number AAT 3193849."

Thesis (Ph.D.)--University of Illinois at Urbana-Champaign, 2006. / Source: Dissertation Abstracts International, Volume: 67-07, Section: B, page: 4029. Advisers: Vernon Snoeyink; Benito Marinas. Includes bibliographical references (leaves 100-105) Available on microfilm from Pro Quest Information and Learning.

<p> Low-cost air quality sensor systems have the potential to provide entirely new information about our air quality given (1) the increase in temporal and spatial resolution that they facilitate, (2) their capacity to utilize many different sensor types in a single system, and (3) their accessibility that enables citizens to measure air quality for themselves. However, there are still many challenges associated with sensor use, including issues of sensor performance quantification and a need for best practices to guide the use of this technology, particularly for community-based research. This thesis addresses these challenges. This thesis includes the quantification of volatile organic compound using sensors to provide methane and non-methane hydrocarbon concentration estimates in complex environments. To support the development of best practices, multiple deployments allowed for the exploration of questions related to the influence the building-scale variability of pollutants on sensor system siting, choices in sensor data processing, and field calibration procedures. Additionally, education and outreach work utilizing sensors and involving partnerships with local communities are described with the focus on resources and lessons that could support future community-based air quality research. </p><p> This thesis also demonstrated the potential for sensor data. For example, sensor estimates of methane levels from a network deployed in rural Colorado revealed trends similar to those noted by other researchers using high-quality instrumentation and methods. In another example, sensor estimates of methane and total non-methane hydrocarbons levels, analyzed along with other sensor signals (i.e., from carbon monoxide and carbon dioxide sensors), helped to identify distinct pollutant sources on a fine temporal and spatial scale in a South Los Angeles neighborhood. The results and conclusions of this work support the continued development of this technology with the goal of collecting preliminary and supplementary information that may contribute to improved public and environmental health.</p><p>

<p> This study was performed to investigate the effects of humid air on nitrogen oxide (NOx) and particulate matter (PM) emissions of a compressed natural gas (CNG) engine. A 50 horse-power, 4 cylinder, naturally aspirated CNG engine was used for this study at a research facility in the College of Engineering at California State University Long Beach. The experiments were carried out at different relative humidity levels of 30%, 45%, and 60% at different power outputs of 5 HP, 12.5 HP, 25 HP, and 37.5 HP. At each test condition, the NOx and PM emissions are collected and analyzed through a dilution tunnel, the Horiba gas analyzer, and a cyclone with Teflon air filters. For PM measurements, the Teflon filters are weighed using a micro-balance at University of California, Irvine&rsquo;s biology lab, in prior and after running the experiments. Results show a decrease in NOx emission up to 91 percent and increase in PM emission by 7.4 mg with the increase in intake air humidity level.</p><p>

<p> Local, national and regional water supplies needed for energy production, meet the irrigation demands, industrial and domestic usage have come under sever degradation hence decreased the piezo metric water table level in the groundwater resources which finally results in negative environmental impacts. Silver Creek basin (area 154.8 mile2 equals to approximately 400.930 km²) locates in southern part of Illinois State, is connected to highland lake (which has a huge impact in the area and specifically Highland City) with east fork tributary. In this research watershed modeled in a hydrological model called SWAT (Soil and Water Assessment Tool) which is an extension of ArcGIS software, then watershed area is divided into 75 sub watersheds. Different parameters and variables are considered for sensitivity analysis in order to figuring out the most sensitive parameters and their ranges for flow rate calibration within different hydrological response units (HRUs). The flow rate quantified at sub basin level with daily time intervals. The model inputs are precipitations and meteorological data such as Solar Radiation, Wind speed and direction, Temperature and Relative Humidity, then model was calibrated with two sets of real data for Troy and Freeburg Stations in the middle and pouring point of watershed respectively. The main object was to test the performance of SWAT and the feasibility of using this model as a simulator of flow rate at a watershed scale. Model calibration and uncertainty analysis performed with SUFI-2 (sequential Uncertainty Fitting) which is interfaced with SWAT applying iSWAT generic program.</p><p>

<p> Tools for predicting rain garden performance are limited, particularly for predicting seasonal performance. Changes in temperature cause changes in the viscosity of water, infiltration rates, and evapotranspiration rates. A variably-saturated soil model, HYDRUS-1D, was calibrated and validated using observed ponding depth and soil moisture data for the Philadelphia Zoo Rain Garden, owned and operated by the Philadelphia Water Department (PWD). Warm and cold seasons were simulated with typical meteorological data and temperature-adjusted saturated hydraulic conductivity values. Design-storm simulations confirmed that the rain garden is over-performing. Maximum capacity of the system was simulated by increasing the loading ratio until overtopping occurred or ponding remained longer than 24 hours. This study will demonstrate how modeling of an operational urban rain garden offers a realistic picture of performance and could be used as a tool for informing regulations and design. </p><p>

<p> Heavy duty on-road vehicles represent one of the largest sources of NO_x emissions and fuel consumption in North America. Heavy duty vehicles are predominantly fueled with diesel, with the recent interest in natural gas (NG) systems. As emissions and greenhouse gas regulations continue to tighten new opportunities for advanced fleet specific heavy duty vehicles are becoming available with improved fuel economy. NO_x emissions have dropped 90% for heavy duty vehicles with the recent 2010 certification limit. Additional NO_x reductions of another 90% are desired for the South Coast Air basin to meet its 2023 NO_x inventory requirements and the California optional low NO_x standard in 2015.</p><p> One of the difficulties in quantifying NO_x emissions at the levels proposed in this research (90% of the 2010 certification level ~ 0.02 g/bhp-hr) is the measurement methods are approaching their detection limit to sufficiently quantify NO_x emissions. Three upgraded NO_x measurement methods were considered which include a raw NO_x measurement integrated with real time exhaust flow, a real-time ambient correction approach, and a trace level ambient analyzer for accurate bag analysis. In summary the improved methods varied in their success where the raw sampling approach showed to be the most accurate and precise over the rage of conditions tested. </p><p> The ISL G NZ 8.9 liter NG engine met and exceeded the target NO_x emissions of 0.02 g/bhp-hr. This engine significantly reduced 97%&ndash;100% of NO_x emissions compared with previous ISL G 8.9 engines. The NO_x emissions decreased as the duty cycle was decreased which was the opposite trend for the diesel vehicles. It is expected NG vehicles could play a role in the reduction of the south coast NO_x inventory problem given their near zero emission factors demonstrated.</p>

Removal of specific contaminants from high ionic strength process residuals, such as concentrate from desalting membranes, may increase the number of alternatives for residual disposal, reuse, and/or resource recovery. In the case of disposal, treatment of these waste streams could expand the number of feasible options while potentially lessening the environmental impacts of the residuals. With regards to increasing utilization of resources, treatment of membrane concentrate prior to the use of crystallization processes such as those used for zero-liquid discharge might increase the overall efficiency of the recovery system as well as improve the quality of the recovered salts by removing seed crystal poisons and potentially toxic constituents. Alternatively, reduction of key constituents to an acceptable level may allow for the treated residuals to be used as irrigation water for salt tolerant plants, saline aquaculture (farming of brine shrimp or other salt water species), or for options not yet identified because of the developing nature of this problem. Finally, treatment of the concentrate may allow for some portion of the residuals stream to be incorporated back into the overall treatment process leading to higher treated water recoveries. This research explored removal of specific pollutants from simulated and real high-pressure membrane concentrates by treatment with ferric chloride or calcium oxide (lime). Ionic strength effects were important in terms of particle aggregation for ferric iron treatments; this phenomenon was reflected in better solid liquid separation at higher ionic strengths (> 0.2 M) than at 0.008 M. Decreasing pH by acid addition to near 6.5 prior to iron treatments generally improved arsenic uptake compared to uptake where pH was not adjusted (pH ∼ 8). Arsenic uptake by solids formed during lime softening increased linearly with increasing lime dose is matrices consisting of calcium only or calcium and magnesium. Based on the results presented in this study, it would seem that precipitation with calcium can be an important mechanism of arsenic removal. Ionic strength effects were not significant during lime softening tests because, unlike the case of in-situ iron precipitation, solids were already present due to the addition of lime as a Ca(OH)2 slurry. Removal of arsenic from full-scale concentrates spiked with arsenic was somewhat similar for lime softening and in-situ iron precipitation. Arsenic was detected by EDX analysis of the solids formed during iron precipitation in the presence of arsenic, however, background noise during analysis of lime softening solids did not allow for arsenic detection. Organic carbon removal from full-scale concentrates was much less than the removals observed for similar doses during treatment of the simulated residuals. Predictions of arsenic removal from the full-scale concentrates (with and without arsenic spike) was relatively good, although more extensive modeling is required and better model parameters should be determined. Based on the economic evaluation of the treatment options for arsenic removal from full-scale residuals, iron coagulation with pH adjustment was cheaper than iron coagulation without pH adjustment option or lime softening for all three full-scale membrane concentrates (with and without arsenic spike).

Microwave chemistry has expanded over the last two decades due to the enhanced reaction rates achieved for many processes, including organic synthesis, inorganic synthesis and polymerization. Significant time and energy saving can be realized using microwave chemistry, which is important both commercially and for the environment. One of the most exciting and commercially/technologically significant areas where microwave energy has been demonstrated to influence the kinetics and selectivity is in the synthesis of nanoporous materials, such as zeolites. New nanoporous materials can be created, and the times for their syntheses can be significantly reduced, involving using less energy. By reducing the times by up to over an order of magnitude, continuous production would be possible to replace batch synthesis. However, the mechanism and engineering for the enhanced rates of these syntheses are unknown. The results from different laboratories are not consistent, and experimental details are sparse. Therefore, more research is required to unlock the mystery behind this “gee-wiz” chemistry. Furthermore, understanding the fundamental processes leading to rate enhancement by microwaves will also enable the optimization of these microwave heated reactions. In this work, the formation of SAPO-11 (and AlPO-11), silicalite and NaY zeolites under microwave heating was investigated and the influence of various microwave reactor engineering parameters was studied. Microwaves enhanced the SAPO-11 synthesis by two orders of magnitude over the conventional synthesis. Both nucleation and growth steps were enhanced by the presence of microwaves. Fast microwave heating was not solely responsible for this enhancement. This indicates that non-thermal interactions of material with microwaves are present for this synthesis. Many microwave reactor engineering parameters were identified as possibly influencing the microwave synthesis of SAPO-11 (and AlPO-11). These factors are precursor volume, reaction temperature, reactor size, stirring, applicator type and microwave frequency. Among those, the reaction temperature had the greatest influence on this SAPO-11 (and AlPO-11) synthesis. Increasing the reaction temperature decreased the nucleation time and increased the growth rate. The crystallization growth rate in the microwave synthesis showed higher activation energy (1.5 times) compared to the conventional synthesis. However, the pre-exponential factor increased by 8 orders of magnitude in the microwave synthesis. Nucleation rate also showed an increase in the activation energy (3.6 times) and an increase in the pre-exponential factor (10 orders of magnitude) by using microwave heating. This substantial increase in the pre-exponential factor could be the reason behind this microwave synthesis enhancement. High temperature, stirred synthesis, large vessel and using multimode field distribution oven found to be the optimum reaction conditions for microwave synthesis of SAPO-11 (and AlPO-11). Thermal variations within SAPO-11, silicalite and NaY synthesis solutions were measured using a reaction vessel with multiple fiberoptic temperature probes. NaY synthesis solution has the shortest microwave penetration depth among these zeolite synthesis solutions which led to great thermal variations between the region near the wall (high temperature) and the center (low temperature) when placed in a vessel with diameter 20 times larger than its penetration depth. Increasing these thermal variations led to a decrease in the nucleation time and thus enhanced this NaY microwave synthesis. Microwave power delivery mode (pulsed vs. continuous) effect on the synthesis of the three zeolites mentioned above was investigated. Pulsing the microwave power required less average power to maintain the synthesis reaction temperature compared to continuous delivery mode. No effect of using pulsed compared to continuous microwave power delivery was found on the nucleation time and the crystal growth for these zeolite syntheses. However, pulsed microwave power delivery produced smaller particles in the case of SAPO-11. The effect of simultaneous cooling effect on the microwave synthesis of SAPO-11 and silicalite was studied. Increasing the amount of power delivered to the SAPO-11 synthesis while maintaining the reaction temperature fixed using the simultaneous cooling, decreased the nucleation time and increased the growth rate. Smaller particles were formed at high power. Silicalite showed no change in the nucleation time, crystal growth and/or the morphology. This indicates that there is no universal pattern among the microwave synthesis of zeolites. What could be an important factor for one synthesis is not necessarily important for another, and is likely dependant on the dielectric properties and the reaction mechanism. Key words: Zeolite, SAPO-11, silicalite, NaY, microwave synthesis, nucleation, crystal growth, frequency, reactor engineering, overheating, temperature distribution, pulsing power delivery, simultaneous cooling.