Master of Science in Engineering, University of Akron, 2014, Civil Engineering

The objective of this study was to investigate the formation of iodinated disinfection by-products (iodo-DBPs) where iodinated x-ray contrast media (ICM), Iopamidol, acted as source of iodine, with respect to pH (6.5, 7.5, 8.5 and 9.0) in the presence of natural organic matter (NOM) and chlorinated oxidant. This was achieved by varying the NOM concentration as well as iopamidol concentrations. Iodinated trihalomethane (iodo-THM) formation was highest at pH 9.0 for chlorine and at pH 6.5 for monochloramine. A considerable increase in formation was observed from pH 6.5 to 7.5 and from 8.5 to 9.0 with respect to chlorine as oxidant. Monochloramine expressed a decreasing trend from pH 6.5 to 9.0. The most predominately formed iodo-THM was dichloroiodomethane, 57.5 nM for chlorine at pH 9.0 (DOC = 2.51 mg/L-L) and 35.2 nM for monochloramine at pH 6.5 (DOC = 2.51 mg/L-L). Chloroform formation was also impacted by the introduction of iopamidol to reactor. Monochloramine produced a wider variety of iodo-DBPs at lower concentrations in comparison to chlorine. Variation of NOM proved to impact the formation of iodo-DBPs. When NOM levels were reduced to a quarter of the original capacity (2.51 – 0.63 mg/L-L) dichloroiodomethane formation doubled at pH 9.0 with respect to chlorine (110.5 nM). Monochloramine expressed a decreasing trend with respect to decreasing levels of NOM with the source water. For both oxidants, half and quarter capacity of NOM, 1.26 and 0.63 mg/L-L respectively, expressed considerably similar formation. Additionally, two-way analysis of variance (two way-ANOVA) tables were generated for two response variables, chloroform and dichloroiodomethane. With respect to each oxidant, iopamidol and pH were evaluated while NOM level remained constant and NOM and pH were evaluated while iopamidol remained constant. In regard to chloroform as the response variable with varied DOC, significance was yielded for both DOC (p-value of 0.0004) and pH (p-val (open full item for complete abstract)

Committee: Stephen Duirk Dr. (Advisor); Teresa Cutright Dr. (Committee Member); Lan Zhang Dr. (Committee Member) Subjects: Civil Engineering; Environmental Engineering

PhD, University of Cincinnati, 2008, Engineering : Environmental Engineering

The efficacy of chlorine dioxide as a disinfectant, in case of bioterrorism attack, in water networks was evaluated using Bacillus globigii as a surrogate to Bacillus anthracis, the main cause of anthrax. The efficacy of chlorine, the traditional disinfectant, was tested earlier and was shown to be deficient as a disinfectant in such a scenario. In a previous study, free available chlorine (FAC) concentrations were assessed to concentrations up to 75 mg/L and it was reported that the residual spore attachment after disinfection was 3.8x103 CFU/cm2. In this work, experiments in similar conditions to those carried out earlier by Szabo (2006) were conducted using chlorine dioxide as a disinfectant. The sectioning of biofilm depth into layers parallel to the substratum was also performed, prior to and during disinfection at concentrations of 15 and 25 mg/L chlorine dioxide, to study the attached spore stratification and change in viable spore fraction in each layer during disinfection. Preceding this, experiments were performed to assess the hypothesis of chlorine dioxide being a better disinfectant than chlorine and to establish a basis of comparison between chlorine and chlorine dioxide concentrations and attributes. Aqueous chlorine dioxide films on glass, plastic and aluminum, with and without surfactant, showed that the rate at which chlorine dioxide leaves the liquid phase to the gaseous phase was found to correlate with the film thickness. Chlorine dioxide was able to partition with and break through the caprylic acid layer at a very fast rate. These results supported the hypothesis that chlorine dioxide will not be hindered by extracellular polymeric substances (EPS) when disinfecting a biofilm layer. The bulk chlorine and chlorine dioxide experiments were performed with 1.0, 1.5 and 2.0 mg/L of both disinfectants in duplicates. Chlorine dioxide was able to achieve up to three log reductions of B. globigii in about two hours while chlorine reached 3 log reductio (open full item for complete abstract)

Committee: Paul Bishop (Committee Chair); George Sorial (Committee Member); Margaret Kupferle (Committee Member); Alison Weiss (Committee Member) Subjects: Environmental Engineering

Master of Science, The Ohio State University, 2006, Graduate School

Committee: Not Provided (Other) Subjects:

Doctor of Philosophy, The Ohio State University, 2024, Civil Engineering

The global health risks presented by waterborne pathogens are of significant concern. Waterborne pathogens can survive treatment processes and show resistance to disinfectants, which potentially resulting in disease that greatly threatens human health. Despite efforts put into eliminating waterborne pathogens, they are still detected in engineered aquatic environments such as wastewater treatment plants (WWTP) and drinking water distribution systems (DWDS), which are potential sites of human exposure. Antibiotic resistant bacteria (ARB), with their transmissible antibiotic resistant genes (ARG), and opportunistic pathogens (OP), with their virulence factors and persistence in biofilms to resist disinfectants, have captured a lot attention. The seriousness of bacterial diseases transmitted through water prompts the investigation of how engineered disinfection technologies impact water microbiomes to limit dissemination of OP and prevent ARB infections. Ultraviolet (UV) irradiation is an advantageous disinfection technology that causes DNA or protein damage with little to no production of toxic by-products. However, investigations regarding the interactions between ARB and OP with different UV wavelengths, and the differences of UV disinfection on lab-scale strains compared to field or clinical samples and how UV impacts microbial communities are still needed. The research addresses these gaps through three objectives. (1) Investigate the impact of UV wavelengths on ARB at cell and molecular levels and explore the underlying mechanisms of different wavelengths using a lab strain ARB. A complementary study was done to further explore the existence of ARB collected from field WWTP influents and investigate impact of UV disinfection on ARB in this environment. (2) Explore UV disinfection of OP using typical lab strains and clinical isolates of nontuberculous mycobacteria (NTM) at cell and molecular levels, focusing on UV resistance differences related to pathogenicity (open full item for complete abstract)

Committee: Natalie Hull (Committee Chair); Vanessa Hale (Committee Member); Jiyoung Lee (Committee Member); Karen Danneniller (Advisor) Subjects: Environmental Engineering; Microbiology; Molecular Biology

Doctor of Philosophy, The Ohio State University, 2024, Civil Engineering

Microbial water quality in drinking water distribution systems (DWDS) must be managed appropriately to protect public health. Ultraviolet (UV) disinfection effectively inactivates a wide range of microorganisms while generating minimal to no disinfection byproducts (DBPs), but does not provide a disinfection residual for protecting water quality from treatment to tap. Regulated drinking water quality is an important standard for health reasons, but end user perceptions of drinking water are a commonly overlooked issue of drinking water treatment and distribution. This dissertation explores the interrelatedness of end users and drinking water quality and investigates UV-based solutions to manage drinking water and prevent bacterial contamination in centralized and distributed applications. In Chapter 2, a coupled human-natural systems approach was used to determine the connections among drinking water quality, end user perception, and causal factors in drinking water systems. Interviews and water sampling from twenty-four households in a chlorinated DWDS in rural Ohio were conducted. An aggregated index of drinking water perceptions (safety, satisfaction, overall quality) was correlated with experiences of household water issues, but not necessarily explained by measured tap water quality. Water quality varied spatially throughout the DWDS. Analysis of community level cognitive maps revealed that customers perceived environmental quality, pollution, infrastructure quality, and water system service performance as other indicators of tap water quality. In Chapter 3, hydropowered UV disinfection technology for point-of-use applications was prototyped and evaluated by bench-scale flow through testing for disinfection performance. Hydropowered UV disinfection may offer a decentralized solution for maintaining microbial water quality in DWDS (e.g., booster disinfection). Currently, the technology is feasible at scales of point-of-entry and above, but economic analyse (open full item for complete abstract)

Committee: Natalie Hull (Committee Chair); Matthew Hamilton (Committee Member); Clarissa Belloni (Committee Member); Karen Dannemiller (Committee Member); Linda Weavers (Committee Member) Subjects: Civil Engineering; Environmental Engineering

Master of Science, The Ohio State University, 2023, Aerospace Engineering

Over the last decades, research has shown that water applications serving small scales (small population) is causing major health problems due to water pollution. Those applications include home and hospital water supply line. In fact, water pollution is increasing year after the other due to the bad use of the resources available. However, in the United States, engineers are trying to benefit now from the renewable energy available, including hydropower, wind, and solar power. Small-scale hydropower has been the focus of engineers over the last years since generating power at that small-scales can be a solution for developing and rural areas all over the world where money access is not available. Turbine designs available in the market are typically larger and provide more power than the power required for small scales applications (about 200W needed). As a result, this paper seeks to solve the water pollution at small-scales applications by designing a pico-hydropower system that is able to provide enough power to run the water disinfection reactor. Water disinfection is done using UV LED lights that are healthier for humans and for the environment. This new emerging technology is still under review and will be more efficient by the upcoming years. The hydropower system designed is based on a new concept of using a centrifugal pump and reverse the flow path to generate energy instead of consuming energy. Two new methods were created to be able to predict the multistage pump performance when removing and adding stages along with predicting the turbine performance at different stages. The results show that the PAT technology is efficient in terms of generating energy that is enough to water disinfection at small scales application.

Committee: Clarissa Belloni (Advisor); Natalie Hull (Committee Member); Randal Mathison (Committee Member) Subjects: Aerospace Engineering; Mechanical Engineering

Doctor of Philosophy in Engineering, Cleveland State University, 2021, Washkewicz College of Engineering

In this study, we developed a comprehensive mathematical model to predict the free chlorine (FC) concentration and bacterial cross-contamination during produce wash processes. A second-order chemical reaction model for FC decay which utilizes a proportion of chemical oxygen demand (COD) as an indicator of organic content in the wash water was employed, yielding an apparent reaction rate of 9.45 ± 0.22 × 10-4 µM-1.min-1. Using a proportion of successive changes in COD in the wash water due to produce washing, typically ranging from 6 to 11% across produce types, the model was able to consistently predict experimental FC levels, however, we note that while the FC level drops, the COD level stays constant. Therefore, we established the total amino acids concentration as an alternative indicator of organic load, and modified our model based on modeling the reaction kinetics of chlorine and amino acids. Apparent reaction rate between FC and amino acids was in the range of 15.3 – 16.6 M-1.s-1 and an amplification factor in the range of 11.52 - 11.94. This study also presents a modified disinfection kinetics model to evaluate the potential effect of organic content on the chlorine inactivation coefficient of Escherichia coli O157:H7 in produce wash process. While the chlorine inactivation coefficient of E. coli was 70.39 ± 3.19 L.mg-1.min-1 in the absence of organic content, it dropped by 73% for a COD level of 600 - 800 mg.L-1. Finally, the mechanisms by which FC inactivates E. coli was studied. Results showed that at low levels of FC and shorter exposure times, cell surface became rough and plicate; however, holes and wrinkles formed on the cell surface at higher FC concentrations or at longer exposure times, causing significant damage to the cell membrane. The cellular permeability changed due to chlorination, resulting in a significant decrease in the number of viable cells. Besides, around 3.45% ± 0.62 of cells lost their culturability and transform to viable but (open full item for complete abstract)

Committee: Chandrasekhar Kothapalli (Committee Chair); Jorge Gatica (Committee Member); Joanne Belovich (Committee Member); Daniel Munther (Committee Member); Srinivasan Parthasarathy (Committee Member) Subjects: Chemical Engineering; Microbiology

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

Dissolved organic matter (DOM) is ubiquitous in natural and engineered aquatic systems. DOM can be problematic during drinking water treatment due to its ability to scavenge oxidants and react with chlorine to form carcinogenic disinfection byproducts (DBPs). Drinking water treatment plant operators aim to minimize DBP formation by removing DOM (alum coagulation and activated carbon sorption) or altering DOM composition (permanganate oxidation). While permanganate pre-oxidation has been claimed widely to be an effective strategy to reduce DBP formation, its impact on drinking water treatment and subsequent DBP formation remains poorly understood. Here, a novel ultrahigh resolution mass spectrometric approach was used to characterize DOM by combining data from multiple ionization techniques to provide greater insight on DOM molecular level changes induced by treatment. In Chapter 2, this approach was applied along with Fourier Transform-infrared spectroscopy and ultraviolet-visible spectroscopy to understand which DOM components react with permanganate for two DOM isolates (a terrestrial isolate and a microbial isolate). Aromatic and nitrogenous components were found to react with permanganate and help explain previously observed trends between permanganate-DOM reaction rates and SUVA-254 values as well as why algal-derived DOM can efficiently scavenge permanganate. In Chapter 3, the impact of permanganate pre-oxidation on the response of DOM to subsequent treatments was investigated using ultrahigh resolution mass spectrometry and bulk characterization techniques for three DOM isolates that represented different DOM source types: terrestrial, algal-impacted, and wastewater effluent-impacted. Permanganate pre-oxidation enhanced removal of aromatic components by coagulation and activated carbon sorption because it added negatively charged functional groups that interacted more favorably with sorption sites. It was also observed that complimentary treatments (i.e., coa (open full item for complete abstract)

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

Master of Science, The Ohio State University, 2020, Civil Engineering

Ultraviolet (UV) disinfection provides chemical free inactivation of a wide range of microorganisms. One primary mechanism of UV inactivation of bacteria is through DNA damage, which inhibits bacterial replication and reproduction. The ability of bacteria to repair DNA damage raises concerns about the post-treatment safety of UV treated water, especially if bacteria repair and regrow under favorable conditions. A well-known repair process is photorepair, which can lead to photoreactivation of inactivated cells. To address this concern, UV disinfection processes can be optimized by selecting specific wavelengths and UV doses to prevent repair and regrowth in various water treatment contexts. Emerging UV technology, such as UV LED devices, can be tailored to emit specific wavelengths to prevent microbial repair. In this study, UV-LEDs with nominal wavelengths 265, 280, and 285 nm and combined 265 + 285 nm were applied in collimated beam tests to quantify inactivation and photoreactivation kinetics of E. coli. At UV doses above 25 mJ/cm2, which were not evaluated in previous UV disinfection studies, the inactivation efficacy was highest for 265 + 285 nm, followed by 265 nm, 285 nm, and 280 nm. Both time-based and photorepair fluence-based photoreactivation were quantified. After 40 mJ/cm2, photoreactivation was greater for 265 + 285 nm than 265 nm. This was unexpected because the contribution of 285 nm in the combined wavelength disinfection was expected to suppress repair due to protein damage. Inactivation kinetics and regrowth kinetics may impact accurate quantification of photoreactivation. Molecular detection methods are needed to measure DNA damage repair to distinguish regrowth from repair. Photorepair is a concern after UV disinfection for point of use and decentralized community water treatment. A quantitative microbial risk assessment (QMRA) algorithm was developed to estimate probability of infection associated with pathogenic E. coli in community drin (open full item for complete abstract)

Committee: Natalie Hull PhD (Advisor); Allison MacKay PhD (Committee Member); Karen Dannemiller PhD (Committee Member) Subjects: Civil Engineering; Environmental Engineering; Microbiology

Doctor of Philosophy, University of Toledo, 2020, Engineering

The increasing occurrence and severity of cyanobacterial harmful algal blooms (HABs) in freshwater have continuously challenged the safe drinking water supply. During HAB, public attention mainly focuses on the cyanotoxins, which associated with health issues, while HAB also generated massive amounts of algal cells, increasing the loading of algal organic matter (AOM) in the drinking water treatment plants (DWTPs). AOM is an algae-derived autochthonous natural organic matter (NOM), which contains high fraction of hydrophilic and nitrogenous compounds. Conventional treatment processes, comprised of coagulation, sedimentation, and granular media filtration, are known to be ineffective in completely removing NOM, including AOM [1, 2]. Although ozone has been widely adopted by water utilities to break down complex organic compounds and reduce DBP formation, ozonation practices can adversely increase concentrations of assimilable organic carbon (AOC), which in turn can be rapidly utilized and support biofilm growth in downstream filters and drinking water distribution systems [3, 4]. Currently, remain largely unknown for the growth of biofilms under the impacts of dfferent NOM, including AOM in the filters and drinking water distribution systems (DWDSs). Therefore, the main research goal of this study is to investigate the impacts of orgniac matter on microbial biofilms in engineered drinking water systems (EDWSs). Specifically, the first objective of this study aimed to examine how the assembly processes and their associated factors (e.g., influent characteristics, biological interactions) drive the temporal dynamics of bacterial communities in full-scale BAC filters, which underwent ozone implementation to better handle the adverse effects of HABs. The obtained results revealed that along with the increase of bacterial taxonomic richness and evenness, stochastic processes became more crucial to determine the bacterial community assembly in the summer and autumn aft (open full item for complete abstract)

Committee: Youngwoo Seo (Committee Chair); Cyndee L. Gruden (Committee Member); Dae-wook Kang (Committee Member); Hodon Ryu (Committee Member); Sridhar Viamajala (Committee Member) Subjects: Environmental Engineering; Microbiology

Doctor of Philosophy, University of Akron, 2017, Engineering

Iopamidol, one of the most commonly used and detected iodinated X-ray contrast media in water sources, is inert in the human body but reacts and degrades in the presence of aqueous chlorine to form highly cytotoxic/genotoxic disinfection by-products (DBPs). The objectives of this study were to investigate (1) the effect of iopamidol on the formation and speciation of DBPs in multiple source waters (SWs), (2) the formation of TOX/DBPs in SWs containing iopamidol, bromide, and chlorinated oxidants, (3) the impact of prechlorination time on TOX/DBP formation during chloramination of SWs containing iopamidol and (4) kinetic modeling of TOX, iodate, and DBP formation due to chlorination of iopamidol. SWs from Akron, Barberton, and Cleveland Water Treatment Plants containing iopamidol or iopamidol/bromide were dosed with chlorinated oxidant at pH 6.5-9.0 for 0-72 h. The study showed that the yields of either TTHMs or HAAs exhibited a strong correlation with humic, fulvic, and combined fulvic and humic fractions at pH 7.5. Similarly, the yields of TOCl/UTOCl exhibited strong correlation with SUVA254 at pH 7.5. Although iopamidol directly formed CHCl3, TCAA, and CHCl2I in chlorinated water; iopamidol exhibited minimal impact on DBP formation compared to NOM. In the presence of bromide and aqueous chlorine, iopamidol formed more DBPs. TOI loss was unaffected by the concentrations of bromide. TOCl and TOBr, respectively decreased and increased with increasing bromide concentration but was unaffected by iopamidol concentration. As bromide concentration increased the concentrations of fully brominated DBPs increased while fully chlorinated DBPs and CHCl2I decreased. CHBrClI increased with increasing bromide concentration in CSW. Also, iodo-DBPs increased with increasing iopamidol concentration. Generally, in the presence of bromide and iopamidol, lower amounts of DBPs including iodo-DBPs were formed in chloraminated SWs then chlorinated SWs. In SWs chlorinated before (open full item for complete abstract)

Committee: Stephen Duirk (Committee Chair); Christopher Miller (Committee Member); Teresa Cutright (Committee Member); Chelsea Monty (Committee Member); John Senko (Committee Member) Subjects: Chemistry; Civil Engineering; Environmental Engineering; Water Resource Management

Doctor of Philosophy, The Ohio State University, 1953, Graduate School

Committee: Not Provided (Other) Subjects: Agriculture

Master of Environmental Science, Miami University, 2016, Environmental Sciences

For this internship report, I chose a four-month co-op at the Metropolitan Sewer District of Greater Cincinnati (MSDGC). In a bench-scale study, I compared the disinfection efficiency of peracetic acid (PAA) with the Mill Creek Treatment Plant's (MCTP) current disinfectant, sodium hypochlorite (NaOCl). In recent years, disinfection with PAA has gained attention as a chlorine alternative because of the absence of toxic or mutagenic disinfection by-products. The results obtained indicate that PAA and NaOCl have similar disinfection efficiency against the target organisms of Fecal Coliform and Escherichia coli (E. coli). Four parts per million (ppm) with a 10 minute contact time was necessary for both disinfectants to reach permit level inactivation for Fecal Coliform and 5 ppm to inactivate E. coli. It is recommended that doses 2-5 ppm be pilot-scale tested at MSDGC's Little Miami Treatment Plant (LMTP) in order to determine the dose and contact time necessary to reach permit level inactivation. It is estimated that a dose of 4 ppm PAA will result in a chemical cost savings of 95% for LMTP. This report describes peracetic acid, relevant laws and regulations, study results and discussion, and future projects.

Committee: Jason Rech (Advisor); Sarah Dumyahn (Committee Member); Vincent Hand (Committee Member) Subjects: Environmental Science

PhD, University of Cincinnati, 2016, Engineering and Applied Science: Environmental Engineering

Chlorination has significantly reduced the spread of waterborne disease worldwide, and as a result, eliminated a major source of human mortality in developed and developing countries since it began over a century ago. Unfortunately, the definitive health benefits of chlorination are not without cost: the formation of toxic disinfection by-products. In an effort to increase disinfection efficiency and limit downstream by product formation, advanced oxidation processes have been explored and expanded. Despite the demonstrated efficacy of oxidative disinfection, residual oxidant and reactant stability in treated water remains a concern. An ideal oxidant would act on a wide range of target organisms, potentially with a targeting capability, produce little to no harmful by-products, possibly through generation of reactive oxygen, and be harmless when consumed by the end user. This research seeks to develop a selective, photocatalytic , biological disinfection system based on the fusion protein StrepMiniSOG (SMS) we recently developed and will pursue two main goals: 1) characterization of a new biological disinfection system, including RO species, production rates, and quantum efficiency, and 2) disinfection studies of several microbial targets to determine the disinfection kinetics and the ability of the system to target specific microorganisms within a mixed population. The proteinaceous SMS photodisinfection system proposed in this work will reduce the negative impacts of traditional disinfection methods while the demonstration of selective removal will allow for its application to a broad range of disinfection situations.

Committee: David Wendell Ph.D. (Committee Chair); Mallikarjuna Nadagouda Ph.D. (Committee Member); Dionysios Dionysiou Ph.D. (Committee Member); George Sorial Ph.D. (Committee Member) Subjects: Environmental Engineering

Master of Science (MS), University of Toledo, 2015, Pharmaceutical Sciences (Pharmacology/Toxicology)

The process of water chlorination results in production of different disinfection byproducts (DBPs), including dichloroacetate (DCA) and trichloroacetate (TCA). The compounds have been found to be hepatotoxic and hepatocarcinogenic in rodents. Previous studies have indicated the roles of oxidative stress (OS) and phagocytic activations in the induction of these effects in B6C3F1 mice. Also, previous studies have reported effects of DCA and TCA mixtures that ranged from additive to greater than additive on the induction of hepatic OS and additive to less than additive on the induction of phagocytic activation in mice. In this study, frozen peritoneal lavage cells collected from mice treated for those previous studies were used. In those studies, groups of mice were administered 7.5, 15, 30 mg/kg/day of DCA, 12.5, 25, 50 mg/kg/day of TCA, and 3 different mixtures of the compounds (Mix I, Mix II and Mix III) post orally for 13 weeks. The DCA: TCA ratios in Mix I, Mix II, Mix III corresponded to 7.5:12.5, 15:25, 30:50 mg/kg/day, respectively. Mice were then sacrificed and the peritoneal lavage cells (PLCs) were isolated and kept frozen at -80 C. Cells were assayed for the activities of the antioxidant enzymes, superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GSH-Px), as well as for the amount of glutathione (GSH). DCA, TCA and mixtures administration resulted in dose-dependent increases in SOD activity. Also, DCA, TCA, and mixture I treatments resulted in no change in CAT or GSH-Px activities while Mix II and Mix III resulted in significant increases in those enzyme activities. While 50 mg/kg/day TCA, and Mix I and Mix. II resulted in significant increases in total GSH levels; the rest of the other treatments did not result in significant changes in the levels of that biomarker. Failure of phagocytic activation has been previously suggested to contribute to increases in the hepatotoxic/ hepatocarcinogenic effects of DCA and TCA, and mixtur (open full item for complete abstract)

Committee: Ezdihar Hassoun (Committee Chair); Ming-Cheh Liu (Committee Member); Zahoor Shah (Committee Member) Subjects: Pharmacology; Pharmacy Sciences; Toxicology

MS, University of Cincinnati, 2014, Engineering and Applied Science: Materials Science

Catheter-related bloodstream infections (CRBSI) are one of the major problems faced by patients with renal disease who undergo long-term catheterization for hemodialysis [1]. Polycarbonate and polyether urethanes are most commonly used as long term indwelling catheters in these clinical applications [2].The two routes of CRBSI, namely surgical site infection and contamination of catheter hub are currently prevalent and addressed by cleaning with an antiseptic solution, according to the CDC Guidelines for Prevention of Intravascular Catheter-related infections, 2011 [3].Catheter cleaning methods have evolved over the years with the latest being the use of a disinfectant impregnated sponge to clean the hub prior to initiating hemodialysis [4]. However, this technique does not cater to the proximal caps as well as distal region of the catheter that also needs to be maintained in a sterile condition. Regardless of the methods of sterilization, catheter sites, and time of exposure, the biostability of catheter materials is critical in terms of maintaining the primary role of catheters. In this study, we hypothesize a technique that will expose the catheter hub and distal region to the disinfectant solution for a long time. Owing to the demands for hemodialysis, the polyurethanes used to make the catheter extension need to maintain stability in terms of their mechanical properties and ensure reliable and safe function. The mechanical, thermal and molecular stability of two medical grade polyurethanes commonly used in making catheter extensions for hemodialysis catheters, was investigated. Test conditions involved long term exposure (up to 12 weeks at 37oC and 50% RH) to CHG, a commercially available disinfectant solution (Dyna-Hex 4% aqueous Chlorhexidine Gluconate solution). Post exposure, for Polycarbonate urethane, mechanical tests showed reduction in average strength (from 55.29±0.6 MPa to 48.5±3.98 MPa), average toughness (from 83.27±10.9 J/m3 to 69.9±13.82 J/m3), av (open full item for complete abstract)

Committee: Balakrishna Haridas PH.D. (Committee Chair); Jude Iroh Ph.D. (Committee Member); Marepalli Rao Ph.D. (Committee Member); Donglu Shi Ph.D. (Committee Member) Subjects: Materials Science

Master of Science, University of Toledo, 2014, Chemical Engineering

Disinfection by-products (DBP) formation in drinking water systems is a persistent issue for water utilities. Although DBP formation is complex due to the multitude of chemical and biological interactions that occur, unremoved natural organic matter (NOM) entering the water distribution system is generally regarded as the primary precursor for DBP formation. In addition, NOM also provides nutrients that support microbial growth and persistent biofilm formation. Biofilm formation is widespread within the water distribution system due to the continuous influx of unremoved NOM. Biofilm and its associated extracellular polymeric substances (EPS) provide a dynamic repository for organic matter accumulation, and can act as a DBP precursor. Trihalomethanes (THMs) and Haloacetic acids (HAAs) represent the major classes of regulated DBPs, yet there are several others that form due to the complex interaction between the organic matter and the disinfectants. The unknown total organic halogens (UTOX) is believed to contain toxicologically vital compounds. Until recently, there have been no reliable studies analyzing the relative contributions of biofilm and its associated DBP precursors to DBP formation and speciation, and how these different precursors contribute to the total organic halogen (TOX) formation. This work seeks to abridge this knowledge gap by analyzing the DBP formation from chlorination of biofilms in simulated water distribution systems. The results of this study provide critical information about potential contributions of biofilms to the formation of DBPs and UTOX in the distribution systems and can help water utilities better control the levels of both regulated and unregulated DBPs while at the same time reducing health risks associated with DBPs. To help elucidate this interaction, heterotrophic plate counting (HPC) of bacterial colonies in different pipe materials under different chlorine residuals were conducted. Additionally, DBP and TOX formation tests (open full item for complete abstract)

Committee: Youngwoo Seo Dr. (Advisor); Dong-Shik Kim Dr. (Committee Member); Guanghui Hua Dr. (Committee Member) Subjects: Chemical Engineering; Environmental Engineering

MS, University of Cincinnati, 2001, Engineering : Environmental Engineering

The effect of the distribution system on water quality seems complex. Water demands and average residence times change continually, and chlorine residuals depend on these changing residence times as well as changes in temperature, pH, and organic matter characteristics caused by distribution system hydraulic dynamics. Furthermore, these changing physical/chemical conditions inherently affect the formation of regulated disinfection by-products (DBPs). The research focuses on a water distribution system in eastern Kentucky, which is fed by a 5 MGD conventional treatment plant. The field study was conducted in two phases. A 24-hour hydraulic field sampling event was performed to provide basic data for characterizing the system hydraulics and for understanding the kinetics of chlorine decay and DBP formation. A 48-hour water quality sampling event was conducted using the utility's four regulatory sampling locations, augmented by 15 locations designed to sample representative water from storage tanks, dead-ends, and different pipe materials and ages.

Committee: Dr. James Uber (Advisor) Subjects: Engineering, Environmental

MS, University of Cincinnati, 2012, Engineering and Applied Science: Environmental Engineering

Disinfection by-product formation within drinking water distribution systems is an inevitable circumstance due to reactions between residual chlorine and organic matter. While regulated compounds must be below the maximum contaminant levels, utilities face many challenges such as more stringent regulations, excess capacity within distribution systems, and changes in consumer demands (e.g., conservation efforts) that can compromise a utility's ability to meet water quality regulations. One technology that can be an effective part of a THM management strategy is aeration. Thus, the overall objective of the research was to evaluate fine bubble aeration as an in-system THM mitigation strategy to satisfy distribution system regulatory concentrations. The first part of the study performed controlled experiments using a laboratory-scale reactor to estimate the parameters of an aeration model that accounts for both bubble and surface aeration contributions. The resulting model adequately represented THM removal over a range of experimental conditions, and included surface mass transfer coefficients as a function of airflow rate that accounted for changes in tank surface area and volume. The second part of the study developed a complete model of a real-world tank, which included chlorine decay and THM formation, and demonstrated that the model (developed in the laboratory) performed very well when applied to a real-world tank system. The last step of the research incorporated the aeration model into a distribution system hydraulic and water quality solver and demonstrated that aeration could have a significant impact on distribution system THM concentrations. The development and evaluation of the aeration model provide a modeling framework that can be used as part of a design and operational decision making framework associated with fine bubble aeration as part of a comprehensive THM mitigation strategy.

Committee: Dominic Boccelli PhD (Committee Chair); Dionysios Dionysiou PhD (Committee Member); James Uber PhD (Committee Member) Subjects: Environmental Engineering

MS, University of Cincinnati, 2012, Engineering and Applied Science: Materials Science

This thesis summarizes the research on two novel applications of Atmospheric Pressure Microwave Plasma (APMP) system, i.e. – (i) functionalization of carbon nanotube (CNT) materials, and (ii) disinfection of water contaminated by Bacillus globigii spores. During the first phase of the research, the APMP system was reengineered for functionalization of CNT ribbons – a unique nanomaterial synthesized at Nanoworld Labs at UC. The ribbon bridges the dimensional and property gap between carbon nanotubes and their macro scale applications, such as light weight composites, biomedical, electronic devices, etc. However in order to improve the performance of CNT ribbons, they have been functionalized with fluorocarbon films using APMP system. Time-of-flight secondary ion mass spectrometry (TOF-SIMS) characterizations have indicated the presence of CF2 as a repeating unit in the film. Further, atomic concentration of C, F and O and the type of bonding in film were studied through X-ray Photoelectron Spectroscopy (XPS). The functionalization on the ribbons may improve its performance in light weight composites and other macro-scale applications. During the second phase of the research, applicability of APMP system for decontamination of water containing Bacillus globigii spores was explored. Water samples were treated by various plasma gas (He + 1% H2, He, O2 and N2) effluents. The magnetron power level was varied between 250 W to 400 W. The results obtained indicate that He + 1% H2 and O2 as plasma gases were more effective than He or N2. Best disinfection results with APMP were obtained when the incident microwave power level was 325 W. Based on literature review and experimental observations, it is has been concluded that UV and reactive oxygen species are the most important contributing factors for elimination of B. globigii spores. These experiments indicate that APMP system can be successfully employed a variety of problems in materials processing and environmental e (open full item for complete abstract)

Committee: Vesselin Shanov PhD (Committee Chair); Dale Schaefer PhD (Committee Member); Mark Schulz PhD (Committee Member) Subjects: Materials Science