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Title: Quantification of Methane Emissions via the Use of an Optical Remote Sensing Technique in a Landfill Setting.
Creator: Clark, Jeremy Matthew, Abichou, Tarek, Chanton, Jeff, Watts, Michael, Department of Civil and Environmental Engineering, Florida State University
Abstract/Description: The United States Environmental Protection Agency (USEPA) has proposed a method that will be used to quantify fugitive emissions from large area sources such as landfills. The method is presented in the USEPA's Other Test Method-10 (OTM-10) manual. The method utilizes non-intersecting multiple-beam paths, scanning equipment, and Optical Remote Sensing (ORS) instruments in a variety of radial configurations. The use of an ORS instrument to scan in a radial configuration introduces radial plume...
Show moreThe United States Environmental Protection Agency (USEPA) has proposed a method that will be used to quantify fugitive emissions from large area sources such as landfills. The method is presented in the USEPA's Other Test Method-10 (OTM-10) manual. The method utilizes non-intersecting multiple-beam paths, scanning equipment, and Optical Remote Sensing (ORS) instruments in a variety of radial configurations. The use of an ORS instrument to scan in a radial configuration introduces radial plume mapping (RPM) to the OTM-10. There are several RPM methods discussed in the OTM-10, such as horizontal radial plume mapping (HRPM), vertical radial plume mapping (VRPM), and 1-D radial plume mapping (1D-RPM). The VRPM is the only method discussed in the OTM-10 that is capable computing pollutant flow rates for a large area source such as a landfill, so this study looks into the reliability of the VRPM's ability to quantify methane emissions from a landfill setting. The VRPM is used as a tool to quantify pollutant concentrations measured in the vertical plane downwind from the emissions source. In conjunction with the concentration data, which is computed by the vertical plane, wind speed and direction data is monitored to convert pollutant concentration values to pollutant flow rates by multiplying the concentration data to a trigonometric function of the wind speed. The objective of this study was to investigate uncertainties associated with the use of the VRPM method in a landfill setting. Once deficiencies in the method are found, users of the VRPM in a landfill setting will be provided with accurate guidelines on the reliability of the method under a variety of conditions. Several uncertainties associated with the VRPM method in a landfill setting include; the location of hot spots in comparison to vertical plane location, the reliability of the of the optimization algorithm used in quantification to correctly compute emission concentration when multiple hot spots are present, and the area contributing to flux (ACF). Through this study it was found that the spatial variability of emissions in the emitting domain can lead to uncertainties of -34 to 190% in the measured flux value when idealistic scenarios were simulated. The level of uncertainty can be reduced by improving the vertical planes location in comparison to the hot spots. The variability in wind direction during VRPM testing can introduce an uncertainty of 20% of the measured flux value. This study also provides an estimate to the ACF for each meteorological stability class defined in the field and has an uncertainty of 10 to 30% associated with it.
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Date Issued: 2010
Identifier: FSU_migr_etd-3592
Format: Thesis

Title: Engineering Properties of Florida Concrete Mixes for Implementing the Aashto Recommended Mechanistic Empirical Rigid Pavement Design Guide.
Creator: Kampmann, Raphael, Ping, Wei-Chou V., Rambo-Roddenberry, Michelle, Abichou, Tarek, Department of Civil and Environmental Engineering, Florida State University
Abstract/Description: The coefficient of thermal expansion (CTE) is a fundamental property of Portland cement concrete (PCC). The magnitude of temperature-related pavement deformations is directly proportional to the CTE during the pavement design life. Because of its critical effect on PCC performance, it is proposed to be considered for distress and smoothness prediction by the newly developed Mechanistic-Empirical Pavement Design Guide (M-E PDG). To account for M-E PDG implementation in Florida, three typical...
Show moreThe coefficient of thermal expansion (CTE) is a fundamental property of Portland cement concrete (PCC). The magnitude of temperature-related pavement deformations is directly proportional to the CTE during the pavement design life. Because of its critical effect on PCC performance, it is proposed to be considered for distress and smoothness prediction by the newly developed Mechanistic-Empirical Pavement Design Guide (M-E PDG). To account for M-E PDG implementation in Florida, three typical Florida concrete mixtures were experimentally measured for compressive strength, flexural strength, splitting tensile strength, Young's modulus, Poisson's ratio, and CTE according to AASHTO TP-60. The test results revealed that PCC's CTE rapidly increases within the first week but stabilizes after 28 days. However, to accurately analyze the mix designs using the new mechanistic-empirical concept considering all three hierarchy levels, nine different JPCP models were generated. Their PCC layer thicknesses were iteratively determined before the resultant pavement structures were evaluated based on the predicted distresses (faulting and cracking) and smoothness (IRI). It was found, that cracking is the most critical pavement performance criterion for Florida JPCP. Moreover, top-down fatigue damage was isolated to be the controlling failure mechanism because of insignificant faulting and minor smoothness reduction. Based on the thickness idealized JPCP models, a CTE sensitivity matrix was developed for adequate comparison of predicted pavement performance under interchanging CTE values. Despite wide ranging properties, clear patterns were exposed and distinctive performance envelopes arose for certain criteria. It was established that the new M-E PDG, is minimally CTE sensitive to faulting, CTE sensitive to bottom-up damage (for thin PCC layers), and extremely CTE sensitive to top-down damage, cracking, and smoothness.
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Date Issued: 2008
Identifier: FSU_migr_etd-3358
Format: Thesis

Title: Hydrogen Sulfide Attenuation within Landfill Covers.
Creator: Green, Stefan Larae, Abichou, Tarek, Clark, Clayton J., Chen, Gang, Florida State University, FAMU-FSU College of Engineering, Department of Civil and Environmental Engineering
Abstract/Description: There has been much research done on the reduction, or attenuation, of hydrogen sulfide (H2S), particularly within landfill cover soils, as H2S can cause many issues when exposed to the atmosphere. The objective of this research study was to understand hydrogen sulfide (H2S) attenuation within landfill cover soils, and to use mass balancing to determine how much sulfur was retained within each layer of test pad. Both of these were completed through 403 days of monitoring three 65 feet by 35...
Show moreThere has been much research done on the reduction, or attenuation, of hydrogen sulfide (H2S), particularly within landfill cover soils, as H2S can cause many issues when exposed to the atmosphere. The objective of this research study was to understand hydrogen sulfide (H2S) attenuation within landfill cover soils, and to use mass balancing to determine how much sulfur was retained within each layer of test pad. Both of these were completed through 403 days of monitoring three 65 feet by 35 feet lysimeter test pads constructed at the Riverbend Landfill. Test Pad 1 was constructed with 18 inches of local soil and an underlying 6 inch gravel layer. Test Pad 2 was constructed with 12 inches of compost, 6 inches of local soil and an underlying 6 inch gravel layer. Test Pad 3 was constructed with 6 inches of local soil and an underlying 6 inch gravel layer. Monitoring on Test Pad 3 was stopped on April 27th, 2015 due to erosion of the 6 inch soil layer, while Test Pads 1 and 2 were monitored until July 20th, 2015. Readings of landfill gas and H2S inflow, and bottom landfill gas and H2S concentrations were taken in each testing pad on a weekly basis. Bottom H2S loading into the soil layer and top H2S emissions from the soil layer were also measured to determine the removal efficiency of H2S. The average H2S removal efficiency of the test pads is 95%, with Test Pad 1 having a removal efficiency of 99%, Test Pad 2 having a removal efficiency of 99%, and Test Pad 3 having a removal efficiency of 82%. Six soil samples and five water samples were taken to measure sulfur concentration within the testing pads. Soil samples were also taken within each of the layers of each testing location within each test pad to determine the soil type and the water content of each soil layer. Mass balance was calculated by taking the amount of sulfur loaded into the bottom of each testing pad, and subtracting the sum of sulfur loaded into the soil cover, sulfur emitted from the soil cover into the atmosphere, and sulfur removed from the system with water as sulfate. Test Pads 1 and 2 yielded similar results, both retaining about 6000 grams of sulfur within their cover layers, while the results from Test Pad 3 suggest that more sulfur was removed from the system than was originally pushed into the system, which is not possible and suggests errors with either testing methods or the testing pad itself. While the concentrations of sulfur within each test pad layer were measured, there were concerns with their dependability that caused them to not be used to determine the amount of sulfur in each layer.
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Date Issued: 2015
Identifier: FSU_2015fall_Green_fsu_0071N_12959
Format: Thesis

Title: The Development of the Gas Push-Pull Test for Landfill Cover Soil Applications.
Creator: Higgs, Bently Hillory, Abichou, Tarek, Chanton, Jeffrey P., Chen, Gang, Florida State University, FAMU-FSU College of Engineering, Department of Civil and Environmental Engineering
Abstract/Description: The purpose of this thesis was to develop the Gas Push-Pull Test (GPPT) for landfill cover soil applications to measure H2S oxidation. This thesis begins with an overview of solid waste management in the USA, and describes the alternatives for discarding and handling of solid waste. Also, discussions about the components that makeup a landfill to help resist the exposure of contaminants from the solid waste to the environment is elaborated upon. In addition, the ways in which landfill gas is...
Show moreThe purpose of this thesis was to develop the Gas Push-Pull Test (GPPT) for landfill cover soil applications to measure H2S oxidation. This thesis begins with an overview of solid waste management in the USA, and describes the alternatives for discarding and handling of solid waste. Also, discussions about the components that makeup a landfill to help resist the exposure of contaminants from the solid waste to the environment is elaborated upon. In addition, the ways in which landfill gas is generated by placing solid waste into landfills along with mitigation techniques to help attenuate H2S is discussed. Then the most suitable test to quantify in-situ rates of chemical or microbial reactions in the vadose zone or unsaturated zone which is the GPPT, is introduced. As a part of the development of the Gas Push-Pull Test (GPPT), chapter three presents a new methodology that allows for sound implementation of the GPPT in diverse subsurface environments such as a landfill to better understand the transport of gaseous components during the GPPT. For this to be accomplished, many GPPTs were run in fine sand and clayey fine sand with non-reactive gases methane (CH4) and sulfur hexaflouride (SF6) with molecular weights of 16.04 g/mol and 146.06 g/mol. With the data from the GPPTs, an equation or function called the correction factor was formulated to correct for the difference in molecular weights. The correction factor was applied to the GPPTs data and was successful in correcting CH4 and SF6 the non-reactive gases to have a molecular weight equal to the reactive gas Hydrogen Sulfide (H2S) with a molecular weight of 34 g/mol. Now one does not have to search for a tracer with equal transport capabilities like the reactive gas, one need only apply the correction factor. Now you are able to account for how much reactive gas was lost because of transport through the cover soils and by reactions within the cover soils. Once the correction factor was applied, the reacted portion can be used to calculate oxidation or reaction rates of landfill cover soils which is shown in chapter four. Also, to optimize H2S reduction in various soil types, it was important to be able to accurately quantify the reaction rate coefficient, k. Therefore, chapter four focuses on the use of lab and field techniques to examine reaction rates of H2S with fine sand, silty fine sand, clayey fine sand, compost and landfill cover soil. First, a series of laboratory flask experiments were conducted to assess the reaction rates of various soil types with no moisture, and then with varying water content from 10% to 60%. Next, the Gas Push-Pull Test (GPPT) was conducted in the field in different soil types to assess reaction rates. The laboratory results showed that the landfill cover soil had the highest reaction rate of 41.87 hr-1 when the soil had no moisture. Whereas compost had the highest reaction rate from 5.84 hr-1 to 9.98 hr-1 when moisture content increased from 10% to 60%, respectively. The laboratory results showed that lab-measured reaction rates of dry soils are strongly related to total iron content. For instance, the landfill cover soil had the highest reaction rate of 41.87 hr-1 with an iron content of 31,000 mg/kg of soil. On the other hand, fine sand had the lowest reaction rate of 1.47 hr-1 with an iron content of 100 mg/kg. The reaction rate with water was also measured to be 1.44 hr-1. It was noticed that water causes the reaction k to decrease for soils that had high k values with 0% water content. Whereby water causes the reaction k of compost to increase. The GPPT well-mixed and plug-flow reactor models' reaction rates for fine sand ranged from 1.63 hr-1 to 3.02 hr-1 and from 0.45 to 2.02, respectively. The GPPT well-mixed and plug-flow reactor models reaction rates for clayey fine sand ranged from 63.80 hr-1 to 144.49 hr-1 and from 47.77 hr-1 to 74.08 hr-1, respectively. Lastly, the GPPT well-mixed and plug-flow reactor models reaction rate values for landfill cover soil ranged from 55.83 hr-1 to 318.18 hr-1 and from 32.69 hr-1 to 110.14 hr-1, respectively. Also, fine sand tested for reaction rates in the flask and with the GPPT was not significantly different because of the homogeneity of the soil. However, the clayey fine sand and landfill cover soil tested for reaction rates was significantly different because of the heterogeneity of the soils. Both the flask test and the GPPT are easy and convenient to perform, but the GPPT is the most reliable because it quantifies in-situ reaction rates. Furthermore, to understand the attenuation of H2S, chapter five looks at lab and field scale studies that were conducted with potential landfill cover soils. For the laboratory experiment a rigid translucent plastic cylinder with a diameter of 5 1/2 inches and a height of 24 inches was constructed. The inside of the column from bottom to top was composed of a 2mm geotextile underlayment, a five-inch layer of course gravel, another two pieces of 2mm geotextile underlayment, twelve inches of 50-50 compost peat (by volume) mixture, and a six-inch air space. Then landfill gas (LFG) was injected into the column to assess the mitigation of H2S. After pumping 28,000 L of LFG was introduced into the column, which indicated the average instantaneous removal efficiency during the monitoring period was 85.7%. Also, the total mass of H2S introduced into the column was approximately 3.12g, the total mass emitted was 0.28g, and the total mass retained by the 1 foot soil mix was 2.84g. Therefore cumulative removal efficiency was 91%. In addition, to check for physical and chemical adsorption in the column, the saturated four-inch bottom layer of the soil mix was removed and tested for total sulfur. The sulfur adsorption capacity of the soil mixture was 2.2 g of total S per kg of dry mass of soil mix. The Michaelis-Menten kinetics parameters to understand the biological oxidation of H2S was determined to be Vmax of 450 nmol/s/kg of dry soil mix and a half saturation constant Km of 30 ppm. Also, a field scale study was conducted by constructing three 65x35 lysimeter test pads at the Riverbend Landfill. The test pads were made up of a composition of local soil and compost. As of October 2014, the average removal efficiency of the test pads is 99%. Test pad II with 6 inches of local soil on the bottom and 12 inches of local soil on the top had the highest H2S removal efficiency of 100%. Whereby test pad I with 18 inches of local soil and test pad III with 6 inches of local soil, both had 99% H2S removal efficiency. Also, continual monitoring of the test pads will persist, because of the increase of LFG flow into the test pads by increasing the orifice plates to 1 inch. In addition, the total sulfur and iron content of the test pads will be examined especially since LFG is still being introduced to the test pads. Lastly the newly developed GPPT will be utilized to study the field scale H2S oxidation of each test pad.
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Date Issued: 2014
Identifier: FSU_migr_etd-9187
Format: Thesis

Title: Numerical Simulation of Dynamic Wave Force on Coastal Structures under Extrem Storm Surge Conditions.
Creator: Xiao, Hong, Huang, Wenrui, Hu, Bill, Hilton, Amy Chan, Abichou, Tarek, Department of Civil and Environmental Engineering, Florida State University
Abstract/Description: Sea waves associated with storm surge is a key factor in the safety of coastal structures. Most of the damages on coastal structures during a storm event are caused by waves. Forces created by waves breaking against a vertical surface are often 10 or more times higher than the force created by high speed winds during a storm event. In hurricane season, a combination of storm surge and waves may cause overtopping of coastal protection structures such as breakwaters, dikes, seawalls, resulting...
Show moreSea waves associated with storm surge is a key factor in the safety of coastal structures. Most of the damages on coastal structures during a storm event are caused by waves. Forces created by waves breaking against a vertical surface are often 10 or more times higher than the force created by high speed winds during a storm event. In hurricane season, a combination of storm surge and waves may cause overtopping of coastal protection structures such as breakwaters, dikes, seawalls, resulting in flooding and damaging of the areas behind these structures. When a wave crest is overtopping a coastal structure, complex vortices patterns are generated behind the structure. The vortices induced by wave result in the swash of the seabed, the stagnation of contamination, the settlement of mud and sand around the coastal structures, and the resonance of the structures. As matter of fact, wave force on structures is a very important issue in design, construction and management of offshore and coastal structures. In this dissertation, a wave model based on Reynolds-Averaged-Navier-Stokes (RANS) equations is developed for estimating dynamic wave forces on coastal structures. Turbulent models are used for the closure of RANS equations. A generating-absorbing numerical wave paddle is used to generate waves, and an absorbing sponge layer for absorbing wave is adopted in front of the open boundary to absorb wave energy. In order to track the movement of the free surface, the Youngs' version of Volume of Fluid (VOF) method is used to reconstruct the profile of the free surface at every time step. The wave force model is validated against available experimental data and analytical results of wave force on coast structures. After validation, the model is applied to address several engineering problems in coastal engineering field: 1) Numerical modeling of wave run-up and forces on an idealized beachfront house The wave model is applied to estimate the impact of a solitary wave on an idealized beachfront house located at different elevations on a plane beach. The model is satisfactorily tested against the experimental data of wave run-up, and the analytical solution of wave forces on vertical walls. The time histories of wave profiles, forces, and overturning moments on the idealized house are demonstrated and analyzed. The variations of wave forces and overturning moments with the elevation of the idealized beachfront house are also investigated. 2) Numerical modeling of dynamic wave force acting on Escambia bay bridge deck during Hurricane Ivan Bridge decks in Escambia Bay were damaged during the storm surge of Hurricane Ivan in 2004. The wave model is used to investigate dynamic wave forces exerted on the bridge deck. The model was satisfactorily tested against experimental data of uplift wave forces on horizontal plates. The validated model was applied to investigate wave forces acting on the bridge deck in Escambia Bay in the case of Hurricane Ivan. The time history of wave profiles, turbulent velocity fields, and dynamic uplift and horizontal forces acting on the full-scale bridge deck were simulated and analyzed. Results indicate that, during the storm surge event of Hurricane Ivan, the maximum uplifting wave forces were larger than the weight of the simply supported bridge deck, causing direct damage to the bridge deck. Wave forces on three different deck elevations are discussed. 3) Effects of submersion depth on wave uplift force acting on bridge decks during Hurricane Katrina A large portion of the Biloxi Bay Bridge was submerged and destroyed by surface waves and storm surge associated with Hurricane Katrina in 2005. The time history of wave forces exerted on the Biloxi Bay Bridge during Hurricane Katrina was investigated by the wave model. In order to evaluate the maximum uplift wave force, five different bridge deck elevations submerged at different water depths were investigated. The wave profiles, velocity field in the vicinity of the bridge, and dynamic wave forces on the decks were analyzed. Results indicate that the uplift force on the submerged bridge deck span exceeded its own weight under the extreme wave and storm surge conditions during Hurricane Katrina. Moreover, the numerical simulations suggest that the maximum uplift wave force occurred when the storm surge water level reached the top of the bridge deck. 4) Numerical modeling of levee overtopping during Hurricane Katrina The wave model applied to estimate the impact of overtopping on levee during storm surge. The model was satisfactorily tested against empirical equation of overflow discharge at a vertical seawall, and experimental data of overtopping discharge at a sloping seawall. The validated model was used to simulate wave overtopping of the levee system during storm surge of Hurricane Katrina. The time history of wave profiles and velocity magnitude field in the vicinity of the levee are demonstrated and analyzed. It is concluded that the failure of parts of the levee system was caused by erosion during wave overtopping. 5) Numerical modeling of interactions of solitary wave and current in the vicinity of a horizontal cylinder The numerical model is applied to study the interaction of solitary wave and uniform current and their impacts on a horizontal cylinder near the free surface. The model is satisfactorily tested against both the experimental data of forces on a circular cylinder, and the analytical solution of solitary waves. The validated model was applied to simulate solitary wave, uniform current, and their interaction with coastal structures. The hydrodynamic features of velocity field and vortex contours are demonstrated and analyzed.
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Date Issued: 2009
Identifier: FSU_migr_etd-0412
Format: Thesis

Title: Feasibility Study, Primary Designs and Development of Alternative Evapotranspiration Covers for Landfills and Waste Dump Sites in Tropical Locations.
Creator: Escobar, Francisco Jose, Abichou, Tarek, Cheng, Gang, Clark, Clayton, Department of Civil and Environmental Engineering, Florida State University
Abstract/Description: People generate a large and ever-increasing volume of waste, which originates in rural and urban areas, industrial operations and other activities. In spite of waste recycling, which is the solution to the huge amount of solid waste, a large part of it is deposited into landfills, dumps, etc.Landfills are, at present, the most widely used waste disposal facilities. Final cover systems are used at landfills and other types of waste disposal sites to control moisture and percolation, promote...
Show morePeople generate a large and ever-increasing volume of waste, which originates in rural and urban areas, industrial operations and other activities. In spite of waste recycling, which is the solution to the huge amount of solid waste, a large part of it is deposited into landfills, dumps, etc.Landfills are, at present, the most widely used waste disposal facilities. Final cover systems are used at landfills and other types of waste disposal sites to control moisture and percolation, promote surface water runoff, and minimize erosion. In addition, covers prevent direct exposure to the waste, control gas emissions and odors, prevent occurrence of disease vectors and other nuisances, and meet aesthetic and other end-use purposes. The Resource Conservation and Recovery Act (RCRA) Subtitle D, requires the use of landfill covers to meet these needs.Prescribed covers, permitted by current regulations, are based on a barrier concept that requires them to employ resistive principles, i.e., a layer having low saturated hydraulic conductivity. The most important focus of this study, is the EvapoTranspiration cover (ET) concept, which utilizes one or more vegetated soil layers to retain water until it is either transpired through vegetation, or evaporated from the soil surface. These cover systems rely on the water storage capacity of the soil layer, rather than low hydraulic conductivity materials, to minimize percolation. ET cover designs are based on using the hydrological processes and water balance components at a specific site, which includes the water storage capacity of the soil, precipitation, surface runoff, evapotranspiration and infiltration. The objective of this study is to determine the feasibility of developing and using ET Covers in tropical locations with medium to high precipitation. Puerto Rico can be assimilated as a part and sample of the typical average "Tropical Zones," so the study was concentrated there. The obtained conclusions can be applied later, along with the same principles, to Tropical Zones in general, which will have similar characteristics of rainfall, vegetation, soil texture and classification, and temperature. The study consisted of collecting climate, soil, and vegetation data and characteristics from six regions or "Ecozones" determined on the Island of Puerto Rico, as a representative of the "Tropical Sub-climate." The collected data was then used as input of a software called PR-ET to calculate the PET or ETo of the location and then the basis data of a flow model (HYDRUS 1-D) to simulate infiltration into the waste during peak weather events. PET and ETo are similar terms and are defined as the "Potential Evapotranspiration." Simulations were performed to evaluate the effect of the weather period, the effect of soil thickness, the effect of vegetation, the LAI (Leaf Area Index) and finally to determine what regions in Puerto Rico show potential for implementing ET covers.Results from this study showed some sub-regions (or locations) belonging to the six Ecozones (or regions) of Puerto Rico were able to meet the preliminary requirements for hydrological performance as required by the RCRA. However, field evaluation of these designs should be performed before full implementation of ET covers in these regions. Of the 21 locations studied in the preliminary design, 15 were adequate for study by modeling them to confirm the feasibility of using the Evapotranspiration covers in them. After this modeling or simulation was conducted, the results were as follows: eight locations can effectively use ET covers using as covering vegetation pastures. Five locations can use ET covers, but the vegetation needs to be changed using then shrubs and grass. The other locations are being rejected for this study. The selected locations are supposed to have thickness less than 2.0 m.
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Date Issued: 2011
Identifier: FSU_migr_etd-0523
Format: Thesis

Title: Development of the Gas Push Pull Test for Hydrogen Sulfide Oxidation.
Creator: Lawson, Jacob Brinton, Abichou, Tarek, Chanton, Jeffery, Clark, Clayton, Department of Civil and Environmental Engineering, Florida State University
Abstract/Description: ABSTRACT A limited number of studies using various types of cover materials to attenuate H2S emissions have been performed both at the laboratory and field scales. These results have demonstrated that H2S emissions can be effectively reduced using compost, fine concrete, and lime-amended sandy soils as cover materials using several mechanisms (Plaza et al. 2007, Xu, 2005, Sungthong 2010). These mechanisms are: (1) Hydrogen sulfide is consumed by bacteria found in soil that oxidizes hydrogen...
Show moreABSTRACT A limited number of studies using various types of cover materials to attenuate H2S emissions have been performed both at the laboratory and field scales. These results have demonstrated that H2S emissions can be effectively reduced using compost, fine concrete, and lime-amended sandy soils as cover materials using several mechanisms (Plaza et al. 2007, Xu, 2005, Sungthong 2010). These mechanisms are: (1) Hydrogen sulfide is consumed by bacteria found in soil that oxidizes hydrogen sulfide to elemental sulfur or sulfate, (2) Clay or organic matter in soils may also sorb hydrogen sulfide (soil microorganisms are not involved in the sorption process), and (3) H2S may be oxidized by reaction with soil minerals, particularly ferric iron. Such mechanisms are well understood from the significant amount of research performed on H2S gas removal using biofiltration. Additionally, under aerobic landfill cover conditions, considerable research has been performed using microbiological methane oxidation to mitigate methane emissions from municipal solid waste. One of the main issues regarding the implementation of approaches for the reduction of H2S emissions from landfills is the lack of a proper technique to assess the level of H2S oxidation and reaction under field conditions. Developing such a technique would allow the determination of H2S oxidation capacity of different cover materials and different cover designs under different climatic conditions. One possible technique that could be employed is the Gas Push Pull Test (GPPT). The general aim of this thesis is to develop the GPPT method for a reactive gas like H2S, which has not been done before. GPPT is a single well gas-tracer test in which inert gases are used as non-reactive tracers for the reactive gas (methane) or in this case, H2S. During the test, a mixture of tracer and reactive gases is injected (pushed) into the soil. During a transition phase, the soil "air" mixes with the injected gases where it is available to microorganisms or minerals. The mixture of soil "air" and injected gas is then extracted (pulled) from the same location. The quantification of oxidation is then based on the analysis of the breakthrough curves (relative concentrations) of the reactive and the tracer gases. It is expected that the tracer concentrations at the injection/extraction points decrease as a result of physical transport processes, whereas the attenuation of the reactive gas is a result of physical transport processes, chemical oxidation, and microbial (and others) activities. A lab study was completed to assess the reactivity of H2S by different soil types typically used in landfill cover construction. The reactivity of H2S was characterized by zeroth-order kinetics as well as correlating the reactivity to water and iron content of the soil materials. The lab study only investigated physical and chemical processes that attenuate H2S. In addition to the laboratory study, a field study was completed to develop proper methods in performing a (GPPT) to measure the capacity of soil materials to oxidize H2S. The objectives were to experimentally compare transport of the reactant gas H2S and tracer gases during GPPTs as a function of varying injection/extraction flow rates in a porous medium and in the absence of microbial activity. Additionally, the relative importance of molecular diffusion, advection, and transfer into the water phase of H2S during GPPTs was also evaluated as well as developing a correction ratio that would allow the use of tracers with dissimilar molecular weights.
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Date Issued: 2013
Identifier: FSU_migr_etd-7878
Format: Thesis

Title: College of Engineering Characterization of Microbial Activity in Soils Nearby Landfills in Northwest Florida.
Creator: Williams, Mitchell Duren, Chen, Gang, Hilton, Amy Chan, Abichou, Tarek, Department of Civil and Environmental Engineering, Florida State University
Abstract/Description: Elevated iron concentrations have been observed in the groundwater downgradient of the landfills in Northwest Florida. It is suspected microbial mediated iron reduction should be responsible for the iron release. The purpose of this research is to characterize the microbial community in the soils nearby landfills in Northwest Florida to determine the dominant bacterial species. The iron rich soil in Northwest Florida and leachate from landfills are considered the primary contributors to the...
Show moreElevated iron concentrations have been observed in the groundwater downgradient of the landfills in Northwest Florida. It is suspected microbial mediated iron reduction should be responsible for the iron release. The purpose of this research is to characterize the microbial community in the soils nearby landfills in Northwest Florida to determine the dominant bacterial species. The iron rich soil in Northwest Florida and leachate from landfills are considered the primary contributors to the elevated iron concentrations observed in groundwater. Iron reducing bacteria are capable of releasing soluble Fe (II) by reducing Fe (III) bound to the soil minerals. The leachate has potential for providing carbon sources for the reaction, allowing the bacteria to more rapidly reduce the iron in the soil. In this research, the soils from sixteen landfills (fifteen Northwest Florida counties) were characterized through sieve analysis and the bacteria were quantified and identified. Traditional plate count method was used for bacterial quantification and morphology by means of microscopy and Polymerase Chain Reaction (PCR) were utilized for bacterial identification. The plate counts resulted in 0.03 million to 2.0 million colony-forming units (CFU) per gram of soil. The identification through morphology found typical rod and cocci bacteria to be the dominating species. Although potentially iron reducing bacteria were identified through morphology, they were not confirmed through DNA analysis. They need further enriched culturing in order to observe obvious iron reducing. The PCR analysis identified typical soil bacteria, Bacillus subtilis, Bacillus cereus, Bacillus thuringiensis, and Pseudomonas aeruginosa. These bacteria are common soil bacteria that are well characterized. The sieve analysis of the soils showed a correlation of increased bacterial population in well-graded soils. The soils also showed an increase in water content when there was a higher percentage of finer particles. However, increased water content and finer particles resulted in lower bacterial populations. Further studies are currently underway to quantify the iron release from the soils and the effects the leachate have on the bacterial processes.
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Date Issued: 2007
Identifier: FSU_migr_etd-0975
Format: Thesis

Title: An Environmental Systems Analysis of Cathode Ray Tube Waste Management.
Creator: Lundy, Chancee, Chan-Hilton, Amy B., Abichou, Tarek, Nnaji, Soronnadi, Department of Civil and Environmental Engineering, Florida State University
Abstract/Description: As new technology becomes available, consumers are likely to dispose of old equipment in favor the most upgraded electronics. It becomes increasingly difficult to manage electronic solid and hazardous waste when the lifespan of such devices is decreasing. In the computer industry, new technology demands that we upgrade software and eventually hardware on a consistent basis to avoid malfunction. Of particular concern are computer monitors, which contain 4-8 pounds of lead in the cathode ray...
Show moreAs new technology becomes available, consumers are likely to dispose of old equipment in favor the most upgraded electronics. It becomes increasingly difficult to manage electronic solid and hazardous waste when the lifespan of such devices is decreasing. In the computer industry, new technology demands that we upgrade software and eventually hardware on a consistent basis to avoid malfunction. Of particular concern are computer monitors, which contain 4-8 pounds of lead in the cathode ray tube. According to a study completed by Townsend et al, cathode ray tubes from televisions and computer monitors exceed the 5 mg/L leaching limit as set forth in the Environmental Protection Agency's Toxicity Characteristic Leaching Procedure. The cathode ray tubes from these devices leached over 18 mg/L of lead. (1999) In the state of Florida most counties recycle computer monitors such that these toxic machines will not end up in the landfill where there is a potential for groundwater leaching. The cost for processing computer monitors is a burden to the landfill; therefore, this research minimized cost to the landfill through a linear programming approach using Microsoft Excel Solver. Using this program, an advanced disposal fee was imposed to residents within the state of Florida to alleviate the cost burden from the local governments. After using various scenarios to impose these fees, it was determined that the advanced disposal fee could be a partial solution to the funding issues for the counties. It does indeed assist counties in keeping these hazardous computer monitors out of the landfill and lower costs for processing these items with various recycling facilities.
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Date Issued: 2006
Identifier: FSU_migr_etd-0999
Format: Thesis

Title: Methane Emission and Oxidation Through Landfill Covers.
Creator: Yuan, Lei, Abichou, Tarek, Chanton, Jeffrey, Tawfiq, Kamal, Ping, Wei-Chou V., Department of Civil and Environmental Engineering, Florida State University
Abstract/Description: This dissertation presents the work of investigating methane emission and oxidation through landfill covers. Methane as a major source of greenhouse and is being emitted from solid waste landfill at a tremendous rates. These emissions could be mitigated by methanotrophic bacteria in enriched and non-enriched soil covers. Compost biofilters were constructed to study the methane oxidation capacity of compost. The aged chipped yard waste compost was obtained from Leon County landfill (Florida,...
Show moreThis dissertation presents the work of investigating methane emission and oxidation through landfill covers. Methane as a major source of greenhouse and is being emitted from solid waste landfill at a tremendous rates. These emissions could be mitigated by methanotrophic bacteria in enriched and non-enriched soil covers. Compost biofilters were constructed to study the methane oxidation capacity of compost. The aged chipped yard waste compost was obtained from Leon County landfill (Florida, USA). A one-dimensional dynamical numerical model was developed to simulate the methane transport and oxidation through the biofilter. This model was designed to incorporate dynamic parameters and use flux bottom boundary, which is measured by a flow meter. General agreements of methane outflux and oxidations were obtained between model simulation and experimental data. Field scale control cells and biocells were evaluated in the same landfill for methane emission and oxidation. Methane oxidation in biocells was significantly higher than in control cells. When outliers were removed, methane emission from biocells was significant less than from control cells. A numerical model was developed to separate blockage of the thicker biocells cover and the biological oxidation. Results showed that the low emission from biocells is caused by blockage of soil cover underneath the compost cover as well the high oxidation capacity of this compost cover. An additional modeling investigation was conducted to evaluate how landfill final earthen cover's construction and climate conditions affect methane emission and oxidation under different boundary condition and different soil oxidation capacities. This numerical model combined a water and heat flow model (HYDRUS1D) and a gas transport and oxidation model. Simulations showed that soil covers in subhumid areas can prevent high methane emission with blockage and decent oxidation capacity. In semi-arid sites, higher emission was obtained due to the higher air filled void space of the soil. Oxidation capacities in semi-arid sites are higher than those in subhumid sites since influxes of methane are higher in semiarid sites. High pressure underneath the cover caused higher emission in all sites. Even with active gas collection system (vacuum pressure), emissions were significant in semiarid climates.
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Date Issued: 2006
Identifier: FSU_migr_etd-0919
Format: Thesis

Title: Reducing Hydrogen Sulfide (H2S) Concentrations at Wastewater Collection Systems and Treatment Facilities Using Chemical Oxidation.
Creator: Thomas, Dornelle S., Hilton, Amy Chan, Chen, Gang, Abichou, Tarek, Department of Civil and Environmental Engineering, Florida State University
Abstract/Description: Wastewater collection systems and treatment facilities are known for emitting offensive odors that cause neighboring residents to complain. One of the main odor compound contributors is hydrogen sulfide (H2S). Presently, H2S removal from wastewater facilities is mainly being accomplished by biological means relying heavily on the use of microorganisms. However, the use of microorganisms requires a more consistent and stable environment. In the absence of the previously stated conditions, the...
Show moreWastewater collection systems and treatment facilities are known for emitting offensive odors that cause neighboring residents to complain. One of the main odor compound contributors is hydrogen sulfide (H2S). Presently, H2S removal from wastewater facilities is mainly being accomplished by biological means relying heavily on the use of microorganisms. However, the use of microorganisms requires a more consistent and stable environment. In the absence of the previously stated conditions, the removal of H2S has to be carried out by other means. Therefore, an alternative for wastewaters with unstable characteristics requiring minimal maintenance/human involvement is preferred to deal with H2S emissions. This study investigated the effectiveness of chemical oxidation by employing three oxidants, 50% hydrogen peroxide (H2O2), 12% sodium hypochlorite (NaOCl), and 5% potassium permanganate (KMnO4) at mitigating H2S aqueous and gas concentrations at wastewater collection systems and treatment facilities. The chemicals were supplied to the systems throughout four distinct testing phases using peristaltic pumps. H2S(g) levels were obtained using a Jerome Meter (860 model) while the dissolved sulfide concentrations were measured using a LaMotte Sulfide Test Kit. This study found that of the three chemicals chosen, H2O2 is most effective and efficient at removing H2S from wastewater collection and treatment facilities. However, throughout this study, H2S(g) removal efficiencies were affected by the physical conditions at the testing facilities. Therefore, after taking the corrective action needed to improve facility conditions, further investigation is required to appropriately evaluate the use of H2O2 at odor mitigation.
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Date Issued: 2007
Identifier: FSU_migr_etd-1580
Format: Thesis

Title: Evaluation of Granular Subgrade Modulus from Field and Laboratory Tests.
Creator: Sheng, Biqing, Ping, Wei-Chou Virgil, Abichou, Tarek, Moses, Ren, Department of Civil and Environmental Engineering, Florida State University
Abstract/Description: The Resilient Modulus of pavement subgrade materials is an essential parameter for determining the stress-stain characteristics of pavement structures subjected to traffic loadings for a mechanistically based flexible pavement design procedure. The modulus of subgrade reaction is a required parameter for design of rigid pavements. The load-deformation characteristics of the granular subgrade soils were investigated using the laboratory triaxial test, test-pit plate load test, and field rigid...
Show moreThe Resilient Modulus of pavement subgrade materials is an essential parameter for determining the stress-stain characteristics of pavement structures subjected to traffic loadings for a mechanistically based flexible pavement design procedure. The modulus of subgrade reaction is a required parameter for design of rigid pavements. The load-deformation characteristics of the granular subgrade soils were investigated using the laboratory triaxial test, test-pit plate load test, and field rigid plate load bearing test. Several typical subgrade soils used for pavement construction in Florida were obtained for evaluation. The resilient modulus of subgrade materials were evaluated by a laboratory triaxial testing program. The resilient properties of subgrade materials were found to be strongly influenced by moisture content and test procedure. A full-scale laboratory evaluation of the subgrade performance was then conducted in a test-pit facility to simulate the actual field conditions. The subgrade materials were tested under various moisture conditions that simulated different field groundwater levels. It was shown that the resilient modulus of subgrade materials increases with the decrease in groundwater level. In addition, the field plate load testing program was carried out to evaluate the bearing characteristics of pavement base, subgrade, and embankment soils. A hyperbolic model was used to represent the relationship of the load-deformation curve obtained from the field plate load bearing test. Correlation relationships were established between the laboratory resilient modulus and the resilient modulus measured using the test-pit facility. It was shown that the resilient modulus measured from the laboratory test could be used to predict the resilient deformation of the pavement subgrade layers if an appropriate calculation method was used. The correlation relationship between the subgrade soil resilient modulus and the modulus of subgrade reaction was also established; it was found to be close to the theoretical relationship from the AASHTO design guide. These correlation relationships could be utilized in the Florida pavement design guide in order to better predict the resilient deformation of pavement subgrades.
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Date Issued: 2010
Identifier: FSU_migr_etd-1773
Format: Thesis

Title: The Use of O₃ Advanced Oxidation Processes for Landfill Leachate Pretreatment.
Creator: Ghazi, Niloufar Mirsaeid, Chen, Gang, Clark, Clayton, Abichou, Tarek, Department of Civil and Environmental Engineering, Florida State University
Abstract/Description: The final discharge point for collected landfill leachates is frequently the local municipal wastewater treatment facility. The salinity, color, and/or nutrient and organics contamination of leachates often necessitate some form of pre-treatment. When advanced oxidation processes (AOPs) are considered for pre-treatment, the unique composition of dissolved organic matter (DOM) and the relatively high concentrations of some inorganic solutes in leachate will inhibit treatment efficiency. The...
Show moreThe final discharge point for collected landfill leachates is frequently the local municipal wastewater treatment facility. The salinity, color, and/or nutrient and organics contamination of leachates often necessitate some form of pre-treatment. When advanced oxidation processes (AOPs) are considered for pre-treatment, the unique composition of dissolved organic matter (DOM) and the relatively high concentrations of some inorganic solutes in leachate will inhibit treatment efficiency. The most important benchmark for design of AOPs is the expected steady-state production of free radical (*OH). Without a quantitative assessment of total *OH consumption in high-strength waste water, like a landfill leachate, efficient AOP treatment is uncertain. For this reason, two landfill leachates, distinct in color, DOM, population served by municipal solid waste facility, and age of landfill, were characterized for *OH-scavenging using a well-established competition kinetics method. After stripping the samples of inorganic carbon, the DOM in leachate from mature (stabilized) landfill was found to react with *OH at a rate of 9.76 x 108 M-1s-1. However, DOM in leachate from newer landfill was observed to scavenge available *OH at a faster rate (8.28 x 109 M-1s-1). The combination of fast rate of reaction with *OH and abundance of DOM in the sampled leachate severely limited the contribution of *OH to degradation of an O3- and *OH-labile organic probe compound (bisphenol-a) in the ozonated mature leachate (f*OH= 0.03). Substantial dosing of both O3 and H2O2 (> 70 mg/L and >24 mg/L, respectively) may be required to see at least 1-log-removal (>90%) of an *OH-selective leachate contaminant (parachlorobenzoic acid) in a mature landfill leachate.
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Date Issued: 2013
Identifier: FSU_migr_etd-8606
Format: Thesis

Title: Evaluation of Engineering Properties of Hot Mix Asphalt Concrete for the Mechanistic-Empirical Pavement Design.
Creator: Xiao, Yuan, Ping, Wei-Chou V., Niu, Xufeng, Abichou, Tarek, Sobanjo, John, Department of Civil and Environmental Engineering, Florida State University
Abstract/Description: Hot Mix Asphalt (HMA) is a viscoelastic material and has been broadly used in pavement structures. It is important to understand the mechanism of complex behaviors of HMA mixtures in field for improving pavement mechanical performance. Aggregate gradation and asphalt binder are two key factors that influence the engineering properties of HMA. The asphalt binder plays a significant role in elastic properties of HMA and it is the essential component that determines HMA's viscous behavior. Many...
Show moreHot Mix Asphalt (HMA) is a viscoelastic material and has been broadly used in pavement structures. It is important to understand the mechanism of complex behaviors of HMA mixtures in field for improving pavement mechanical performance. Aggregate gradation and asphalt binder are two key factors that influence the engineering properties of HMA. The asphalt binder plays a significant role in elastic properties of HMA and it is the essential component that determines HMA's viscous behavior. Many research works suggest that Styrene-Butadiene-Styrene (SBS) polymer is a promising modifier to improve the asphalt binder, and hence to benefit the HMA viscoelastic properties. The specific beneficial characteristics and appropriate polymer concentration need to be identified. In addition, aggregate gradation requirements have been defined in Superpave mix design criteria. However, a potentially sound coarse mixture with the gradation curve passing below the coarse size limit may be disqualified from being used. There is a need to evaluate the Superpave gradation requirements by studying mixtures purposely designed exceeding the control limits. Moreover, the mechanical parameters adopted by AASHTO to characterize HMA properties are shifting from indirect diametral tensile (IDT) test to dynamic modulus test (DMT), because the DMT has the ability to simulate real traffic conditions and to record more viscoelastic information of HMA. Thus, the DMT and the IDT test for implementing the AASHTO Mechanistic-Empirical Design Guide (M-E PDG) are needed to be discussed. The primary objective of this research study was to evaluate the fracture mechanics properties of HMA concrete and to study the correlation between the DMT and the IDT test for Superpave mixtures. An experimental program was performed on asphalt mixtures with various types of materials. The laboratory testing program was developed by applying a viscoelastic fracture mechanics-based framework that appeared to be capable of describing the whole mechanical properties of HMA according to past research studies. The goals for these experiments are to evaluate the effect of aggregate type, the effect of gradation adjustment to control mix designs, and the effect of SBS polymer on fracture mechanics properties of HMA mixtures. Two standard coarse mixes were selected as control levels for fracture mechanics tests: one granite mixture and one limestone mixture. Each control mix design was modified to two different gradation levels with the control asphalt binder (PG 67-22) and three SBS polymer content levels (3.0%, 4.5%, and 6.0%) with the original aggregate gradation. The experimental program for dynamic complex modulus test involved 20 Superpave asphalt concrete mixtures commonly used in Florida with a range of aggregates and mix designs. Data evaluation of the test results indicated the increase of nominal maximum size aggregate amount by 5% to 15% to the standard coarse mix designs had negligible effect on HMA fracture mechanics properties. The SBS polymer-modified asphalt binder improved the fracture mechanics behavior of asphalt mixtures comprehensively. The limestone materials hold advantages over granite materials in improving the performance of thermal cracking at low service temperatures and the rutting resistance at high service temperatures. The master curve construction and linear regression analysis indicated that the total resilient modulus increased with an increase in dynamic modulus at a specific loading frequency. The resilient modulus values were comparable with the dynamic modulus values at the loading frequency of 4 Hz. A correlation relationship was developed for predicting the dynamic modulus from existing resilient modulus values of the asphalt concrete mixture in implementing the mechanistic-empirical pavement design.
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Date Issued: 2009
Identifier: FSU_migr_etd-0411
Format: Thesis

Title: Analysis and Predictions of Extreme Coastal Water Levels.
Creator: Xu, Sudong, Huang, Wenrui, Niu, Xufeng, Nnaji, Soronnadi, Abichou, Tarek, Department of Civil and Environmental Engineering, Florida State University
Abstract/Description: Understanding the characteristics of probability distribution of extreme water levels is important for coastal flood mitigation and engineering design. In this study, frequency analysis has been conducted to investigate probability distributions along the coast of the U.S. by using three-parameter General Extreme Value (GEV) method. The GEV model combines three types of probability distributions (Type I for Gumbel distribution, Type II for Fretchet, or Type III for Weibull) into one...
Show moreUnderstanding the characteristics of probability distribution of extreme water levels is important for coastal flood mitigation and engineering design. In this study, frequency analysis has been conducted to investigate probability distributions along the coast of the U.S. by using three-parameter General Extreme Value (GEV) method. The GEV model combines three types of probability distributions (Type I for Gumbel distribution, Type II for Fretchet, or Type III for Weibull) into one expression. Types of distributions can be clarified by one of the three parameters of the GEV model for the corresponding studied stations. In this study, the whole U.S. coast was divided into four study areas: Pacific Coast, Northeast Atlantic Coast, Southeast Atlantic Coast and Gulf of Mexico Coast. Nine National Oceanic and Atmospheric Administration (NOAA) stations with a long history of data (more than 70 years) in the four study areas were chosen in this study. Parameters of the GEV model were estimated by using the annual maximum water level of studied stations based on the Maximum Likelihood Estimation (MLE) method. T-test was applied in this study to tell if the parameter, , was greater than, less than or equal to 0, which was used to tell the type of the GEV model. Results show that different coastal areas have different probability distribution characteristics. The characteristics of probability distribution in Pacific Coast and Northeast Atlantic Coast are similar with extreme value I and III model. The Southeast Atlantic Coast and Gulf of Mexico Coast were found to have similar probability distribution characteristics. The probability distributions were found to be extreme value I and II model, which are different from those of the Pacific Coast and Northeast Atlantic Coast. The performance of the GEV model was also studied in the four coastal areas. GEV model works well in the five studied stations of both the Pacific Coast and the Northeast Atlantic Coast but does not work well in the Southeast Atlantic Coast and the Gulf of Mexico Coast. Adequate predictions of extreme annual maximum coastal water levels (such as 100-year flood elevation) are also very important for flood hazard mitigation in coastal areas of Florida, USA. In this study, a frequency analysis method has been developed to provide more accurate predictions of 1% annual maximum water levels for the Florida coast waters. Using 82 and 94 years of water level data at Pensacola and Fernandina, performances of traditional frequency analysis methods, including advanced method of Generalized Extreme Value distribution method, have been evaluated. Comparison with observations of annual maximum water levels with 83 and 95 return years indicate that traditional methods are unable to provide satisfactory predictions of 1% annual maximum water levels to account for hurricane-induced extreme water levels. Based on the characteristics of annual maximum water level distribution Pensacola and Fernandina stations, a new probability distribution method has been developed in this study. Comparison with observations indicates that the method presented in this study significantly improves the accuracy of predictions of 1% annual maximum water levels. For Fernandina station, predictions of extreme water level match well with the general trend of observations. With a correlation coefficient of 0.98, the error for the maximum observed extreme water level of 3.11 m (NGVD datum) with 95 return years is 0.92 %. For Pensacola station, the prediction error for the maximum observed extreme water level with a return period of 83 years is 5.5 %, with a correlation value of 0.98. In frequency analysis of 100 year coastal flood (FEMA 2005), annual extreme high water levels are often used. However, in many coastal areas, long history data of water levels are unavailable. In addition, some water level records may be missed due to the damage of measurement instruments during hurricanes. In this study, a method has been developed to employ artificial neural network and harmonic analysis for predicting extreme coastal water levels during hurricanes. The combined water levels were de-composed into tidal signals and storm surge. Tidal signal can be derived by harmonic analysis, while storm surge can be predicted by neural network modeling based on the observed wind speeds and atmospheric pressure. The neural network model employs three-layer feed-forward backgropagation structure with advanced scaled conjugate training algorithm. The method presented in this study has been successfully tested in Panama City Beach and Apalachicola located in Florida coast for Hurricane Dennis and Hurricane Ivan. In both stations, model predicted peak elevations match well with observations in both hurricane events. The decomposed storm surge hydrograph also make it possible for analysis potential extreme water levels if storm surge occurs during spring high tide.
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Date Issued: 2007
Identifier: FSU_migr_etd-0416
Format: Thesis

Title: Bio-Reactive Landfill Covers: An Inexpensive Approach to Mitigate Methane Emissions.
Creator: Escoriaza, Sharon Czarina, Abichou, Tarek, Chanton, Jeff, Chan-Hilton, Amy, Powelson, Dave, Department of Civil and Environmental Engineering, Florida State University
Abstract/Description: Methane is one of two primary gases produced from the decomposition of landfill waste. Studies have been directed to collection and mitigation of methane gas. In small landfills, collection is not an economically feasible solution. Bio-cover placement is an inexpensive approach to mitigating methane emissions. The enhancing of oxidation processes by placement of bio-covers will reduce emissions even while gas extraction is employed and improve aesthetic quality of solid waste facilities. The...
Show moreMethane is one of two primary gases produced from the decomposition of landfill waste. Studies have been directed to collection and mitigation of methane gas. In small landfills, collection is not an economically feasible solution. Bio-cover placement is an inexpensive approach to mitigating methane emissions. The enhancing of oxidation processes by placement of bio-covers will reduce emissions even while gas extraction is employed and improve aesthetic quality of solid waste facilities. The overall objective of the research is to mitigate methane emissions from landfills. To reach this objective, a test site was selected to evaluate the effects of compost placement over a closed landfill. The static chamber technique was used to estimate methane emissions and the stable isotope tracing method was used to determine oxidation rates. Hot spots were identified in the grid area and emissions at these spots were analyzed more in detail. Results obtained during the first year of the study are presented in this thesis. In these investigative efforts, it was noted that moisture content plays a significant role in controlling emissions and oxidation. At high water contents, low flux emissions were measured observed and at low water contents, emissions were higher. Oxidation rates varied in much the same way. High water contents corresponded with low oxidation rates and vise versa. Further study on the effects of moisture content and other variables on flux emission and oxidation is warranted.
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Date Issued: 2005
Identifier: FSU_migr_etd-0520
Format: Thesis

Title: An Investigation of Methods to Reduce Hydrogen Sulfide Emissions from Landfills.
Creator: Anunsen, Sarah, Abichou, Tarek, Chanton, Jeffery, Tawfiq, Kamal S., Department of Civil and Environmental Engineering, Florida State University
Abstract/Description: Odors from landfills are a major concern for landfill operators and management of odor will become an increasing concern as landfills that were once constructed in remote areas are being encroached upon by growth. Landfills generate a large volume of landfill gas. Large landfills are required to have gas control systems that pull the landfill gas from the landfill and create energy or combust it with a flare. Landfill gas control is the most effective method to control odors. Many smaller,...
Show moreOdors from landfills are a major concern for landfill operators and management of odor will become an increasing concern as landfills that were once constructed in remote areas are being encroached upon by growth. Landfills generate a large volume of landfill gas. Large landfills are required to have gas control systems that pull the landfill gas from the landfill and create energy or combust it with a flare. Landfill gas control is the most effective method to control odors. Many smaller, older landfills are exempt from gas control regulations. This study investigates methods of odor control for these landfill applications The focus of this study investigates the ability of M1 steel, a by-product from shredded tires, iron rich soil, wood mulch, and compost to attenuate odor of landfill gas. The materials were investigated in filters connected to a landfill gas vent; the landfill gas flow rate was controlled to quantify the reduction. Landfill gas samples were collected before and after the filter and analyzed using gas chromatography to compare the concentration reduction of H2S across the filter. The results of this study provide an analysis of the performance of the media and presents design scenarios to reduce odors at smaller or older landfills. The design scenarios provide performance life of passive landfill vent filters using the M1 Steel and landfill cover applications using red soil, wood mulch, and compost.
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Date Issued: 2007
Identifier: FSU_migr_etd-0223
Format: Thesis

Title: The Effect of High Groundwater Level on Pavement Subgrade Performance.
Creator: Zhang, Chaohan, Ping, W. Virgil, Niu, Xufeng, Hilton, Amy Chan, Abichou, Tarek, Abdullah, Makola, Department of Civil and Environmental Engineering, Florida State University
Abstract/Description: High groundwater table exerts detrimental effects on the roadway base and the whole pavement. Base clearance guidelines have been developed to prevent water from entering the pavement system in order to reduce its detrimental effects. This dissertation presents an experimental study to evaluate the effects of high groundwater and the moisture on determining pavement base clearance for granular subgrades. Full-scale in-lab and test-pit tests were conducted to simulate pavement profile and...
Show moreHigh groundwater table exerts detrimental effects on the roadway base and the whole pavement. Base clearance guidelines have been developed to prevent water from entering the pavement system in order to reduce its detrimental effects. This dissertation presents an experimental study to evaluate the effects of high groundwater and the moisture on determining pavement base clearance for granular subgrades. Full-scale in-lab and test-pit tests were conducted to simulate pavement profile and vehicle dynamic impact on the pavement. Eight types of granular subgrades were tested for this study. From the test, using layer theory, the results of the resilient modulus for each layer (layer resilient modulus) can be compared with the resilient modulus results from laboratory test. Multiple regression model will be established to predict soil resilient modulus without doing resilient modulus test. The dominant factor or factors of the effect of moisture to resilient modulus will be discussed. The results showed that a 24-inch base clearance was considered adequate for the base protection of most A-3 and A-2 subgrades against high groundwater tables. The lab resilient modulus and layer resilient modulus have the same trend for each soil according to the moisture content change. The SR-70 A-2-4 (14% fines) soil was the most susceptible to the change of groundwater table than the other soils. The percent of fines or the percent of clays of subgrade soil is not good indicator to measure the influence of moisture effect on the resilient modulus. The coefficient of uniformity and coefficient of curvature of the subgrade gradations, which better represent the whole shape of the gradation curve, are better indicators of the effect of moisture to modulus.
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Date Issued: 2004
Identifier: FSU_migr_etd-0545
Format: Thesis

Title: Design of Cost Effective Lysimeter for Field Evaluation of Alternative Landfill Cover Projects Using HYDRYS 2D Simulation.
Creator: Liu, Xiaoli, Abichou, Tarek, Hilton, Amy Chan, Tawfiq, Kamal, Department of Civil and Environmental Engineering, Florida State University
Abstract/Description: Landfills are the most widely used facilities for solid waste disposal. Landfill covers are used to reduce the quantity of water that infiltrates into solid waste landfills, isolate solid waste from the environment and control gas migration. Resource Conservation and Recovery Act (RCRA) regulations prescribe that the covers employ layers which have low saturated hydraulic conductivity as hydraulic barriers. Those barriers can limit flow into underlying solid wastes, and consequently, reduce...
Show moreLandfills are the most widely used facilities for solid waste disposal. Landfill covers are used to reduce the quantity of water that infiltrates into solid waste landfills, isolate solid waste from the environment and control gas migration. Resource Conservation and Recovery Act (RCRA) regulations prescribe that the covers employ layers which have low saturated hydraulic conductivity as hydraulic barriers. Those barriers can limit flow into underlying solid wastes, and consequently, reduce the rate of leachate generation and risk of additional groundwater contamination. Experience has shown that the prescribed clay barrier layers are susceptible to failure caused by desiccation and cracking damage by freeze â thaw actions, and are expensive to build. An effective alternative cover design is Evapor-Transpiration (ET) cover. ET covers possess many advantages over prescribed covers such as working with nature, long life time, easy maintenance and lower cost. Once the feasibility of an ET cover is verified in a region, an evaluation of hydraulic equivalency is required for alternative cover to be approved by regulatory authorities. The hydraulic equivalency requires that percolation from the base of the alternative cover is less than or equal to percolation rate from the prescriptive cover. Lysimeters was suggested to be used in facilities measuring the percolation rate. There are some concerns about the precision with which percolation rate can be measured with lysimeters. A series of numerical simulations were performed in this study to investigate the performance of lysimeters of various geometries and develop the optimal lysimeters dimensions for percolation rate measurement. The simulations consist of inputting data for lysimeter geometry, soil hydraulic property, weather condition, boundary condition, vegetation distribution and density. The output cumulative flux data was used to evaluate the performance of lysimeters. The study shows at the specific weather condition, the lysimeters without sidewalls underestimate percolation rate by at least 25%. Installation of full sidewalls remarkably improved the lysimeter performance. The lysimeter with full scale sidewalls still underestimate by at least 10%. Lateral diversion and no-flow boundary at the bottom of lysimeter and the drainage layer right above the bottom pan caused the decrement of lysimeter performance. To measure percolation rate accurately, soil - specific and site - specific coefficients have to be determined. The coefficients can to be used to correct lysimeter performance.
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Date Issued: 2004
Identifier: FSU_migr_etd-1198
Format: Thesis

Title: Environmental Sustainability of Ethanol Production Using the Lifecycle Analysis Method.
Creator: Toliver, Tiffany L, Abichou, Tarek, Chan-Hilton, Amy, Chen, Gang, Tawfiq, Kamal, Department of Civil and Environmental Engineering, Florida State University
Abstract/Description: Ethanol is a controversial source of alternative fuel. In the United States ethanol is produced predominantly from corn and has made headlines as a popular green energy, driven both politically and geographically. Green energy is defined as an energy that has little or no negative environmental impacts. The purpose of this study is to determine if ethanol is really a green energy. This determination can be made by quantifying the greenhouse gas emissions produced by ethanol production using...
Show moreEthanol is a controversial source of alternative fuel. In the United States ethanol is produced predominantly from corn and has made headlines as a popular green energy, driven both politically and geographically. Green energy is defined as an energy that has little or no negative environmental impacts. The purpose of this study is to determine if ethanol is really a green energy. This determination can be made by quantifying the greenhouse gas emissions produced by ethanol production using the LCA (Life Cycle Assessment) method of analysis. Using equivalent units, carbon dioxide emissions can be quantified and compared to other sources of alternative energies. Carbon footprinting is mainly used to understand the impacts humans have individually and as a mass on the environment. It can be computed and expressed as a quantity towards the computation of greenhouse gas contribution. In the case of ethanol, a carbon footprint can be developed by looking at the physical life cycle of a kernel of corn, cane of sugar or bushel of switchgrass. Comprehensively, the ethanol life cycle can be divided into four main parameters. The first parameter is feedstock, followed by technology, third is capital and the final parameter is off take. While each parameter is singularly important, this study focuses on greenhouse gas emissions. It was determined that in comparison, corn ethanol greenhouse gas emissions far exceed the greenhouse gas emission of both sugarcane and switchgrass (cellulosic) ethanol for any case. In the case where LCA is carried through distribution and use of ethanol, sugarcane ethanol is the less greenhouse gas emissive. In the case where the LCA stops at ethanol production, switchgrass is the less greenhouse gas emissive. It is important to note, however, that switchgrass (cellulosic) ethanol is in its infancy as of this writing and data provided is largely projected on the part of the respective researcher.
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Date Issued: 2008
Identifier: FSU_migr_etd-1287
Format: Thesis

Title: Numerical Simulations of Nutrient Removal by Slow-Rate Wastewater Irrigation and Conventional Septic Systems.
Creator: Harmon, Virginia P., Abichou, Tarek, Hilton, Amy Chan, Chen, Gang, Department of Civil and Environmental Engineering, Florida State University
Abstract/Description: Land application is one of the natural treatment processes for raw or partially treated domestic wastewater. Examples include application of septic tank effluent to soil for subsurface infiltration, slow-rate (SR) wastewater irrigation, overland flow wastewater application, and soil aquifer treatment (SAT), also called rapid infiltration (RI). These processes can remove nitrogen, which usually is the limiting design parameter for a land application system. Wastewater or septic tank effluent...
Show moreLand application is one of the natural treatment processes for raw or partially treated domestic wastewater. Examples include application of septic tank effluent to soil for subsurface infiltration, slow-rate (SR) wastewater irrigation, overland flow wastewater application, and soil aquifer treatment (SAT), also called rapid infiltration (RI). These processes can remove nitrogen, which usually is the limiting design parameter for a land application system. Wastewater or septic tank effluent applied to the land in this study contains organic nitrogen and ammonia, plus nitrate and nitrite in the wastewater. In this study, HYDRUS-1D software, version 3.0, was used to conduct numerical simulations of one-dimensional water flow and nitrogen transport in vertical profiles of unsaturated soil to simulate the following scenarios: 1) slow-rate wastewater irrigation and 2) the application of septic tank effluent to soil for subsurface infiltration. The total depth of each soil profile was 300 cm with one soil type (Kershaw Sand) in each profile. The slow-rate simulation profiles consisted only of soil; the septic simulation profiles contained a total of 270 cm of soil with a 30 cm space containing drainrock (no effect on simulation) around the effluent distribution pipe. It was assumed that all applied nitrogen was converted to nitrate within the same time period assumed for application, and that there was no adsorption of nitrate. Water balance outputs included cumulative transpiration, hydraulic flux across the bottom of the soil profile, evaporation, infiltration, and runoff per square centimeter of soil. Nitrogen balance outputs included cumulative amount of nitrate removed by denitrification, root nitrate uptake, and nitrogen flux across the bottom of the soil profile. In the slow-rate simulations 4.30 mg N per cm2 of soil surface was applied per year, and 96.0% of the applied nitrogen (4.13 mg per cm2) was removed by denitrification and root uptake. In the septic simulation, 50.5 mg N per cm2 of soil surface was applied per year for subsurface infiltration, and 63.6% of the applied nitrogen (32.1 mg/cm2) was removed by denitrification. The objective of this study was to compare the nutrient loading from two hypothetical nitrogen contributors to the environment analogous to, and with only a general resemblance to, 1) the City of Tallahassee Southeast Farm (SEF), which practices SR wastewater irrigation and 2) conventional septic systems. The modeling conditions for each contributor were set to be as similar as possible to those for the other contributor. Flux results from the above simulations (per square centimeter of soil during the second year of the simulation) were multiplied by appropriate factors to yield the total mass of nitrogen applied to the surfaces of and the total mass of nitrate exiting the bottoms of the 300-cm soil profiles for sources 1) and 2) during one year. The estimated total mass of nitrogen applied to the simulated Southeast Farm was 3.48 x 105 kg N/yr. The estimated total mass of nitrogen in the effluent from 28,217 septic tanks from conventional septic systems added to drainfields in the unconfined areas of Leon and Wakulla counties and in the semi-confined area of Leon County was 3.56 x 105 kg N/yr. The total mass of nitrogen as nitrate exiting the bottom of the soil profile of the simulated SEF (2,000 acres) was estimated to be 1.67 x 104 kg/yr. The total mass of nitrogen as nitrate exiting the bottoms of the soil profiles for the estimated 28,217 conventional septic systems in the geographical areas listed in the previous paragraph was estimated to be 1.31 x 105 kg/yr. Additional simulations of slow-rate wastewater irrigation were conducted to meet the objective of modeling the nitrogen removal while varying the wastewater loading rate and the denitrification rate constant (K). The inputs were chosen so that the nitrate concentration ranged from 0 to 1.6 mg/L N as nitrate in plots of simulated nitrate concentrations at the bottom of the soil profile versus wastewater loading rate. When K was 0.038/day, it was possible to maintain a nitrate concentration at the bottom of the soil profile at or below 1.0 mg/L as long as the daily hydraulic wastewater loading was less than or equal to 1.5 cm/day. The corresponding wastewater loading values for K of 0.025/day and K of 0.012/day were about 1.0 cm/day and 0.5 cm/day, respectively. The nitrate concentrations at bottom of soil profile corresponding to the current wastewater loading rate of 0.841 cm/d used for the simulated "Southeast Farm" were approximately 0.65 mg/L for K = 0.025/day and 0.15 mg/L for K = 0.038/day. The results of this study may be usable to compare the yearly amounts of nitrogen loading for the above facilities. However, the overall accuracy of the results in describing the real SEF or a real conventional septic system is low mainly because of the method of modeling denitrification, the simplified method of determining input values, and perhaps the complexity of the processes modeled. Future modeling could be conducted so as to improve upon the above limitations. Also, the simulation(s) could be set up to take into account the effect, if any, of the water table elevation on flow. Further studies are needed to better understand and predict denitrification, and other types of denitrification models are available. At real sites, soils with improved water-holding properties could be added via soil mixing, thus improving wastewater treatment performance.
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Date Issued: 2007
Identifier: FSU_migr_etd-4265
Format: Thesis

Title: Gas Emissions in Landfills.
Creator: Melaouhia, Haykel, Abichou, Tarek, Chanton, Jeffrey M., Tang, Youneng, Tawfiq, Kamal Sulaiman, Chen, Gang, Florida State University, College of Engineering, Department of Civil...
Show moreMelaouhia, Haykel, Abichou, Tarek, Chanton, Jeffrey M., Tang, Youneng, Tawfiq, Kamal Sulaiman, Chen, Gang, Florida State University, College of Engineering, Department of Civil and Environmental Engineering
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Abstract/Description: Environment and natural resources can be polluted and consequently human beings, animals and plants can be impacted. Then, waste management plays an important role in human's life. Landfilling is one of the most common technology for solid waste management (MSW) as an alternative to waste burning and composting. A complex series of biological and chemical reactions is initiated with the burial of solid waste in a landfill, resulting in the production of methane (CH4) and carbon dioxide (CO2)...
Show moreEnvironment and natural resources can be polluted and consequently human beings, animals and plants can be impacted. Then, waste management plays an important role in human's life. Landfilling is one of the most common technology for solid waste management (MSW) as an alternative to waste burning and composting. A complex series of biological and chemical reactions is initiated with the burial of solid waste in a landfill, resulting in the production of methane (CH4) and carbon dioxide (CO2) as the major end products of biological decomposition. With a global warming potential 25 times as high as than carbon dioxide on a century time scale, methane is an important greenhouse gas in the climate system. The fate of this CH4 varies widely depending on typical landfill practice in a specific country. Ideally, all generated CH4 would be captured and used beneficially as an energy source. However, even at modern landfills, some CH4 is released before installation of gas collection systems and some CH4 is released because it is not captured in a collection system. A fraction of the uncollected CH4 is oxidized in the landfill cover through bacterial activities and the rate of CH4 oxidation has recently been reviewed. Thus, estimation of methane emissions from landfills is a crucial task. Several models have been developed through the history for such a task, however, none of them represent the reality of the different phases that methane goes through in the landfill. Moreover, methane oxidation capacity estimation has been only based on stable isotopes method. The objective of this work is to develop new methodologies to quantify methane oxidation capacity within landfill covers and to develop a holistic gas estimation model based on the different phases that gas goes through, generation, collection and oxidation, and this model will be calibrated based on field measurements and historical data available over the United States.
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Date Issued: 2017
Identifier: FSU_2017SP_Melaouhia_fsu_0071E_13859
Format: Thesis

Title: Evaluation of Large Scale Biofilter as a Means of Mitigating Landfill Gas Emissions.
Creator: Tyner, Wade, Abichou, Tarek, Chanton, Jeff, Tawfiq, Kamal S., Department of Civil and Environmental Engineering, Florida State University
Abstract/Description: Methane emissions from solid waste landfills are a significant portion of total anthropogenic greenhouse gas emissions. Present means of dealing with landfill gas emissions are too costly for many old and small landfills where gas generation is too low to justify the expense of active gas collection and/or energy conversion systems. As such, a low cost, low maintenance alternative is sought after to deal with these emissions. This study investigated the possibility of a completely passive gas...
Show moreMethane emissions from solid waste landfills are a significant portion of total anthropogenic greenhouse gas emissions. Present means of dealing with landfill gas emissions are too costly for many old and small landfills where gas generation is too low to justify the expense of active gas collection and/or energy conversion systems. As such, a low cost, low maintenance alternative is sought after to deal with these emissions. This study investigated the possibility of a completely passive gas collection system for redirecting gas flows to biofilters containing naturally occurring methanotrophic bacteria. The collection system consisted of horizontal trenches dug just below the soil cover of the landfill, which were filled with tire chips and perforated pipe in order to direct gas towards the biofilters. The biofilters were wire mesh containers filled with three different compost mixtures, which allowed for oxygen penetration on all sides except for the bottom. In this study, it was found that the hydraulic conductivity of the compacted waste was too low to allow for passive drainage of the trenches following precipitation. This resulted in total blockage of gas flow and a need for active intervention involving the use of bilge pumps to return flow to the biofilters. Overall oxidative performance of the filters was lower in this study than that found for clay covers on the same landfill in previous studies. An increase in oxidative performance was found with decreasing flux and may present the possibility that a similar design tested on older landfills with much lower gas flows would yield much higher oxidation rates.
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Date Issued: 2007
Identifier: FSU_migr_etd-1442
Format: Thesis

Title: Impact of Landfill Leachate on Iron Release from Northwest Florida Iron Rich Soils.
Creator: Subramaniam, Pawan Kumar, Chen, Gang, Hilton, Amy Chan, Abichou, Tarek, Department of Civil and Environmental Engineering, Florida State University
Abstract/Description: Landfill leachate is blamed for elevated levels of iron in the groundwater monitoring wells downgradient of unlined landfills. It is suspected that the geochemical and geomicrobial iron reduction/oxidation processes are responsible for the iron release to the groundwater. When conditions permit, microbial mediated iron reduction and release may be the mechanism for elevated iron observations in the groundwater. In regions near the landfills, there is also a possibility of iron release due to...
Show moreLandfill leachate is blamed for elevated levels of iron in the groundwater monitoring wells downgradient of unlined landfills. It is suspected that the geochemical and geomicrobial iron reduction/oxidation processes are responsible for the iron release to the groundwater. When conditions permit, microbial mediated iron reduction and release may be the mechanism for elevated iron observations in the groundwater. In regions near the landfills, there is also a possibility of iron release due to the oxidation of metallic iron, especially, near the C&D landfills, which can occur under both aerobic and anaerobic conditions. The objective of this research is to investigate whether, and to what extent, microbial activities are responsible for iron release in the regions near landfills in Northwest Florida. For microbial mediated iron reaction processes, we want to testify whether it is an iron reducing process or sulphate reducing process (iron oxidation). In addition, we want to quantify the iron reduction/oxidation rate to provide evidence which mechanism is dominating and responsible for iron release in Northwest Florida. The methodology of this research is to react simulated leachate with soils collected from Northwest Florida in the absence and presence of microbial species cultured from landfill regions where elevated groundwater iron concentrations have been observed. Sixteen landfills of fifteen Northwest Florida counties were sampled and the soil iron content of these samples was quantified. Iron release experiments were then carried out using the sampled soil reacting with leachate samples in the presence of iron reducing bacteria that was pre-cultured using iron rich soil as the base consortia. The variations in pH throughout the experiments were monitored to study the correlation between iron concentration and pH. Iron release was most pronounced for soil samples collected from Walton County Central landfill reacting with the corresponding landfill leachate. The iron release for this site was as high as 275 mg/L within 5 days. On the contrary, minimal iron release was observed for the control, i.e., in the absence of iron reducing bacteria. These observations demonstrated that iron release nearby landfills in Northwest Florida was a microbial mediated iron reduction process. Though this research is focused on Northwest Florida, the results of this research can be applied beyond local perspectives to any region with iron rich soils.
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Date Issued: 2007
Identifier: FSU_migr_etd-1519
Format: Thesis

Title: Impact of Lipopolysaccharide Extraction on Bacterial Transport.
Creator: Rangachar, Vijay Penagonda Srinivasa, Chen, Gang, Hilton, Amy Chan, Abichou, Tarek, Department of Civil and Environmental Engineering, Florida State University
Abstract/Description: Increasing water demands owing to the growth of urbanized populations have led to constraints on existing surface and groundwater supplies. Reclaimed wastewater thus has the potential to be used for agricultural irrigation. During the practice of reclaimed wastewater reuse, special care must be taken to monitor the fate and transport of the infectious agents or pathogenic organisms existing in the reclaimed wastewater since they may pass through the vadose zone and contaminate the groundwater...
Show moreIncreasing water demands owing to the growth of urbanized populations have led to constraints on existing surface and groundwater supplies. Reclaimed wastewater thus has the potential to be used for agricultural irrigation. During the practice of reclaimed wastewater reuse, special care must be taken to monitor the fate and transport of the infectious agents or pathogenic organisms existing in the reclaimed wastewater since they may pass through the vadose zone and contaminate the groundwater. It is hypothesized lipopolysaccharide extraction would enhance bacterial interactions with the porous media, resulting maximum retention of the strains in the soil. Thus reclaimed wastewater can be recommended to go through relevant treatment process to remove bacterial lipopolysaccharide before it is practiced for agricultural irrigation. Lab cultured gram-negative bacterial strains, Escherichia coli, Pseudomonas aeruginosa and Pseudomonas fluorescens were used in the research. Lipopolysaccharide of these strains was extracted and column experiments were then conducted for both treated and untreated bacterial strains with silica sand serving as the porous media. Transport of these strains was described by the equilibrium-kinetic two-region solute transport model by fitting the experimentally obtained bacterial breakthrough data using CXTFIT 2.1. Bacteria were retained in the media during transport for all the three strains with or without lipopolysaccharide extraction. Observations after lipopolysaccharide extraction showed greater retention for all the strains as compared to the original strains, indicating enhanced bacterial interaction within the media. Electrostatic interations between bacterial strains and porous media were calculated based on the measured zeta potential values of the strains and the media. It was found that bacterial deposition coefficient linearly decreased with the increase of the electrostatic interactions. After lipopolysaccharide extraction, bacterial electrostatic interactions with the porous media.
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Date Issued: 2007
Identifier: FSU_migr_etd-2043
Format: Thesis

Title: Mitigation of Landfill Methane Emissions from Passive Vents by Use of Oxidizing Biofilters.
Creator: Morales, Jose J., Abichou, Tarek, Chanton, Jeff, Hilton, Amy B. Chan, Tawfiq, Kamal S., Department of Civil and Environmental Engineering, Florida State University
Abstract/Description: Decay of waste within landfills is a contributing source to the greenhouse effect due to the production of methane. Larger landfills tend to have gas collection systems, which collect and convert gas into energy or flare it. Older and smaller landfills, however, usually vent this greenhouse gas into the atmosphere through passive vents. This study focuses on the attenuation of methane gas from these passive vents through the use of biofilters containing methanotrophic bacteria. These...
Show moreDecay of waste within landfills is a contributing source to the greenhouse effect due to the production of methane. Larger landfills tend to have gas collection systems, which collect and convert gas into energy or flare it. Older and smaller landfills, however, usually vent this greenhouse gas into the atmosphere through passive vents. This study focuses on the attenuation of methane gas from these passive vents through the use of biofilters containing methanotrophic bacteria. These methanotrophic bacteria can oxidize methane into carbon dioxide, water, and biomass. Two biofilter designs were explored in this study. The vertical biofilter design has a methane inflow near the bottom which emits the methane upward through the filter medium in which the methanotrophic bacteria reside. The radial biofilter design has a methane inflow source imbedded in the center, vertically, in the filter medium, which emits the methane horizontally. The purpose of the radial design was to increase methane oxidation by increasing the surface area, thus increasing oxygen penetration. The surface area of the radial design was 1.212 m2 compared to 0.264 m2 of the vertical filter design. Biofilter surface area proved to be a factor in the oxidation of passively vented landfill methane. Although the two filter designs achieved a similar oxidation average for the study period, the radial biofilter design obtained a much higher removal rate at a higher input than that of the vertical design. The better performance of the radial biofilters was due to greater oxygen penetration as verified by probe gas profiles. This increase in oxygen penetration was directly linked to the larger surface area, which had a lower influx than that of the smaller surface area of the vertical design when having the same methane input. This study also tested the use of two different biofilter media mixtures for oxidizing methane. The mixtures were a combination of recycled tire chips and compost, and a combination of peanut packing foam and compost. The purpose of mixing the compost with the tire chips or the peanut foam was to hopefully increase oxygen penetration and thus, methane oxidation. The study proved that there was statistically no difference in performance between the two media types. Averages of the study period showed a nearly equal methane oxidation average and methane removal rate. Air temperature, media temperature, and barometric pressure were recorded during testing events for the period of this study. There was an increase in average air temperature through out the study (this was due to a change in seasons, from winter to summer). Average methane outputs from the passive vents studied showed a decreasing pattern throughout the study. This decrease in methane output is due to a decrease in anaerobic decomposition because of the old age of the waste in the section of the landfill studied. It was concluded that there was a direct correlation between biofilter media temperature and methane oxidation by the methanotrophic bacteria. Average oxidation rates of 20% and higher were all within the range of 20-36°C. This temperature range agrees with published research (Visvanathan et al., 1999) that states that this is the optimal soil temperature for methanotrophs to oxidize methane. There was no direct correlation found between atmospheric pressure and landfill methane emissions from passive vents. This research established that the radial filter design was superior to that of the vertical design for methane oxidation. However, it is important to note that what led the radial design to have a superior performance over that of the vertical design was its increased oxygen penetration and lowered influx of gases due to its larger surface area. Thus, further research of these factors is imperative to ultimately making biofilters viable option for mitigating methane emissions from passively vented landfills.
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Date Issued: 2006
Identifier: FSU_migr_etd-2276
Format: Thesis

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