The occurrence of temperatures in municipal solid waste (MSW) landfill gas (LFG) extraction systems in excess of 55°C is a problem that has gained much attention in the solid waste industry, both domestically and globally. Facilities which frequently experience such temperatures are termed Elevated Temperature Landfills (ETLFs), and recent research conducted at the University of Central Florida (UCF) has provided strong evidence that ash, both MSW incinerator ash (MSWIA) and coal combustion ash (CCA), when co-disposed with unburned MSW, provides materials which are able to participate in abiotic exothermic reactions that may lead to the development or sustainment of ETLFs. These reactions include ash hydration and carbonation, as well as the oxidation and corrosion of metals commonly found in ash. Over the course of this project, sixteen ash samples from across the U.S. were analyzed (ten MSWIAs and six CCAs) using spectroscopic and thermal analyses. X-ray diffraction (XRD), x-ray fluorescence (XRF), and scanning electron microscopy coupled with x-ray dispersive elemental spectroscopy (SEM/XEDS) provided insight into ash compositions, while thermal gravimetric analysis (TGA) shed light into the sensitivity of ashes to changes in temperature. Results from this project reveal that the high-temperature incineration of MSW and coal feedstocks, as well as weathering processes impacting these ashes, yields a heterogenous material with many complex mineral and glassy phases. A simple heat-generation equation was developed and, using ash compositions obtained via XEDS, a value termed relative heat potential (RHP) was calculated for each sample. Results show that CCAs may be expected to generate roughly 15% more heat than MSWIAs when deposited in landfills, likely due to their greater aluminum content.

An investigation of 1,4-dioxane and enantiomeric ibuprofen mass transfer in a nanofiltration (NF) membrane process has been completed. Pilot-scale experiments using a 267 gallon per minute (gpm) split-feed, center-port NF process treating pH 6.5 groundwater revealed a consistent 12 percent removal of 1,4-dioxane despite the variable feed concentration (180 nanograms per liter (ng/L) to 38,400 ng/L) when the water flux and temperature were held constant. Bench-scale, flat-sheet NF membrane experiments treating pH 4.0 synthetic water displayed a 34.5 to 49.5 percent removal of racemic ibuprofen. Removal values were dependent on feedwater concentration (1 to 1,500 microgram per liter (µg/L)), pH, pressure, and water matrix. Although 1,4-dioxane was not found to exhibit adsorptive tendencies, as much as 25 percent of racemic ibuprofen adsorbed onto the metal surfaces of the testing equipment. Mass balances determined that ibuprofen's S-enantiomer was primarily responsible for the adsorption. Density functional theory (DFT) computations exposed a 6.4 cubic angstroms (Å3) smaller molecular volume and 1.10 x 10-29 coulomb-meters (Debye) longer dipole moment of S-ibuprofen than R-ibuprofen, which could explain the S-enantiomers stronger affinity to stainless-steel equipment components. The rejection of S-ibuprofen was consistently greater than R-ibuprofen, postulated by the dissimilar polarity of the two molecules outlined by DFT calculations. Feedwater ibuprofen concentration, pH, and operating pressure affected ibuprofen adsorption onto the equipment and membrane components. Contact angle measurements revealed a direct relationship between membrane hydrophobicity and adsorbed ibuprofen concentration. Langmuir and Freundlich isotherms accurately modeled S-ibuprofen adsorption. Therefore, at least 24 hours of equilibration is required prior to conducting hydrophobic solute membrane rejection studies. Additionally, application of the Homogeneous Solution Diffusion Model (HSDM) was found to provide accurate predictions of 1,4-dioxane and R-ibuprofen permeate content based on statistical analysis; however, the model was less predictive for the S-enantiomer due to adsorptive tendencies of the molecule.

Cultivation of algae biomass is a promising way to produce animal feeds and biofuels with a lower carbon footprint. Nevertheless, challenges remain before algal products can be commercialized. The high cost of algae cultivation is the primary impediment, and the present study addressed some of the major factors in this cost including: the efficiency of algal utilization of supplemental inorganic carbon such as carbon dioxide from flue gases; algal productivity; the energy use and effectiveness of pond mixing; and biomass harvesting and processing. This dissertation addresses these issues with (1) a literature review of algal carbon utilization, (2) a pilot-scale productivity and culture stability comparison of ten filamentous algal cultures including two local isolates, two polycultures, and six culture collection monocultures, (3) a hydraulic characterization of a full-scale wastewater treatment system with 13,200-15,000 m2 paddlewheel-mixed raceways, and (4) a bench-scale characterization of harvesting, dewatering, and drying of filamentous algae. The review of carbon utilization led to the conclusion that significant research is still needed at large-scale to demonstrate and maximize algal carbon utilization in paddlewheel-mixed ponds. In the algal culture study, a single locally–prospected monoculture of Tribonema minus exceeded productivity of the culture collection monocultures and one polyculture. In the hydraulic study the wire-to-water energy efficiency was 10-15% while mixing was low, indicating that this is an area for improvement. Despite this, the energy used for wastewater treatment was ~76% less than activated sludge. Finally, over 95% of filamentous algal biomass could be harvested by screening, and dewatering to 20% total solids was demonstrated using 75-55 µm mesh screens and a 1500-RPM dewatering device. This research advances understanding in several key gap-areas of algae biology and engineering.

Improved bilgewater treatment is necessary because of technological challenges often faced when meeting existing ocean discharge criteria regulations. Since bilgewater is a waste mixture including hydraulic oils, cleaning agents, and seawater, the success of its management is largely attributed to understanding oil-in-water emulsion characterizations. However, the study of bilgewater emulsions is complex due to the multivariate nature of real-shipboard samples. The objective of this study is to develop the relationship between parameters commonly found in bilgewater and emulsion stability. This work is a continuation of a 3-year research project supported by the Strategic Environmental Research and Development Program (SERDP). Previous research (Year 1–2) identified the governing parameters (salinity, suspended solids, pH, and temperature) for oil-in-water emulsion formation and separation using different model surfactants and commercial cleaners. An emulsion stability model with random forest regression and classification algorithms was developed using data from the previous study. This study focused on expanding the database of emulsion stability levels typically encountered in bilgewater. Four surfactants and cleaners were downselected among a list of commonly used products found in bilgewater on Armed Forces vessels. The effects of determining a surfactant's critical micelle concentration in the presence of a representative bilge oil mix, as well as the contribution of surfactant concentration and homogenization intensity on emulsion stability was investigated. Additionally, the effect of a range of environmental parameters (salinity and suspended solids) was evaluated. The work herein added to the range of available emulsion stability model input characterizations. Via nondestructive analytical methods and statistical evaluation, it was found that surfactant concentration, homogenization intensity, and salinity had a significant impact on emulsion stability. However, the newly added data representing more realistic conditions did not contribute to the emulsion stability prediction model, while adding extended interval ranges for each factor did improve the accuracy of predictions.

An investigation has been completed that assessed the efficiency of tray and spray aeration processes on the removal of regulated total trihalomethanes (TTHMs) at two publicly owned potable groundwater treatment facilities located in Polk County, Florida: the Providence and Van Fleet water treatment plants (WTPs). Finished water from each of these facilities was fed to a pilot-plant that could be operated as either a tray, spray, or combined configuration. A series of four pilot aerator configurations were tested at each WTP. Test 1 evaluated the tray aerator operated in a recirculated multiple-pass mode. It was shown that three passes across the same tray aerator configuration was effective in reducing 96-hour TTHM formation by 48% and 63% at the Providence and Van Fleet WTPs, respectively. Test 2 (a) measured the effect of increased tray surface area on TTHM reduction. It was shown that increasing the tray aerator surface area by 40% decreased the 96-hour TTHM formation at the Providence and Van Fleet WTPs by 25% and 66%, respectively. Test 2 (b) evaluated the effectiveness of spray aeration on TTHM reduction, resulting in a decrease of 14% in the 96-hour TTHM concentrations at both WTPs. Test 2 (c) combined tray and spray aeration integrated with an increased tray surface area. A 22% and 25% decrease in 96-hour TTHM concentrations was observed with this combined configuration at the Providence and Van Fleet WTPs, respectively. The five regulated haloacetic acid (HAA5) disinfection by-product concentrations were found to be largely unaffected by aeration. Results of this study indicated that the implementation of more surface area within the existing tray aeration units would reduce 96-hour TTHM formation concentrations. The addition of a recirculation pump would aid in reducing 96-hour TTHM formation but could be limited by the operation of the ground storage tank at each site.

This research investigated the use of seawater regeneration for anion exchange (AIX) processes. Seawater and salt-supplemented seawater regeneration of chloride-form anion resin were evaluated in regard to (1) operational performance efficiency of sulfate and natural organic matter removal, (2) competing exchange of bromide during regeneration, and (3) brominated disinfection by-product (DBP) formation due to bromide leakage. The first component involved bench-scale research that revealed that seawater-based regeneration led to bromide leakage that could be mitigated to an average of 1.82 mg/L using 1% salt-supplemented seawater, and 1.25 mg/L using 3% salt-supplemented seawater. Conceptual cost comparisons revealed that the use of seawater can reduce regeneration costs by up to $0.25/kgal compared to conventional 10% salt. The second segment of research demonstrated that bromide adsorption in the presence of chloride followed pseudo 2nd order kinetics. Increasing the chloride-to-bromide ratio shifted intra-particle diffusion that revealed an exponential decay in bromide adsorption capacity. The equilibrium adsorption behavior could be described by both Freundlich and Langmuir isotherm models. The third segment of research evaluated the impacts of bromide leakage with respect to DBP formation. Results demonstrated that the 96-hr formation potential for total trihalomethanes (TTHMs) increased from 186 ug/L to 294 ug/L and haloacetic acids (HAA5) from 25.7 ug/L to 36.1 ug/L for a subsequent increase in bromide content from 0.22 mg/L to 2.13 mg/L, respectively, with a noticeable shift in chemical speciation from chlorinated to brominated forms. Coastal water utilities employing AIX might consider salt-supplemented seawater regeneration methods; however, further research is needed to confirm the long-term performance effects of this technique.

A pilot investigation that compared ozone oxidation with an integrated ozone and granular activated carbon (GAC) process for the control of regulated disinfection by-products at the University of Central Florida's water plant located at the Orlando campus has been completed. Treatment effectiveness was measured by monitoring the parameters pH, temperature, non-purgeable dissolved organic carbon (DOC), ultraviolet absorbance at a wavelength of 254 nm (UV254), specific ultraviolet absorbance (SUVA), excitation emission matrices (EEMs) and the associated formation of the DBP chemical groups total trihalomethanes (TTHMs) and haloacetic acids (HAAs). Groundwater that contained an average of 2.5 milligrams per liter (mg/L) DOC and 0.8 mg/L total sulfide was fed to a 15 gram/hour ozone contactor prior to being transferred to two parallel GAC pilot columns, each containing a different coal-based GAC material, either denoted Filtrasorb® (FS-400) or HPC-830 (HPC-830), with an apparent density of 0.54 and 0.36 grams per cubic centimeter, respectively. Stand-alone ozone treatment having an instantaneous ozone demand of 0.82 mg/L O3 provided a 6.0 mg/L O3 residual that when held for 30 minutes, followed by the addition of 5 mg/L Cl2 to represent disinfection, reduced 48-hour TTHM formation by 22 percent, however, increased 48-hour HAA formation by 67 percent. The integrated ozone-GAC process was found to consistently reduce 24-hour and 48-hour TTHM and HAA formation to below regulatory levels through the entirety of the 420 hours of operational run-time. Results for the integrated ozone-GAC process operating at a dose of 7.20 mg/L O3 both FS-400 and HPC-830 carbon types reached an average of 60% breakthrough for UV254 and DOC in the last 1000 bed volumes of the study. Projections with these results provided an estimated 30,000 EBV and 35,000 EBV for the FS-400 and HPC-830 carbon types, respectively, and could be achieved prior to bed DOC exhaustion.

This research attempted to leverage the unique properties of poly (allylamine hydrochloride) (PAH)/poly (acrylic acid) (PAA) bilayer coatings to enhance antifouling and antimicrobial properties of a commercially available ultrafiltration (UF) membrane as well as the removal of PFOA and PFOS—the two CECs that most frequently represent the class of PFAS. The effects of selected water matrix components (humic acids [HA] and cations) on PFOA and PFOS removals were also investigated when using the functionalized membrane. PAH/PAA films were first deposited on the membrane using a fluidic layer by layer (LbL) technique and then crosslinked, followed by embedding of the silver phosphate nanoparticles (AgPNPs) within the PE coatings. Microprofile measurements using a solid contact Ag micro-(ion-selective electrode) ISE as well as post-filtration an inductively coupled plasma (ICP) analysis demonstrated that AgPNP were effectively immobilized within the crosslinked PAH/PAA bilayers. The PAH/PAA functionalization imparted enhancements in membrane properties including surface charge and hydrophilicity and rendered a smoother membrane surface. Upon stable and uniform deposition of PAH/PAA "bilayer" (BL) coatings, the permeate flux was governed by both PAH/PAA-derived hydrophilicity and surface/pore coverage. Membrane porosity and MWCO were reduced by approximately 9% and 38%, respectively. It was observed that an optimum number of bilayers must be applied to ensure that the resulting permeability is not offset by the hindrance from the deposition of bilayers. Furthermore, membrane functionalization rendered antimicrobial property as indicated by less attachment of bacteria that would have initiated the formation of biofilms leading to biofouling. When compared to the unmodified membrane, PFOA and PFOS removals while using the modified UF membrane increased from 20 to 50% and from 22 to 52%, respectively. The approximately 30% higher removal of both PFOA and PFOS may be attributed to the size exclusion mechanism. While the presence of only HA did not influence the removal of PFOA and PFOS significantly, the coexistence of HA and cations in water resulted in significant increase in the rejection of both the PFASs. This can be attributed to the enhanced size exclusion of the complexes that PFOS and PFOA may form with HA and cations in the source water.

This document details the source and occurrence of particulates in a nanofiltration (NF) process, considers the implementation of additional pretreatment to improve feedwater quality, and investigates the impact of submicron particles on membrane performance. Much of this research was performed in cooperation with the City of Boynton Beach (City) at the West Water Treatment Plant (WTP) and stemmed from particulate fouling concerns in the pretreatment and NF membrane processes. The water quality of the individual wells that supply the West WTP was evaluated to identify the source of particulates which overload the pre-filters (5-μm cartridge filters) and may contribute to membrane fouling. The results indicated that particulates are largely provided by three of the ten wells; however, it was shown that the wells produced poor quality supplies upon well start-up containing increased turbidity relative to the membrane feedwater quality. The effectiveness of sand filtration (SF) as an additional pretreatment step, prior to CF, was investigated in a pilot-scale study. SF consistently reduced feedwater turbidity by at least 70 percent. Furthermore, the distribution of nanoparticles (NPs) and microparticles (MPs) in the NF feed-concentrate channel ranged between 50-nm and 70-μm as identified using particle sizing technologies. Over 65 million submicron particles per milliliter (mL) were detected in the feedwater and diminished to approximately 3.5 million particles/mL in the concentrate stream. Most of the particles had diameters of less than 1-μm, while larger MPs were also identified primarily consisting of silts/clays, calcium carbonate, elemental sulfur, and, in the concentrate streams, organic based matter. The impact of NPs on membrane productivity was probed in laboratory-scale experiments. Small NPs (10-20 nm) caused the greatest flux decline; however, when combined with larger particles (1-μm), the flux decline was not as severe likely due to the formation of a lower density foulant layer on the membrane surface.

Temperature aware chip designs have gained importance and popularity in recent years. In this dissertation, we present several temperature aware techniques to reduce the temperature of the chip, to speedup thermal simulations, and to provide live thermal measurements in microprocessors. They include: (1) Temperature aware floorplanning: reducing the maximum temperature of the CPU chip through floorplanning. Through careful block placement, temperature aware floorplanning is able to greatly improve the temperature distribution of the chip while maintaining comparable performance. Experimental results show that it is possible to find a floorplan that can reduce the maximum temperature of a chip by up to 21°C compared to the original floorplan while keeping the total wire length of the chip almost the same as before. (2) Fast architecture-level thermal simulation: utilizing some specific properties of the input power trace to accelerate architecture-level transient thermal simulations. Based on a linear thermal system formulation, the new method replaces many time-consuming integration computations with more efficient matrix multiplications. Experimental results show that the new method provides a speedup of up to 1000x without any accuracy loss compared to the HotSpot simulator. (3) Lightweight runtime temperature monitoring: using internal performance counters to provide detailed temperature distribution information for a CPU chip with negligible overhead. After calibration against a temperature sensor inside the CPU chip, the average temperature deviation is less than 2°C for the SPEC2000 benchmarks, showing that our tool is able to estimate the temperature distribution of a CPU chip with acceptable accuracy.