Master of Science, The Ohio State University, 2017, Food, Agricultural and Biological Engineering

In the food and beverage industry, fouling of food contact surface during thermal process has direct impact on performance and efficiency of operations. Relationship between fouling rates under commercial-scale operations and laboratory-scale experiments requires careful consideration. The objectives of this investigation were to develop and evaluate a laboratory-scale system to mimic a commercial-scale processing system, and to propose methods to quantify the rate of fouling on heat exchanger surface. During design and development, two experimental components were identified; stainless-steel coupons for direct measure of fouling residues and a holder to expose multiple coupons during the experimental thermal conditions. During experimental measurements, reconstituted Non Fat Dry Milk (NFDM) solutions were used. Fourteen liters of 20% w/w NFDM solutions were pre-heated and held in a stainless-steel vessel. An immersion heater was installed at the bottom of the vessel to increase and maintain the temperature of the NFDM solutions. A mechanical agitator was used to establish a range of shear rates over the surfaces. Flexible polymer Kapton heaters were attached to the back of each coupon to control the coupon surface temperature. Thermocouple sensors were used to monitor coupon surfaces temperatures during all experiments. In addition, a Computational Fluid Dynamic (CFD) simulation code was created to estimate the wall shear rates on all surfaces that were exposed to the fouling material. The results from the investigation confirmed that the system could be used to collect fouling data as a function of primary commercial operation parameters. The system was used to collect experimental data over a range of temperatures and times. Experiments were conducted at 65°C, 75°C and 85°C and coupons were removed at 30 minutes intervals for a total duration of 120 minutes. Two methods for measurements of fouling (thermal resistance and protein quantification) were invest (open full item for complete abstract)

Committee: Dennis Heldman R. (Advisor); Sudhir Sastry (Committee Member); V. Blasumramaniam M. (Committee Member) Subjects: Agricultural Engineering

Master of Science in Engineering, Youngstown State University, 2012, Department of Mechanical, Industrial and Manufacturing Engineering

As the electrical power demand increases and water resources become more limited, fouling on the air side of Air Cooled Condensers (ACC) is a growing concern. ACC's are widely used as a method to exhaust waste heat from power plants to the environment while using very little water. Generally fouling on the air side is neglected but with wider implementation of ACC, demands need to be considered to maximize efficiency. Air fouling is partially due to the following: pollen, dust, insects, leaves, and large debris. Fouling limits the convection heat transfer coefficient of the condenser and can cause an increase in backpressure to the turbine or incomplete condensing. Either case will result in a decrease in the plant efficiency and power output. The objective of this study was to experimentally and computationally calculate the convection heat transfer coefficient for both a clean and fouled condenser. Bee pollen was selected as the experimental fouling particle, and engineering data for similar particles were used for the computational model in ANSYS Fluent. Both the experimental and computational results have similar trends showing pollen has a negative impact on the heat transfer. The experimental results show between a 15% and 20% reduction in the coefficient of heat transfer while the computational results show between a 6% and 9% reduction. Suggestions for future work are included to further improve upon this research.

Committee: Hazel Marie PhD (Advisor); William Arnold PhD (Committee Member); Hyun Kim PhD (Committee Member) Subjects: Engineering

PhD, University of Cincinnati, 2009, Engineering : Chemical Engineering

Biofouling is a major problem during microfiltration that causes a reduction in filtration flux and an alteration in membrane selectivity over time. Mathematical modeling of fouling behavior plays an important role in the understanding of complex fouling mechanisms. There is growing interest in the use of both asymmetric and composite membranes for microfiltration and ultrafiltration processes. Previous studies indicate that different asymmetric membrane structure has a significant impact on both filtration flux and sieving property. However, most of previous fouling models were developed for homogeneous membranes. The effects of asymmetric membrane structure on fouling behavior remains poorly understood on a fundamental level.A three-mechanism model was first developed to account for both external fouling and internal fouling by combining three classical fouling mechanisms: pore blockage, pore constriction, and cake filtration. Based on this combined fouling model, the relative importance of different fouling mechanisms was investigated. The fouling model accounting for membrane morphology was modified to accommodate asymmetric structure. Asymmetric profiles were described by the spatial variation of permeability in the direction normal to the membrane surface. The model predictions were in good agreement with the experimental results based on various composite membranes indicating that composite membranes with a porous structure in upper layer and relative high resistance in lower layer can efficiently reduce fouling. A-priori estimation of fouling parameters in the combined pore blockage and cake filtration model was proposed to directly relate the fouling parameters with feed characteristics and membrane properties. These works provide important insights into fouling mechanisms during filtration.A network-based fouling model was developed to simulate the fouling processes. In contrast to the fouling models based on the continuum approaches, network modeling is a (open full item for complete abstract)

Committee: Chia Chi Ho PhD (Committee Chair); William Krantz PhD (Committee Member); Rakesh Govind PhD (Committee Member); Peter Panagiotis Smirniotis PhD (Committee Member) Subjects: Chemical Engineering

Master of Science, The Ohio State University, 2023, Food Science and Technology

Fouling refers to the undesirable build-up of residue from a product on a food-contact surface, which has a deleterious effect on process efficiency. Moreover, the subsequent cleaning required is a serious industrial problem. This issue is realized by a number of industrial sectors like pharmaceutical, petroleum, food, and healthcare. On an industrially relevant scale, research pertaining to fouling/cleaning can be labor intensive and can lead to wastage of resources. In the case of new beverage product formulations, there is currently no method that can evaluate response of fouling intensity and cleaning efficiency. However, in recent years, there have been applications of using quartz crystal microbalance with dissipation (QCM-D) as an analytical instrumentation to investigate fouling and cleaning interactions between the fluid components and the processing surface over a wide range of temperatures. Utilization of plant-proteins to produce fortified beverages has been observed, especially pea proteins, in recent years. There is an opportunity for production of a “blended beverage” that has combined proteins from milk and plant-based sources. However, there is limited research that explores the processibility, fouling, and cleaning interactions of these novel beverages on thermal treatment. Hence, in this research multi-scale fouling and cleaning interactions of blended milk-pea protein beverage has been studied using QCM-D and custom-built pilot-scale system. The influence of temperature on fouling and foulant removal of milk/pea protein blends at two temperature ranges: HTST and UHT temperatures was investigated using the high-pressure high-temperature (HPHT) QCM-D. The results of the study indicate that the influence of temperatures during foulant creation and removal of the foulant is important for beverages containing plant proteins. The fouling rate of blends containing pea protein was lower than skim milk at all temperatures and the fouling rate decreased a (open full item for complete abstract)

Committee: Dennis Heldman (Advisor); Rafael Jimenez-Flores (Committee Member); Sudhir Sastry (Committee Member) Subjects: Engineering; Food Science

MS, University of Cincinnati, 2022, Arts and Sciences: Chemistry

Graphene is a unique and versatile material used for electrochemical detection due to its electrocatalytic properties, large surface area, and high conductivity. Despite these properties, the use of graphene-based materials for real-time neurochemical detection is still in its infancy. Prior work has focused on using carbon-fiber microelectrodes for electrochemical detection of neurochemicals with fast-scan cyclic voltammetry (FSCV); however, carbon-fibers can have low sensitivity towards many neurochemicals, is subject to fouling, and can be difficult to chemically functionalize. In this work, we compare the extent to which different functionalities on graphene materials impacts neurochemical detection with FSCV. Specifically, we compare graphene, graphene oxide, and N-doped graphene-modified carbon-fiber microelectrodes. Optimization of material adherence to the carbon fiber surface was shown to provide critical insight into approaches to modifying carbon fiber with graphene-based materials of varying functionalities. Overall, we show that all materials increase dopamine (DA) oxidative peak current by over a 1.5-fold increase, with N-doped graphene providing the best improvements. This work demonstrates the comprehensive comparison of how different functionalizations on graphene-based materials impact detection and provides useful information for the future development of graphene-based sensors.

Committee: Ashley Ross Ph.D. (Committee Member); Jianbing Jiang Ph.D. (Committee Member); Noe Alvarez Ph.D. (Committee Member) Subjects: Analytical Chemistry

Doctor of Philosophy, The Ohio State University, 2022, Food, Agricultural and Biological Engineering

Fouling is the unwanted build-up of material on a surface. Fouling has a negative impact on process efficiency and increases the frequency of cleaning. Significant amounts of water and energy are used during cleaning. Fouling and cleaning scenarios present a major challenge to numerous industrial sectors, including petroleum, food, fast moving consumer goods, and healthcare. This emphasizes the need to understand fundamental mechanisms of fouling and cleaning. Industrially relevant and scientifically rigorous fouling and cleaning studies require pilot-scale equipment and long process times resulting in labor intensive and highly wasteful studies. Furthermore, the food industry currently has no method for predicting the fouling intensity of a new product formulation which is under development. Theses formulations frequently fail due to intense fouling. Thus, both academic and industrial researchers would benefit from a small-scale and versatile system that could be used to predict fouling and cleaning, while limiting the use of expensive and resource-intensive, pilot-scale screening experiments. Recent studies suggest a novel analytical technique, quartz crystal microbalance with dissipation (QCM-D), has the potential to investigate initial interactions between fouling species and a processing surface, yet most QCM-D research is limited ambient temperature applications and simple model fouling solutions. During this research, QCM-D is applied at high-temperature to investigate fouling and cleaning of complex, milk-based fluids. Research Study 1 (Chapter 3) applies QCM-D to illuminate interactions between complex milk fractions and a stainless-steel surface at low-temperatures (25–65 °C) Results support an increase in fouling rates due to electrostatic attractions between negatively charged proteins and a positively charged stainless-steel surface. Research Study 2 (Chapter 4) presents one of the first applications of high-temperature, high-pressure (HPHT) QC (open full item for complete abstract)

Committee: Dennis Heldman (Advisor); Rafael Jimenez-Flores (Committee Member); Jim Rathman (Committee Member); Sudhir Sastry (Committee Member) Subjects: Engineering; Food Science

Doctor of Philosophy, The Ohio State University, 2021, Civil Engineering

The demand for efficient and effective water purification processes encompasses a breadth of industries. As such, a multitude of filtration technologies and unique approaches have been developed. Adoption of an appropriate filtration technology depends on the nature of the water to be treated and the desired finished water quality. The aim of this work was to evaluate a select set of novel membrane filtration technologies and approaches for their efficiency and applicability. Processes evaluated include (1) electrofiltration utilizing a novel inorganic membrane, (2) a couple forward osmosis – membrane distillation for brine treatment, and (3) a novel in-situ ultrasonic self-cleaning membrane. The application of an electrical potential across a membrane during filtration results in unique effects, dependent on the feed water parameters, the membrane properties and system design. Of particular interest is the production of electroosmotic flow. Electroosmotic flow is the movement of water through the membrane, induced by an electrical potential. This effect is independent of transmembrane pressure. This phenomenon appears to be particularly outspoken in dilute acidic and basic aqueous solutions in oxidic membrane structures. Electroosmotic flow, and the associate specific energy consumption, was studied for electrofiltration of acidified DI water with a 2 mm thick high purity α-Al2O3 membrane with a porosity of 35%, and a narrow pore size distribution around 700 nm. It was found that at a temperature of 23°C, a pH of 4 and a pressure difference, Δp, of 15 kPa, the membrane flux increased from 3.7×10-9 to 5.2×10-9 m/s (59 to 82 LMH) after application of a voltage, ΔΦ, of 10 V. This 38% increase at pH 4 required a total electrical SECEOF of 1.5 MJ/m3 (0.43 kWh/m3). Since the electro-filtration proper requires a minimal SECminEF of only ~23 kJ/m3 (6 Wh/m3), the observed SECEOF is ascribed almost entirely to electrode losses and ionic and molecular transport resistance. (open full item for complete abstract)

Committee: Linda Weavers (Advisor); Hendrick Verweij (Committee Member); John Lenhart (Committee Member); Allison MacKay (Committee Member) Subjects: Environmental Engineering

PhD, University of Cincinnati, 2020, Engineering and Applied Science: Environmental Engineering

Water and Energy are two of the most important and interconnected resources on the planet. Energy is required to treat and transport water. Water is a critical component in most forms of energy generation. Effective management of both are required to sustain human life and protect the environment. Domestic wastewater (DWW) contains both water and energy, but treatment is required to separate them into usable resources. Such treatment requires energy input and to be an energy self-sustaining or “net-zero” process the amount of energy recovered must be equal to what is spent. Anaerobic treatment of DWW biologically converts organic content into methane, which is an energy dense fuel. When operated at psychrophilic temperatures, which is required to realize energy benefits, most of the methane produced remains dissolved in solution. Dissolved methane can be collected using membrane systems, but the recovery efficiency decreases quickly due to increased mass transfer resistance from fouling. Membranes used for solids separation during treatment face the same limitations and fouling control is the largest energy demand in the system. Reducing mass transfer resistance in membrane systems, utilized in the anaerobic treatment of DWW, could allow for the achievement of an energy net-zero, or even net-positive, process. Two methods for reducing mass transfer resistance due to fouling were developed and evaluated in this research. The first method consisted of culturing a methane producing biofilm on the surface of a degassing membrane, which allowed for methane production at the point of collection, negating mass transfer resistance from liquid boundary and fouling layers. This concept was evaluated through the design and operation of Degassed Anaerobic Membrane Bioreactors (DAMBRs). Total methane collection efficiencies of between 89-96% were observed throughout 72 weeks of operation without the need for fouling control or cleaning. Experimental evaluations included: metha (open full item for complete abstract)

Committee: George Sorial Ph.D. (Committee Chair); Jay Garland Ph.D. (Committee Member); Margaret Kupferle Ph.D. (Committee Member); Drew McAvoy Ph.D. (Committee Member); Jonathan Pressman Ph.D. (Committee Member); Makram Suidan Ph.D. (Committee Member) Subjects: Environmental Engineering

Doctor of Philosophy, The Ohio State University, 2021, Aero/Astro Engineering

The detrimental effects of deposition on gas turbine engine performance have become more pronounced as operation in climates with heavy concentrations of airborne particulate has increased over the past several decades. This has introduced relatively new and complex challenges for engine designers and maintenance teams who must account for and try to mitigate the host of negative consequences that can arise when particles accumulate on turbine hardware. The majority of deposition analysis is performed through experimental testing, whether it be in the full-scale engine environment or in a scaled-down facility. The cost involved with designing, manufacturing, and testing hardware can be exorbitant however, and thus computational models that can predict deposition behavior are an attractive and more affordable alternative. Over the past decade, a variety of models have been introduced to address this growing need. The aim of this work is two-fold and is addressed in two parts. The first goal is to improve the current state of deposition modeling by investigating the role that absolute pressure plays in the process. Experiments are first conducted in a High-Pressure Deposition Facility (HPDF) at the Aerospace Research Center (ARC) at the Ohio State University (OSU). Commercially available Arizona Road Dust (ARD) is delivered to an effusion cooling plate at a specified pressure ratio and flow temperature, and the absolute flow pressure is varied over a range of 14.77 atm to study the effect pressure has on the deposition levels and blockage of the effusion cooling holes. Two size distributions (0-3.5 and 0-10 µm) are investigated, and the results indicate that the deposition and blockage rates decrease monotonically as absolute pressure increases. This holds true for both sizes of dust, but the overall blockage rates are much higher for the 0-3.5 µm. The rate of decrease in hole blockage as pressure increases on the other hand is steeper for the 0-10 µm distributi (open full item for complete abstract)

Committee: Jeffrey Bons (Advisor); Randall Mathison (Committee Member); Sandip Mazumder (Committee Member) Subjects: Aerospace Engineering; Mechanical Engineering

Master of Science, The Ohio State University, 2020, Aero/Astro Engineering

This thesis covers the intensive research effort to elucidate the role of elevated temperature in deposition. Several experimental campaigns were conducted in this pursuit. The testing explored high temperature deposition with 0-10 micron Arizona Road Dust (ARD) with the intent of creating a yield strength model that included temperature effects and could be incorporated into the existing OSU deposition model. Experimental work was first conducted in the impulse kiln facility where small amounts of the test dust were placed on ceramic targets and rapidly exposed to temperatures between 1200K and 1500K. Trends in the packing factor confirmed the existence of two threshold values (1350K and 1425K) that could be linked to strength characteristics of the dust when exposed to high temperatures. Using the information obtained from the kiln experiments, HTDF testing was conducted between 1325K and 1525K. Exit temperatures were set at 25K intervals in this region with a constant jet velocity of 150 m/s. The capture efficiency data showed this trend with temperature and indicated a softening temperature and melting temperature of 1362K and 1512K respectively. With these critical values in hand, the Ohio State University Molten Model was created to modify yield strength with particle velocity and temperature. The model was tested using CFD and showed a good capability for capturing particle temperature effects in deposition from an impinging particle-laden jet. A subsequent test campaign was conducted to explore the effect of varying surface temperature on deposition. Hastelloy coupons with Thermal Barrier Coatings (TBCs) were subjected to a constant jet at 1600K jet and 200 m/s while being cooled via a backside impingement jet. Surface temperatures between 1455K and 1125K were impacted with 0-10 micron ARD while an IR camera monitored the surface. Coupons with higher coolant flowrates (lower surface temperature) saw significantly lower deposition rates than the higher surf (open full item for complete abstract)

Committee: Jeffrey Bons Dr. (Advisor); Randall Mathison Dr. (Committee Member) Subjects: Aerospace Engineering

MS, University of Cincinnati, 2019, Engineering and Applied Science: Materials Science

Carbon nanotube (CNT)/polysulfone (PSF) composite membranes capable of being heated were fabricated as an alternative to a CNT/polycarbonate (PC) membrane of a previous study. Membranes were made with pore size in the ultrafiltration range, having pores small enough to remove bacteria and some viruses from water. The membranes were fabricated with non solvent induced phase separation in which dimethylformamide was used as a solvent and water was the non-solvent. N-methyl-pyrrolidone was also tested but was not used to fabricate the final membrane due to the formation of an undesired membrane morphology containing macrovoids. The PSF concentration tested for this application ranged from 15-17 wt%. PSF was cast on a porous sheet of carbon nanotubes consisting of 3 layers. The 15% sample had the best flux of all the samples tested. By selecting a concentration of 15% a pure water flux of 665 LMH was achieved at a pressure of 50 psi. The CNT/PSF membrane is capable of being heated to mitigate biofouling. The semiconducting character of the CNTs allowed for the CNTs to function as a heater by utilizing the process of Joule heating. By applying a potential of 19 V the temperature of the membranes can reach 113±14 °C. This process utilizes 1.82 W of power and can be sustained for more than 10 minutes. The temperature required to effectively kill off E. coli is 100 °C, a temperature achievable with the CNT/PSF membrane [1], [2]. The PSF glass transition temperature was determined to be 184.8±0.8 °C and the CNTs utilized do not oxidize lower than 633 °C, proving the materials will not thermally degrade under regular use. The CNT/PSF membrane was an improved version of the previous CNT/PC membrane. The CNT/PSF membrane had the same heating ability but was more selective, more thermally stable, mechanically stronger, and possessed a protective coating of the CNTs in the composite membrane.

Committee: Vesselin Shanov Ph.D. (Committee Chair); Noe Alvarez Ph.D. (Committee Member); Soryong Chae Ph.D. (Committee Member); Jude Iroh Ph.D. (Committee Member) Subjects: Materials Science

Master of Science, The Ohio State University, 2018, Food, Agricultural and Biological Engineering

Waste streams from food manufacturing operations include significant amounts of water. In many applications, water is used dilute organic or inorganic materials for transportation to a waste treatment facility. The composition and concentration of the waste streams are variable and depend on the type of manufacturing and on the stage of operation within te daily operation. Finally, the composition of these waste streams may represent significant challenges to environmental quality. The overall objective of this project was to reduce the impact of these waste streams using membrane filtration. Two case studies were used to demonstrate the potential applications of membrane filtration. The focus of the first case study was on reducing the composition of a waste streams released to a municipal facility. The second case study involved reclamation of condensate water from whey concentration in an evaporator operation. In the first case study, various levels of membrane filtration were compared to a dissolved air floatation (DAF) treatment. In addition, the various membrane treatments were applied after DAF for an additional level of reclamation. Membranes with six different pore-size were evaluated. The effectiveness of the various treatments was measured by reduction in Chemical Oxygen Demand (COD). DAF treatment provided 75.15 ± 3.95% reduction in COD, and the reduction in COD improved from 85% to 99%, as the membrane pore size decreased. When all membranes were used after a DAF pre-treatment, a reduction in COD to less than 1200 ppm in the permeate stream was achieved. These reductions were independent of the COD in the feed stream. The membrane fouling rates were evaluated for the membranes with the four largest pore-sizes membranes. The membranes with 20 kDa pore-size had the lowest fouling rate during extended fouling-rate studies. In the second case study, the objective was to evaluate the reclamation of condensate from an evaporator used to concentrate whey, (open full item for complete abstract)

Committee: Dennis Heldman (Advisor); Rafael Jimenez-Flores (Committee Member); Sudhir Sastry (Committee Member) Subjects: Environmental Engineering; Food Science

Doctor of Philosophy (Ph.D.), University of Dayton, 2017, Biology

It is now generally recognized that the dominant state of microorganisms in nature is that of the biofilm, a community of microorganisms that grows, not as a free-swimming community, but in close association with an interface between two phases, be it a liquid and solid surface, liquid and air, or even two non-miscible liquids (such as water and oil). This growth form possesses many unique attributes when compared to its planktonic, free-swimming counter part. Biofilms are composed of cells with diverse metabolic states, are protected from their environment by the extracellular matrix, can differ greatly in conditions (e.g. pH, diffusion of nutrients) within the biofilm compared to the bulk medium. These factors result in biofilms being more resistant to biocide and antibiotic treatment than planktonic cells. This resistance has resulted in the pursuit for new ways to both deter the formation of biofilms and eradicate those that have already been established. This current work takes two approaches, in two very different environments, to accomplish these goals. The first chapters address the fouling of aviation fuels by Pseudomonas aeruginosa biofilms and introduces the use of bacteriophage as a method preventing such fouling. The latter portion of this work introduces a cationic porphyrin with the ability to prevent and remediate Pseudomonas aeruginosa and Staphylococcus aureus biofilms in the presence and absence of photoactivation and begins to suggest mechanisms for this activity. This porphyrin has the potential to be applied across a many fields including medicine and industry. Together these approaches begin to address the challenges posed by biofilms.

Committee: Jayne Robinson (Advisor); Mark Nielsen (Committee Member); Karolyn Hansen (Committee Member); Wendy Goodson (Committee Member); Amit Singh (Committee Member) Subjects: Biology; Microbiology

Master of Science, University of Toledo, 2016, Chemical Engineering

Polymers synthesized from renewable plant-based monomers are gaining importance since they reduce reliance on petroleum feedstocks. Cashew nut shell liquid, side-product of cashew nut is an excellent source of naturally derived phenols. Cardanol polymerization is catalyzed by soybean peroxidase has been carried in 2-propanol/phosphate buffer. Reaction proceeds at room temperature, standard pressure and avoids use of toxic organic solvents, such as benzene, a carcinogenic. The enzymatic polymerization route of synthesis is desirable for the environment and contributes to “green polymer chemistry.” In this study, polycardanol is used as a base material for an antifouling coating. This study discusses effects of different additives to study antifouling activities of cardanol-based polymeric coatings to inhibit attachment of Pseudomonas aeruginosa. Polycardanol has been modified with a fluoropolymer and lanthanum strontium ferrite to change surface properties and study its effect on initial attachment of Pseudomonas aeruginosa.

Committee: Dong-Shik Kim (Committee Chair); Youngwoo Seo (Committee Member); Sridhar Viamajala (Committee Member) Subjects: Chemical Engineering

Master of Science, The Ohio State University, 2016, Food Science and Technology

Fouling is a ubiquitous and financially burdensome problem in the food industry, with the potential to affect the safety and quality of products. The impacts of fouling include increased pressure drop, along with reductions in heat transfer and process efficiency. Ultimately, build-up of fouling requires system shutdown for cleaning, leading to reduced product throughput. The overall objective of this research was to investigate the ultra-high temperature (UHT) processing conditions (time and temperature) needed to reduce the rate of fouling and extend run time. Ten kilograms of 20% (w/w) reconstituted nonfat dry milk (NFDM) was processed at 127C, 132C, and 138C, and recirculated for 5 run times ranging from 3min to 60min. Flow rate was constant at 3L/min (NRe,Hold Tube˜3000). Following a water rinse, 0.5% (w/w) sodium hydroxide cleaning solution was recirculated for 30min to remove protein-based fouling from an indirect MicroThermics UHT/HTSTLab-25HV tubular system. Samples of the sodium hydroxide cleaning solution containing fouling were collected and analyzed for protein concentration using Bicinchoninic Acid and Bradford Assays, free hydroxyl group level by active alkali titration and electrical conductivity (EC) meter, and brown color by spectrophotometry at 420nm. These assays were used as indicators of fouling during processing. Results from this research indicated that protein concentration and brown color increased with run time at a given process temperature. In addition, active alkali and EC levels decreased with run time. These measurements became indicators of the rate of fouling at a constant temperature, and the changes were described by a first order model. The first order rate constants at each process temperature (127C, 132C, and 138C) were used to determine activation energy coefficients. First-order rate constants for fouling based on protein concentration were 0.0860min-1, 0.1169min-1, and 0.2053min-1, at 127C, 132C, and 138C, respective (open full item for complete abstract)

Committee: Dennis Heldman (Advisor) Subjects: Engineering; Food Science

MS, University of Cincinnati, 2015, Engineering and Applied Science: Environmental Engineering

Water reuse systems must produce water of consistent quality in order to ensure the protection of human health and the environment. In this study, several online real-time sensors and the CANARY event detection software were utilized to track the treatment performance of a wastewater fed laboratory-scale membrane bioreactor (MBR) under both nominal and simulated failure conditions. The failure/high risk conditions evaluated included a membrane breach, which was mimicked by allowing the reactor mixed liquor suspended solids to bypass the membrane modules, and a high virus load, as could be the case during an outbreak, by spiking MS2 bacteriophage into the reactor. The monitoring system (sensors and CANARY) was evaluated for its ability to differentiate these events from baseline behavior. In all bypass and spiking trials, CANARY issued an alarm that indicated a deviation from the baseline effluent quality in one or more of the sensor signals. Additionally, CANARY issued alarms related to significant operator-induced perturbations to effluent quality throughout the evaluation period. CANARY's performance suggests it can be a useful tool for monitoring the water quality of MBR effluent in water reuse applications. The energy requirements of reuse systems must also be reduced to promote implementation in municipalities and industries. While membrane fouling remains a key hindrance to improving MBR energy efficiency, the incremental process for optimizing operational parameters to mitigate fouling is impractical for full-scale operations. In this study, three physical membrane-cleaning cycles were tested: relaxation, backflushing, and a relaxation/backflushing hybrid, as well as two continuous operational fluxes: one at the instantaneous flux of the physical cleaning cycles, and one at the net flux of the physical cleaning cycles. The affects of these operational modes on fouling were compared to determine whether or not any operation showed significant operational su (open full item for complete abstract)

Committee: George Sorial Ph.D. (Committee Chair); William E. Platten III Ph.D. (Committee Member); Pablo Campo Ph.D. (Committee Member) Subjects: Environmental Engineering

Doctor of Philosophy, University of Akron, 2014, Polymer Science

Polyisobutylene (PIB) has a unique combination of properties including chemical/oxidative resistance, low Tg (~70 °C) and hydrophobicity.1 PIB-based materials have also been found to have excellent biocompatibility and biostability: a PIB-based triblock copolymer thermoplastic elastomer (TPE) [poly(styrene-b-isobutylene-b-styrene)] (SIBS) is FDA-approved as a drug eluting coating for coronary stents.2 A new generation of PIB-based TPEs, with an arborescent or tree-like core (arbPIB) and plastic phases composed of blocks of polystyrene or poly(p-methyl styrene) (MS) has been developed in Professor Puskas group. These materials display unique TPE properties to make them very attractive for biomedical applications.3 The biocompatibility of these novel block copolymers has already been demonstrated in vitro and in vivo in rabbits.4 The Puskas group proposed to modify the surface properties of PIB-based TPEs using a modular approach. Using this approach it is possible to modify the surface chemistry and topology independently. The surface chemistry can be modified by “gluing” low molecular weight functionalized PIBs (PIB-X) to the surface of the TPEs. This “modular” approach will give unprecedented control over surface chemistry and topology and will contribute to new fundamental understanding of the effects of surface properties on the biocompatibility of polymeric materials. In this work PIB with a primary hydroxy head group (HO-PIB) was made in situ by living carbocationic polymerization using propylene oxide as initiator and titanium tetrachloride (TiCl4) as coinitiator. PIB functionalized with non-fouling moieties (PIB-X) was then synthesized from HO-PIB using Candida antarctica Lipase B (CALB) as enzymatic catalyst and spin coated onto the surface of the TPE. Protein adsorption studies using Surface Plasmon Resonance (SPR) demonstrated decreased fibrinogen (Fg) adsorption to the modified surface. XPS analyses provided clear evidence of the effectiveness of the mo (open full item for complete abstract)

Committee: Judit E. Puskas Dr. (Advisor); William Landis Dr. (Committee Chair); Gary R. Hamed Dr. (Committee Member); Chrys Wesdemiotis Dr. (Committee Member); Nic D. Leipzig Dr. (Committee Member) Subjects: Biomedical Research; Materials Science; Polymer Chemistry

Doctor of Philosophy, The Ohio State University, 2013, Aero/Astro Engineering

Experimental and computational studies were conducted regarding particle deposition in the internal film cooling cavities of nozzle guide vanes. An experimental facility was fabricated to simulate particle deposition on an impingement liner and upstream surface of a nozzle guide vane wall. The facility supplied particle-laden flow at temperatures up to 1000°F (540°C) to a simplified impingement cooling test section. The heated flow passed through a perforated impingement plate and impacted on a heated flat wall. The particle-laden impingement jets resulted in the buildup of deposit cones associated with individual impingement jets. The deposit growth rate increased with increasing temperature and decreasing impinging velocities. For some low flow rates or high flow temperatures, the deposit cones heights spanned the entire gap between the impingement plate and wall, and grew through the impingement holes. For high flow rates, deposit structures were removed by shear forces from the flow. At low temperatures, deposit formed not only as individual cones, but as ridges located at the mid-planes between impinging jets. A computational model was developed to predict the deposit buildup seen in the experiments. The test section geometry and fluid flow from the experiment were replicated computationally and an Eulerian-Lagrangian particle tracking technique was employed. Several particle sticking models were employed and tested for adequacy. Sticking models that accurately predicted locations and rates in external deposition experiments failed to predict certain structures or rates seen in internal applications. A geometry adaptation technique was employed and the effect on deposition prediction was discussed. A new computational sticking model was developed that predicts deposition rates based on the local wall shear. The growth patterns were compared to experiments under different operating conditions. Of all the sticking models employed, the model based on wall shear, (open full item for complete abstract)

Committee: Jeffrey Bons (Advisor); Ali Ameri (Committee Member); Michael Dunn (Committee Member); Datta Gaitonde (Committee Member); Sandip Mazumder (Committee Member) Subjects: Aerospace Engineering

Master of Science, The Ohio State University, 2013, Aero/Astro Engineering

A high temperature combustion rig was used to impact bituminous and lignite coal fly ash particles on an impingement plate at conditions similar to those found in the hot section of a gas turbine engine. Individual particles were tracked using particle shadow velocimetry as they either rebounded from or deposited on the plate surface. The effects of particle size, particle impact velocity, impact angle, particle temperature, and plate temperature were explored. Particle diameter ranged from 30-800µm, impact velocity ranged from 5-160 m/s, impact angle ranged from close to 0° to 90°, and temperatures ranged from ambient conditions to 2100°F. Increasing diameter, impact velocity, and plate temperature were all shown to decrease the total coefficient of restitution. The angular coefficient of restitution was shown to decrease with increased impact angle for bituminous ash. The total coefficient of restitution versus both impact angle and particle temperature yielded unexpected trends. For bituminous ash, a peak in coefficient of restitution occurred for all temperature cases at an impingement angle of 40°. Both higher and lower impact angles resulted in a decrease in coefficient of restitution. A peak in coefficient of restitution occurs between 1250-1500°F for both the bituminous and lignite ash, decreasing at both higher and lower temperatures. Possible explanations for these unexpected results are discussed.

Committee: Jeffrey Bons Ph.D (Advisor); Jen-Ping Chen Ph.D (Committee Member) Subjects: Aerospace Engineering

PhD, University of Cincinnati, 2009, Engineering : Environmental Engineering

The Membrane Bioreactor (MBR) process has been widely applied in the water/wastewater treatment field, and is regarded as an important next-generation technology for wastewater treatment plants. Extensive research and industrial practices have been going on for process optimization and cost reduction. In this study, an innovative thick membrane with large pore sizes was used to develop a new gravity flow MBR process. Two MBR reactors with 0.25cm and 0.48cm thick membrane sheets were operated in parallel to a Conventional Activated Sludge (CAS) reactor. Operation conditions were identical for both processes during the treatment of a synthetic wastewater. The objectives of this study include: 1) Test the long term wastewater treatment performance of this new MBR process and the impact of sludge ages; 2) Study the membrane fouling/plugging propensity during the operation, fouling development mechanism and potential control measures; 3) Evaluate the possible application of this innovative MBR process on the removal of emerging contaminants such as pharmaceutical/pesticide chemicals at low concentration level. Research results demonstrated that: 1) Consistent permeate water quality was achieved throughout the one year periods under SRT of 6 days and 15 days respectively; 2)The bigger membrane pore size allows this novel MBR system to be operated with less energy and low maintenance requirements, as well as obtaining better effluent quality than CAS system; 3). This MBR system demonstrated reliable long-term anti-fouling ability. Mixed liquor concentration was the major contributing factor for membrane fouling of this MBR system. Dynamic biofilm that formed inside the membrane pores and sludge cake layer on membrane surface improved permeate water quality and strengthened fouling resistance. 4) Removal of selected emerging contaminant chemicals was compound-specific and there was no significant difference between MBR and CAS on percentage of removals. Findings from thi (open full item for complete abstract)

Committee: Makram Suidan PhD (Committee Chair); Albert D. Venosa PhD (Committee Member); George A. Sorial PhD (Committee Member); Paul L. Bishop PhD (Committee Member) Subjects: Environmental Engineering