Master of Science, University of Akron, 2024, Civil Engineering

Cyanobacteria can release cyanotoxins in fresh water which are detrimental to human health and aquaculture. PAK-27 is an effective algaecide for managing excessive cyanobacterial harmful algal bloom (cHAB). However, cyanobacterial cell death can release intracellular nutrients that can lead to the growth of other undesirable algae and phytoplankton. This study assessed the combined impact of PAK-27 and Phoslock® to control the cHAB and the potential desorption of soluble reactive phosphate (SRP) from Phoslock®. Three different reservoirs in northeast Ohio were used as study areas to conduct the combined impact assessment with PAK-27 applied in quarter dose and full dose. Phoslock® was added in two sets of reactor jars in 200:1 ratio of lb. Phoslock®: lb. PO43- according to manufacturer's guideline. The efficacy of PAK-27 was also monitored in the presence of natural organic matter (NOM). Both doses of PAK-27 significantly decreased cyanobacteria cell within two days of algaecide application (p<0.05) in absence of NOM. Though the treatment amended with PAK-27 and Phoslock® exhibited a rebound in cyanobacteria growth between day 2 and day 7, the cyanobacteria was lower than that exhibited in control jars. As expected, jars which received algaecide treatment had increased level of extracellular microcystin-LR (p<0.05). Quarter dose PAK-27+Phoslock® performed better in SRP reduction for the first reservoir and full dose PAK-27+Phoslock® was effective in controlling SRP for the second and third reservoir over the two weeks study. However, Quarter PAK-27 alone worked better in reducing SRP on week two compared to Quarter PAK-27+ Phoslock® in the first reservoir. For the last two reservoirs, the NOM treated jars were effective in reducing SRP by day 14. This in conjunction with the rebound in SRP concentration would indicate that Phoslock® would not be a long-term solution unless applied multiple times, which is cost inefficient. Lake Rockwell water was used to find the (open full item for complete abstract)

Committee: Teresa Cutright (Advisor); David Roke (Committee Member); William H. Schneider IV (Committee Member) Subjects: Civil Engineering

PhD, University of Cincinnati, 2023, Engineering and Applied Science: Environmental Engineering

Natural organic matter (NOM) is a supramolecular aggregate formed by relatively small molecular assemblies through electrostatic, hydrophobic interactions and/or hydrogen bonds (H-bonds). The ubiquity of NOM renders it an unavoidable target for almost all studies associated with water treatment. However, the inherent complexity of NOM also makes it extra challenging to have detailed understanding of its roles in natural and engineered environmental systems. As a complex mixture, NOM aggregate molecular weight can range from several hundred to more than 100,000 Daltons, comprising of thousands of chemical constituents. Fortunately, with the effort of numerous scientists and advances of technology, it is now possible to characterize NOM from bulk to molecular level. Furthermore, by integrating certain mathematical analyzing methods, more patterns hidden behind the intricate NOM-involving system can be revealed. In this dissertation, a standard methodology was developed that incorporates the analytical probes with mathematical analysis techniques for the purpose of carrying out a comprehensive characterization of NOM, including algal organic matter (AOM), in any given water matrices and simultaneously elucidating the reaction mechanism between NOM and various other water constituents. In the process of achieving this goal, several tasks were accomplished. Firstly, NOM was fractionated based on two different criteria: molecular weight (MW) and hydrophilicity. However, this step is optional when the targeted NOM species are very specific. For example, during harmful algal bloom season (HAB), collected AOM species would not require fractionation since AOM is not as polydisperse as other NOM species unless fractionation is needed to study a particular property. Also, interaction between NOM/AOM and other compounds, selenium species to be specific was studied, and the interaction mechanism was investigated by adopting multiple characterization techniques suc (open full item for complete abstract)

Committee: Dionysios Dionysiou Ph.D. (Committee Chair); Xi Chen Ph.D. (Committee Member); Maobing Tu Ph.D. (Committee Member); Mallikarjuna Nadagouda Ph.D. (Committee Member); Dongmei Feng Ph.D. (Committee Member) Subjects: Environmental Engineering

Master of Science in Engineering, University of Akron, 2023, Chemical Engineering

Algal cyanobacteria can produce cyanotoxins in the surface water. The rise in cyanotoxins occurrence and concentration threatens animals and humans, making them a global environmental challenge. Powdered activated carbon (PAC) is a non-reactive and cost-effective option for the adsorption of cyanotoxins. The extent of adsorption is influenced by the properties of PAC, toxins, and surface water. This project focused on the removal of varying concentrations of microcystin-LR (MC-LR, 0.3, 1.6, and 20 μg/L) and saxitoxin (STX, 0.3 and 1.6 μg/L) with three different PAC sources. Experiments were performed with distilled water (pH 6 and 9) and natural water (pH 6, 8, and 9) when MC-LR and STX were present alone and simultaneously. Mixing rates of drinking water plant were scaled down to lab scale to replicate the rapid mix-flocculation by maintaining the same velocity gradient using a gang mixer. Additional tests were performed to find PAC's point of zero charge (pHPZC) to determine its overall surface charge variation with pH, which could affect adsorption based on cyanotoxin's charge. Source of PAC impacted removal of toxins. For instance, the wood-lignite-based PAC from CarbPure (CP) adsorbed more MC-LR than the bituminous coal-based PAC purchased from Calgon Carbon (CC) (p<0.05). Depending on the initial concentration, CP adsorbed 49-87% MC-LR in distilled water and 60-84% in raw water. CC only adsorbed 20-60% MC-LR from distilled water and 11-21% from raw water. In raw water across all pH and concentration combinations, STX removal was 16-80% with CP and 31-46% with CC. An experiment performed on 0.3 μg/L STX in distilled water with an additional PAC, Aquasorb (AS), had a removal trend of CP > AS > CC. The presence of multiple sources (AS and CP) may have enhanced adsorption. CP adsorbed (14-77%) more STX in distilled water than CC (21-49%) and AS (16-68%). When toxins were present simultaneously, CP effectively removed 48-72% MC-LR and 30-66% STX, depending upon the (open full item for complete abstract)

Committee: BI-MIN ZHANG NEWBY (Committee Member); LU-KWANG JU (Committee Member); TERESA CUTRIGHT (Advisor) Subjects: Chemical Engineering; Civil Engineering; Environmental Engineering

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, 2015, Geological Sciences

Polybrominated diphenyl ethers (PBDEs) are a class of brominated flame retardant that is ubiquitous in the environment and detected in a variety of both biotic and abiotic samples. Mounting concern over the last several decades over the toxic effects of PBDEs has resulted in a global cessation in their production. Nonetheless, PBDEs will continue to be detected in the environment due to their emission from ongoing use and recycling of PBDE-containing products. PBDEs are distally transported to the Arctic, but little is known about the fate of these compounds in Arctic surface waters, especially in the presence of dissolved organic matter (DOM). The present study is focused on quantifying the influence of DOM in the binding (i.e. dissolved organic carbon—water partition coefficients, KDOC) and abiotic photodegradation rates, mechanisms, and product formation of PBDEs under environmentally relevant conditions. My results indicate that PBDEs strongly bind to DOM, whereby the measured KDOC were nearly an order of magnitude lower than previously reported values for the same PBDE congeners in soil or commercially available organic matter. The KDOC values measured in the present study range from 103.97 to 105.16 L Kg-1 of organic carbon, which increase with congener hydrophobicity. This association with DOM facilitates PBDE photodegradation, resulting in at least a factor of 2 increase in rate constants for the indirect relative to direct photolysis of BDE-47. Photodegradation rates are strongly positively associated with DOM aromaticity and negatively correlated to dissolved oxygen. As such, photodegradation likely occurs via reduction reactions with excited triplet DOM and is expected to be insensitive to reactive oxygen species. Finally, the efficacy of fluence-based rate constants is explored for the direct comparison of experiments conducted under variable natural and artificial sunlight. Using the irradiance normalization method, discussed in t (open full item for complete abstract)

Committee: Yu-Ping Chin (Advisor); Kristopher McNeill (Committee Member); William B. Lyons (Committee Member); John Lenhart (Committee Member) Subjects: Environmental Science

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

Surface water contains natural organic matter (NOM) that reacts with disinfectants creating disinfection byproducts (DBPs), some of which are USEPA regulated contaminants. Characterizing NOM can provide insight with respect to DBP formation and water treatment process adaptation to climate change as the nature of NOM varies. This study collected NOM from the Ohio River over 15 months (April 2010 to July 2011) in order to assess seasonal variability in NOM characteristics. The NOM was characterized using fluorescence spectroscopy, UV254, TOC, high performance liquid chromatography – size exclusion chromatography (HPLC-SEC), and elemental analysis. NOM was concentrated, freeze-dried (lyophilized), and validated with the source NOM creating a standardized lyophilized NOM that may be used in water treatment process evaluations investigating utility adaptation to seasonal changes. Additionally, NOM was concentrated at multiple concentration factors, lyophilized, and reconstituted allowing for the determination of optimal NOM concentration and reconstitution conditions. The NOM was characterized using UV254, TOC, HPLC-SEC, fluorescence spectroscopy, and DBP formation. Raw Ohio River water NOM was concentrated in the following order: ultrafiltration (UF), cation ion exchange, reverse osmosis (RO), sulfate removal, and lyophilization. Lyophilization allows for long-term storage of NOM while providing the ability to reconstitute at various NOM concentrations compared to liquid material with a short shelf-life. Lyophilized NOM was used for elemental analysis while UF effluent, concentrate, and reconstituted lyophilized NOM were employed for all other analyses. A single RO concentration factor (150X) was used during the 15-month study while 50X, 100X, 150X, 200X, and 250X were used to determine the optimal RO concentration factor versus reconstitution factor. Parallel factor ii analysis (PARAFAC) determined the locations of principle components within fluorescence excitatio (open full item for complete abstract)

Committee: Dominic Boccelli Ph.D. (Committee Chair); Jonathan Pressman Ph.D. (Committee Member); Margaret Kupferle Ph.D. P.E. (Committee Member) Subjects: Environmental Engineering

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

The objectives of this study were to investigate the transformation of ICM as a function of pH (6.5 to 9.5) and time (up to either 72 or 168 hr) in the presence of chlorinated oxidants. Total organic iodide (TOI) loss was used as a surrogate for the ICM. Experiments were performed with and without natural organic matter (NOM). Degradation of TOI in the absence of NOM was carried out at low and high concentrations of iopamidol and aqueous chlorine. Also, the effect of NOM variation on iodate formation was investigated. The TOI degradation and iodate formation at low reactant and buffer concentrations were greatest at pH 7.5 and least at pH 9.5. TOI degradation followed observed first-order kinetics at all pH except pH 6.5, which exhibited bi-phasic degradation kinetics. Iodate formation did not follow either first or second order observed formation and was the predominant iodine-containing species after 24 hr. Furthermore, disinfection by-products (DBPs) formed at pH 6.5 – 8.5 were chloroform, trichloroacetic acid and chlorodiiodomethane. In the presence of monochloramine and in the absence of NOM, the loss of TOI was insignificant and no iodate formation was observed. At high concentrations of iopamidol and aqueous chlorine, TOI loss and iodate formation at pH 6.5 and 8.5 was rapid for the first 24 hr and ceased afterwards. The formation of total organic chloride (TOCl) was initially observed at 6 hr and 2 hr for pH 6.5 and 8.5 respectively. Also, chloroform, dichloroiodomethane, chlorodiiodomethane, dichloroacetic acid and trichloroacetic acid was observed. About 99% of the remaining TOI formed at each discrete time was contained in unidentified iopamidol transformation products. When TOI was monitored in the presence of NOM and aqueous chlorine, source waters from Akron, Barberton and Cleveland respectively recorded 68 to 74%, 62 to 72% and 68 to 77% loss of TOI. However, no iodate was formed in any of the source water experiments. No signifi (open full item for complete abstract)

Committee: Stephen Duirk PhD (Advisor); Lan Zhang PhD (Committee Member); Christopher Miller PhD (Committee Member) Subjects: Civil Engineering; Environmental Engineering

PhD, University of Cincinnati, 2011, Engineering and Applied Science: Environmental Engineering

Silver nanoparticles (AgNPs) have received an increased attention in the past decade. This is a result of their unique size-dependent physical and chemical properties and their broad-spectrum toxicity to organisms. The AgNPs have been incorporated in a range of consumer products and have various medical, scientific and industrial applications. Because the hypothesized mechanisms that govern the fate, transport and toxicity of bulk materials may not directly apply to materials at the nanoscale, there are great concerns in the regulatory and research communities about potential environmental impacts associated with the release of AgNPs into the environment. Therefore, the current study aimed at conducting fundamental research to characterize the surface charging and aggregation properties of coated and uncoated AgNPs under various environmental conditions, examine their aggregation kinetics, investigate their mobility in reactive and nor-reactive porous media and assess their toxicity to organisms. The selected AgNPs represent the various surface charging scenarios and the common stabilization mechanisms. The AgNPs were, 1) electrostatically stabilized (uncoated H2-AgNPs, Citrate-AgNPs and NaBH4-AgNPs), 2) sterically stabilized (Polyvinylpyrrolidone coated (PVP-AgNPs)) and 3) electrosterically stabilized (branched polyethyleneimine coated (BPEI-AgNPs)). The type of capping agent and environmental conditions (pH, ionic strength and background electrolytes) had a great impact on the surface charge and aggregation potential of AgNPs. The electrostatically stabilized AgNPs aggregated at high ionic strength, acidic pH conditions and in the presence of divalent cations regardless of the pH. The ionic strength, pH and electrolyte valence had no impact on the surface charge and aggregation of the sterically stabilized AgNPs. This was not the case for the electrosterically stabilized AgNPs which exhibited major changes in surface charge and particle size as a result of the var (open full item for complete abstract)

Committee: Makram Suidan PhD (Committee Chair); Thabet Tolaymat PhD (Committee Member); Dionysios Dionysiou PhD (Committee Member); George Sorial PhD (Committee Member) Subjects: Environmental Engineering

Master of Science, The Ohio State University, 2010, Environmental Science

Ultrasound at a frequency of 20 kHz and a power of 16 W was applied to a cross-flow ultrafiltration system to investigate the ultrasonic control of surface-water fouled ceramic membranes. Also, the impact of solution chemistry on fouling in the absence and presence of ultrasound was studied. Ultrasound was effective in improving the normalized permeate flux from 0.21 in the absence of ultrasound to 0.70 with the aid of ultrasound. Moreover, a stable permeate flux was obtained throughout the 2 hour filtration process, which is important for maintaining satisfactory production. Parameters of solution chemistry we investigated had little impact on membrane fouling in the absence of ultrasound (in terms of both fouling rate and fouling extent); however, Ca and pH played more important roles in ultrasonic fouling control: lower calcium concentration and moderate pH values were more amenable to ultrasonic control. This difference in fouling behavior between ultrasound and no ultrasound conditions was attributed to the different factors controlling membrane fouling in the presence and absence of ultrasound. Further investigation of NOM fractions suggests that the hydrophilic fraction dominated fouling behavior in the absence of ultrasound, and the ultrasonic control was mainly affected by foulant-foulant and foulant-membrane interactions, which were presumably controlled by the adsorption or binding effects in the hydrophobic fraction. NOM fractionation experiments revealed that fouling in the absence of ultrasound by the hydrophilic fraction was less dependent on calcium concentration and pH. On the other hand, for ultrasonic control, lower calcium concentration, and moderate pH increased the cleaning efficiency probably due to weaker foulant-foulant and foulant-membrane adhesion caused by less humic adsorption and binding effects.

Committee: Linda Weavers (Advisor); Harold Walker (Advisor); John Lenhart (Committee Member); Yu-Ping Chin (Committee Member); Dong Chen (Committee Member) Subjects:

Doctor of Philosophy, The Ohio State University, 2009, Civil Engineering

The presence of cyanobacteria and associated cyanotoxins in surface water is of increasing concern. Microcystins are one of the most dangerous and commonly occurring classes of cyanotoxins. Ingestion of microcystin-LR can lead to liver damage and the promotion of liver tumors. Due to adverse health effects, the World Health Organization set a guideline level of 1 part per billion (ppb) for microcystin-LR in drinking water. However, current water treatment facilities may not specifically treat drinking water for microcystins. The overall goal of this research was to develop an advanced and effective process for the removal of microcystins from drinking water. To achieve this goal, powdered activated carbon (PAC), iron oxide nanoparticles, and ultrafiltration (UF) membranes were explored as promising treatment technologies. The use of ultrafiltration was investigated for the rejection of microcystin-LR from drinking water. Adsorption dominated rejection for most UF membranes, at least at early filtration times, while both size exclusion and adsorption were important in removing microcystin-LR by the tight thin-film membranes. The extent of membrane adsorption was generally related to membrane hydrophobicity. The application of ultrafiltration coupled with powdered activated carbon (PAC-UF) was also investigated. Of the two different PAC materials, wood-based activated carbon was more effective at removing microcystin-LR than coconut-based carbon due to greater mesopore volume. The PAC-UF system had the highest removal efficiency among the three processes (i.e., PAC adsorption, ultrafiltration, and PAC-UF) for both hydrophobic polyethersulfone (PES) and hydrophilic cellulose acetate (CA) membranes. When PAC was coupled to UF using PES membranes, greater removal of microcystin-LR occurred compared to when CA membranes were used, due to sorption of the toxin to the PES membrane surface. In further studies, Suwannee River Fulvic Acid (SRFA) was used to examine the effe (open full item for complete abstract)

Committee: Harold Walker (Advisor); Linda Weavers (Committee Member); John Lenhart (Committee Member); Yu-Ping Chin (Committee Member) Subjects: Chemical Engineering; Chemistry; Civil Engineering; Engineering; Environmental Engineering; Environmental Science; Geochemistry

Doctor of Philosophy, The Ohio State University, 2005, Civil Engineering

This study systematically investigated the mechanism and efficiency of the ultrasonic control of gamma-alumina ceramic membrane fouling caused by silica particles and dissolved organic matter (DOM). Ultrasound at 20 kHz was applied to a cross-flow filtration system. First, ultrasonic cleaning was explored with filtration of silica particles to investigate influence of both particle characteristics and ultrasonic factors on cleaning. Experimental results indicated that more effective control of fouling occurring at low particle concentrations, hydrophilic particles, and large particle sizes based on measurements of sound wave intensity, images of the cavitation region, and force balance analysis of a particle deposited on the membrane. In addition to the effect of particle characteristics, ultrasonic factors affecting membrane cleaning were explored. Optimal cleaning occurred when the membrane was outside but close to the cavitation region. However, damage in the form of pits and cracks were found when the membrane was within the cavitation region. An increase in the filtration pressure resulted in less improvement in permeate flux of ultrasound. Furthermore, pulsed ultrasound with short pulse intervals resulted in a relative permeate flux improvement close to that of continuous sonication. Second, besides sonophysical cleaning of particle fouled membranes, membrane cleaning was also explored by studying sonochemical reactions of DOM. Property changes of Aldrich and Pahokee peat DOM at different ultrasonic frequencies and energy densities were systematically investigated. Exposure of DOM to ultrasound resulted in decreases in hydrophobicity, aromaticity, and molecular weight, while DOM acidity increased. However, at low ultrasonic frequency (20 kHz) and low energy density, sonochemical transformation of DOM was insignificant. Finally, the effect of solution chemistry on ultrasonic control of membrane fouling caused by DOM and silica particles was examined. Experiment (open full item for complete abstract)

Committee: Linda Weavers (Advisor) Subjects: Engineering, Environmental

Master of Science in Engineering, University of Akron, 2010, Civil Engineering

Natural aquatic organic matter (NOM) reacts with chlorinated disinfectants used to treat public drinking water supplies resulting in the formation of toxic and carcinogenic disinfection byproducts (DBPs). Therefore, treatment processes that reduce the concentration of NOM prior to drinking water disinfection have been found to reduce the formation of these unwanted DBPs. Conventional enhanced coagulation was compared with a novel anion exchange resins for reducing DBP precursors located in the negatively charged fraction of the NOM matrix. Three anion exchange resins (AERs) were compared (IRA-910, IRA-958, and MIEX) to determine which resin would not only remove NOM but DBP precursors as well. All the AERs were found to be highly proficient at NOM reduction specifically the moieties that absorb UV light at 254 nm and 272 nm over 75 minutes of contact time; however, MIEX removed NOM at a faster rate than the Amberlite resins. Results show that pH had no significant effect on the removal of chromophores and fluorophores (i.e. EEM base pairs A and C) when treated with MIEX or enhanced coagulation. Coagulation was effective at removing 30-45% NOM for Akron and Barberton source waters based on peak intensity excitation-emission pairs taken from the EEM (excitation- emission matrix). Peak intensity in the T region of the EEM for the Barberton source water, which correlates to positively charged soluble microbial, was found to be relatively resilient to each NOM removal process. DBP formation was determined as a function of pH for the different NOM removal processes. MIEX resulted in significant reduction in DBP concentrations for both source waters when compared to DBP formation in the chlorinated raw source waters. MIEX out performed both coagulants reducing the formation of DBPs in both source waters. At an elevated chlorine concentration in the raw samples, as pH increases from 6.5 to 8, chloroform formation increases, TCAA concentrations decrease and dichloroacetic a (open full item for complete abstract)

Committee: Stephen Duirk Dr. (Advisor); Christopher Miller Dr. (Committee Member); Zhang Lan Dr. (Committee Member) Subjects: Environmental Engineering