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This thesis presents innovative multiphysics Computational Fluid Dynamics (CFD) modelling approaches for the removal of water contaminants of emerging concern (CECs) in micro, bench, pilot and industrial scale photoreactors by Advanced Oxidation Processes (AOPs). One major reason for the slow penetration of photochemical AOPs in the industry has been the complex numerical description of these systems, thus, in this thesis high-fidelity solutions are proposed by coupling the fluid dynamics, the species transport, the kinetics and the transport of radiation in the photoreactors. The AOPs systems studied included the degradation of common pharmaceuticals (Acyclovir, Stavudine, Zidovudine, Methylisothiazolinone, Benzisothiazolinone and Isoxazole) by the H2O2 process in helical microcapillary film photoreactors (MCF), the removal of CECs (O-desmethyltramadol, O-desmethylvenlafaxine and gabapentin) in pilot and large-scale solar photo-Fenton raceway pond reactors (RPR) and the photocatalytic oxidation of 2-hydroxybenzoic acid in bench-scale annular and flat channel photoreactors. The most relevant transport phenomena in each case study were identified and answers to gaps in the literature were provided. This study provided tailored model hypotheses of fundamentally different AOPs, photoreactors and reactor scales to reduce the computational cost of the simulations while maintaining a high-fidelity of the model results. These approaches and hypotheses were validated by comparisons with experimental results of hydrodynamics and removal rate of the water contaminants. The UV/H2O2 process in a helical shaped MCF was studied to unveil the impact of secondary flow (Dean Vortices) on radial mixing and process intensification in a safe, ultrafast and controlled microreactor environment. This was achieved using a 10-fold less CPU-demanding CFD model that neglected the torsion effects in the helical MCF. Although the UV/H2O2 process has reached full-scale applications, accurate estimations of intrinsic kinetics constants are needed, and this thesis showed how CFD modelling can be used to determine highly accurate kinetics constants necessary to design efficient UV/H2O2 photoreactors. The CFD modelling of pilot and large-scale solar photo-Fenton RPRs was performed to evaluate the impact of mixing and hydrodynamics on the removal of CECs from a real secondary Wastewater Treatment Plant (WWTP) effluent. A multiphysics CFD modelling of the solar photo-Fenton process was shown for the first time, and a 41-fold less CPU-demanding model was proposed using momentum source domain rather than a transient-multiphase solution. The interest in the requirements use of RPRs for the treatment of secondary WWTP effluents by the solar photo-Fenton process has increased in recent years, and this study revealed that the design of hydrodynamics in large-scale RPRs must be carefully examined to reduce power consumption while increasing mixing performance. Lastly, CFD was used to the determine intrinsic kinetics constants of the photocatalytic oxidation of 2-hydroxybenzoic acid in TiO2 suspension in an annular and in a flat channel photoreactors. The Local Volumetric Rate of Photon Absorption (LVRPA) was computed by solving the Radiative Transfer Equation (RTE) using the Six-Flux model (SFM) and the Discrete Ordinates Model (DOM). Results showed, for the first time, that refractive and reflective phenomena should not be neglected when using DOM, however, SFM provided fairly accurate evaluations of the LVRPA, the Electrical Energy Per Order Reduction (EEO) and estimations of the optimal optical thickness. This gives SFM a significant advantage for reactor design investigations, since it can calculate the LVRPA in few seconds in a personal computer, while the DOM requires parallel processing in several minutes/hours. In summary, this thesis established CFD as a fundamental tool for the computation of highly accurate kinetics parameters, for the comparison of different photochemical AOPs, for example by the estimation of the EEO, and for AOPs intensification. Deviations from the ideal flow reactors (e.g., plug flow or perfectly mixed) were disclosed at micro and macro-scale photoreactors, and the conditions to diminish mass transfer limitations were identified. The combined approach of experimental and numerical simulations is crucial to accomplish the design of reliable photochemical AOPs in industrial scale, and this thesis has strengthened the use CFD simulations of AOP photoreactors by the proposition of modelling simplifying hypotheses at different photoreactor scales.

Nowadays, water scarcity, deterioration of source water, and the more stringent water quality requirements are the primary driving forces for the development of novel and robust purification processes to make the most use of the limited water resources. Ultraviolet (UV) -based advanced oxidation processes (UV-AOPs) have been intensively studied and have started to be implemented in full scale potable water treatment facilities due to their high efficiency in the degradation of contaminants of emerging concern (CECs). Compared with the well-studied UV/H2O2 process, the UV/chlorine process, by integrating chlorination and UV irradiation, draws increasing attention due to its wider application range and higher cost-efficiency, and has been proposed and implemented as an alternative to UV/H2O2 in pilot and full-scale drinking water treatment facilities.Chlorination is the most widely applied disinfection process. By dosing free active chlorine (FAC) to the water treated by coagulation and filtration, chlorination can inactivate waterborne pathogens and degrade various organic pollutants. However, the CECs degradation by chlorination was not efficient with the practical chlorine exposure (Ct value). Decontamination by chlorination suffers from a ubiquitous, pernicious trade-off: enhancement of chlorination by increasing chlorine exposure by either increasing chlorine dosage or prolonging contact time, leads to unintended toxic consequences, including a greater yield of disinfection by-products (DBPs) and chlorinated transformation products. This dissertation provides a comprehensive assessment of using UV/chlorine as an emerging treatment to overcome this trade-off. Frequent and severe occurrences of harmful algal blooms (HABs) pose a risk to human health due to the production of algal toxins with high hepatotoxicity profiles, especially microcystins (MCs). In this study, the degradation and detoxification of the four most ubiquitous MCs with different amino acid moieties, i.e., MC-LR, MC-RR, MC-YR, and MC-LA, using the UV/chlorine process was assessed with chlorination treatment as the baseline. The roles of specific amino acid moieties of corresponding MC variants on the degradation kinetics, pH, and cytotoxicity during the treatment were investigated. The natural presence of Cl– in surface water emphasizes the need to consider Cl– in the treatment processes. The chlorine speciation profile at different levels of Cl– was simulated with consideration of ionic strength. With the existence of Cl–, an exotic chlorinating agent, Cl2(aq) enhanced both chlorination and UV/chlorine kinetic rates. The concentration of Cl2(aq) was simulated in the current study. The second-order kinetic constants between Cl2(aq) and amino acids and MCs were reported for the first time.Since MCs usually occur jointly in a HAB event, mixed MCs were studied in various water matrices. The competition reactions of the mixed MCs and kinetic studies showed an identical trend of reactivities (MC-YR> -RR > -LR> -LA) in either chlorination or UV/chlorine.Cytotoxicity results indicated that the transformation by-product in UV/chlorine did not contribute to significant unintended toxic consequences. Analysis results from chlorinated transformation by-products, total organic halides (TOX), and disinfection by-products (DBPs) complied with this conclusion. Overall, UV/chlorine achieves greater degradation efficiencies of MCs with neglectable unintended toxic consequences and is a reliable drinking water barrier against HAB events.

Harmful algal blooms (HABs), resulting from the overgrowth of cyanobacteria and eukaryotic algae, pose increasing threats to water supplies and public safety due to the deterioration of water quality and potential production of toxic compounds. As human activities and climate-driven changes in environmental conditions may favor bloom formation, robust management strategies need to be developed to mitigate the adverse impacts of HABs. Coagulation and flocculation are essential components of drinking water treatment and are designed to remove the majority of algal cells along with the downstream clarification and filtration steps. In addition, coagulation-based processes have demonstrated great potential as in-lake intervention strategies to mitigate eutrophication and control algal blooms. The first part of this dissertation is dedicated to a comprehensive review of coagulation-based techniques for algae removal and control. In particular, introductory sections present the common algae of interest to water management and outline the theoretical background of interfacial phenomena in the coagulation system. Commonly used experimental methods and emerging techniques in coagulation studies are summarized with representative results. In addition, inorganic and organic coagulant materials of synthetic or natural origins and their applications in algae removal are discussed in depth. The latest developments in enhanced algae removal, propelled by electrochemical processes and sonication, are presented with fundamental technical concepts. Furthermore, practical considerations for using coagulation to remove algae in both water treatment facilities and natural waterbodies are discussed in detail with results from pilot- and full-scale studies.The second part of this dissertation focuses on photocatalysis-driven advanced oxidation processes to remove contaminants of emerging concern in water. Bismuth tungsten (Bi2WO6) photocatalysts were synthesized by a facile hydrothermal approach. By manipulating the ratio of bismuth and tungsten precursors, plate-like hierarchical clusters with multiple layers of stacked smaller nanoplates were fabricated. A surface-decorated Z-scheme heterojunction was constructed within the stacked nanoplates following a controlled surface modification process. The morphological, structural, and optical properties of Bi2WO6 photocatalysts were studied with various characterization techniques. The photonic efficiencies of Bi2WO6-based photocatalysts were determined under UV-visible light and visible-only light and compared with the benchmark P25 TiO2 photocatalyst. The major reactive species and photocatalytic reaction mechanism were elucidated with various characterization and analytical results. The photocatalytic activity in complex water matrices was evaluated with varying water parameters, including pH, inorganic ions, and natural organic matter. The Z-scheme photocatalyst was shown to effectively remove several CECs, including cyanotoxins, and pharmaceuticals and personal care products.

Abstract: One of the most serious issues associated with the oil sands production is the generation of large volumes of oil sands process water (OSPW). OSPW is a highly complex mixture of sands, silts, salts, heavy metals, and refractory organic compounds. Currently, OSPW is retained on site in large tailings ponds and there is no active return to the regional watershed. Therefore, there is an urgent need to develop water treatment processes for the safe release of treated OSPW into the environment. In this thesis, novel separation methods were developed to isolate and fractionate OSPW inorganics and organics that allowed more accurate and comprehensive study on the characterization, influence and degradation of each OSPW fraction by ozonation or photo-oxidation. OSPW organic fraction (OSPW-OF) was extracted by solid phase extraction (SPE) and OSPW containing only inorganic fraction (OSPW-IF) was obtained after the organic compounds were adsorbed by granular activated carbon (GAC). SPE using hydrophilic lipophilic balanced (HLB) cartridge combined with methanol elution achieved the highest dissolved organic carbon (DOC) (95.4%) and NA (90.0%) recovery as compared with other tested cartridges and liquid-liquid extraction (LLE) with dichloromethane. A recovery higher than 80.0% for each NA species was achieved using HLB cartridge with methanol elution. After passing through GAC cartridge, 96.1% of DOC in OSPW was adsorbed. The difference of pH, alkalinity, conductivity, and the concentrations of detected ions in OSPW and GAC cartridge effluent were negligible. Thus, GAC adsorption was found to be a promising method to obtain OSPW-IF representable of real OSPW. A silver-ion SPE approach was utilized to separate OSPW NAs into 20 fractions with aliphatic O2-NAs, aromatic O2-NAs, O3-NAs, and O4-NAs dominated in different fractions. Ozonation of these fractions was conducted to study the ozonation reactivity of isolated aromatic and oxidized NA species. The removals of aliphatic O2−NAs fraction, aromatic O2−NAs fraction, O3−NAs fraction, and O4−NAs fraction with an applied ozone dosage of 16.8 mg/L were 97.2%, 94.7%, 59.4%, and 44.7%, respectively. Aromatic and oxidized NAs (O3−NAs and O4−NAs) with larger carbon number were favorably removed during ozonation treatment. A comparison of the ozone utilization efficiency for different NA species indicated that the degradation of oxidized NAs consumed more ozone in molar ratio than the degradation of aliphatic and aromatic O2-NAs, which resulted in the lower reactivity of oxidized NAs than that of O2-NAs. OSPW-IF adversely affected the ozonation of a model compound cyclohexanecarboxylic acid (CHA) by competitively consuming ozone. Main inorganic ions present in OSPW were separately added into CHA in buffer solution to investigate their individual influence on the ozonation of CHA. NH4+, Mn2+, HCO3- and Cl- showed slight reduction on CHA degradation. In addition, higher NA degradation was observed after the ozonation of extracted organics dissolved in buffer than the ozonation of OSPW, which demonstrated that the inorganics in OSPW inhibited the degradation of NAs during OSPW ozonation process. Moreover, ozonation of non-filtered and filtered OSPW showed that there was a negligible influence of particles on the ozonation of NAs. The results from this research suggested that ozonation would be better utilized as an intermediate or post treatment process in a treatment train for OSPW remediation and intermittent ozonation might achieve higher ozone utilization than the continuous ozonation process. Direct photolysis of OSPW was conducted to investigate the photodegradation of NAs in OSPW without adding external catalysts. It was observed that 60 min of direct UV exposure of OSPW with the irradiance intensity of 2.92 mW/cm2 achieved the removal of O2-, O3-, and O4-NAs to be 46.4%, 11.2%, and 9.9%, respectively, which were higher than the degradation of extracted organics dissolved in buffer. This indicated that the presence of inorganics in OSPW enhanced the photodegradation of NAs. Meanwhile, the effect of OSPW-IF on the photodegradation of model NA, 1-adamantanecarboxylic acid (ACA,) was studied. A 34% of ACA was removed in the presence of OSPW-IF, while no ACA degradation was observed in buffer solution after 60 min of UV exposure. The results indicated that OSPW-IF induced the photodegradation of ACA. Individual ions present in OSPW were added into ACA in buffer solution to clarify whether the inorganic species in OSPW could act as photosensitizers. Nitrate had demonstrated to be an active ion present in OSPW that induced the photodegradation of ACA. In the presence of nitrate, both hydroxyl radicals (•OH) and reactive nitrogen species (•NO, •NO2) were generated, where •OH was the dominant reactive species that contributed to the degradation of ACA. Ten by-products including single and multiple hydroxyl, nitro, nitroso and carbonyl substituted by-products were proposed to be produced from the nitrate induced photodegradation process through three different pathways.

Iron oxide nanoparticles (IONPs) have been widely studied for a variety of applications, from biomedical applications (e.g., cell separation, drug delivery, contrast agent for magnetic resonance imaging and magnetically mediated energy delivery for cancer treatment) to environmental remediations (e.g., heavy metal removal and organic pollutants degradation). It has been demonstrated that IONPs can induce the production of reactive oxygen species (ROS) via Fenton/Haber-Weiss reactions which has been shown to be one of the key underlying mechanisms of nanoparticles toxicity. This inherent toxicity of nanoparticles has been shown to enhance the efficacy of traditional cancer therapies such as chemotherapy and radiation. In addition, the generation of ROS induced by IONPs has been also studied as advanced oxidation processes (AOP) for wastewater treatment. Recent research has also shown that exposure to an alternating magnetic field can significantly enhance the generation of ROS induced by IONPs. Moreover, the coatings of IONPs play an important role on the surface reactivity of nanoparticles since it can prevent the generation of ROS via Fenton chemistries at the surface of the nanoparticles. In this work, co-precipitated IONPs were functionalized with small molecules including citric acid, sodium phosphate, amino silane and dopamine. The impact of coating on surface reactivity of the as-synthesized particles was studied using methylene blue dye degradation assay under AMF exposure. With the coatings of these small molecules, the IONPs induced ROS generation was significantly decreased because of the dense surface coverage. To study the effect of polymeric coatings, a degradable poly (beta amino ester) (PBAE) polymer coating was synthesized with dopamine as an anchor to bind to nanoparticles. The surface reactivity of the particles was expected to be recovered once the polymer coating was degraded. Furthermore, the impact of non-degradable PEG-based polymer coating on surface reactivity via ROS generation was also investigated using methylene blue decolorization assay with the presence of AMF. The retention of surface reactivity of PEG-based polymer coated IONPs shows promise for cancer treatment. The application of IONPs as heterogeneous catalyst for organic contaminant degradation was investigated. Bisphenol A (BPA) was used as a model compound, and Fenton reactions were induced by IONPs with the presence of hydrogen peroxide and hydroxylamine as well as alternating magnetic field exposure. The kinetics of BPA degradation under water bath and AMF exposure at 37oC was also studied, and the results showed potential applications of IONPs for organic pollutants remediation.

Disinfection byproducts (DBPs) presence in wastewater effluents and receiving waters may impact the quality of drinking water during water reuse practices. Natural solar photolysis is one of the biogeochemical processes that may lead to decreased DBPs concentrations in water. The purpose of this dissertation is to determine the fate of chlorinated, brominated and iodinated DBPs in surface water by natural sunlight photolysis and investigate the use of solar-based advanced oxidation processes (AOPs) for removal of DBPs in water. Total organic halogen (TOX) was used to measure total chlorinated- (TOCl), brominated- (TOBr) and iodinated-DBPs (TOI) in water. The first objective was to determine the optimum protocol for TOX sample preservation conditions to ensure accurate TOX analysis throughout the following experiments. To achieve the highest TOX recovery, samples must be stored at pH 2 using nitric acid, 4 °C incubator and be analyzed within 14 days of storage. Overdosing of quenching agents such as sodium sulfite, sodium thiosulfate and ascorbic acid must be avoided to maintain stable TOX concentrations during storage. The second objective was to determine the fate of TOCl, TOBr, TOI and individual DBPs by natural sunlight in surface water. Iodinated DBPs were the most photodegradable specific halogenated DBPs, whereas chlorinated DBPs were the most resistant to sunlight photodegradation. The TOX degradation rates were generally in the order of TOI > TOBr TOCl(NH2Cl) > TOCl(Cl2) and the half-lives ranged between 2.6 and 10.7 h during solar photolysis. Typical concentrations of natural surface and wastewater containments including nitrate, nitrite and sulfite had little impact on enhancing DBPs photodegradation rates. However, natural organic matter and turbidity decreased photodegradation of DBPs by light screening. The third objective was to evaluate the use of solar-based AOPs for DBP removal in water. Both solar-TiO2 photocatalytic and solar photo-fenton processes increased DBPs photodegradation rates significantly in comparison to solar photolysis alone. TOX half-lives were reduced from hours to minutes by the two solar-based AOPs, and the rate of degradation were generally in the order of TOI > TOCl(NH2Cl) > TOBr > TOCl(Cl2). Oxidation by hydroxyl radicals is expected to be the main mechanism accountable for improved DBP degradation. Furthermore, several natural water constituents including chloride, sulfate, natural organic matter and bicarbonate decreased DBPs degradation efficiency by solar-based AOPs.

Contaminants of emerging concern (CECs) are being detected frequently in surface waters and treated wastewater effluent, which stimulates environmental concern on human and ecological health. Effective and environment friendly approaches such as advanced oxidation processes (AOPs) are desirable for the wastewater treatment processes. In this research, the degradation kinetics, pathways, and cytotoxicity of CECs in the UV/hydrogen peroxide and UV/nitrate were investigated, as well as the degradation mechanisms of atrazine in UV-vis/ferrite/sulfite AOP were investigated.UV/hydrogen peroxide could simultaneously remove multiple CECs at high rates in Milli-Q water. Field water samples from Orange County Water District were used as reaction matrices with spiked additions of chemicals to evaluate the performance of UV/hydrogen peroxide, namely raw water from Santa Ana River, secondary effluent, microfiltration effluent, reverse osmosis (RO) permeate. Impacts of general water parameters on the degradation of mixed CECs were investigated, including pH, bicarbonate, nitrate, natural organic matter, chloride, free chlorine, and chloramine. The transformation products were monitored during the individual degradation of bisphenol A, diclofenac, ibuprofen, triclosan, and estrone in UV/hydrogen peroxide. The cytotoxicity, aryl hydrocarbon receptor (AhR)-binding activity, and estrogen receptor (ER)-binding activity were analyzed, including the degradation of single CEC in Milli-Q water and the removal of mixed CECs in field water samples.UV/nitrate can remove CECs due to the generation of hydroxyl radical and reactive nitrogen species (RNS), which is significantly affected by the presence of bicarbonate via quenching hydroxyl radical and forming carbonate radical. The addition of bicarbonate selectively enhanced the degradation of CECs with electron-rich moieties, such as phenolic group (bisphenol A, triclosan, estrone, and 17a-ethynylestradiol) and aromatic amine group (diclofenac), but inhibited the removal of CECs with less electron-donating moieties (atrazine, carbamazepine, and ibuprofen). The contributions from UV photolysis, and the oxidation of hydroxyl radical, carbonate radical, and RNS to the CEC decomposition in UV/nitrate with and without the addition of bicarbonate were evaluated. The transformation products were detected during the individual degradation of bisphenol A, diclofenac, triclosan, and estrone in UV/nitrate/bicarbonate to elucidate the change in cytotoxicity of resulting solutions. In addition, the RO permeate was used as reaction matrix with spiked additions of chemicals to evaluate the possible applications of UV/nitrate/bicarbonate in nitrate/carbonate-rich water reuse scenarios. Sulfate radical was generated through a novel AOP, photo-catalyzing sulfite by zinc-copper ferrites under UV-visible light, to remove atrazine from waters. Zinc-copper ferrite materials, synthesized through the sol-gel method, were fully characterized. The zinc-copper ferrite with the ratio of zinc to copper as 4:1 obtained the highest activity to catalyze sulfite to produce sulfate radical as the main reactive species. Reaction mechanisms to generate reactive species, including hydroxyl and sulfate radicals, and the degradation pathways of atrazine were investigated. No sulfite remained after complete removal of atrazine, and catalysts could be magnetically recovered, suggesting the UV-vis/ferrite/sulfite method is a “green” AOP, which has the potential to be applied in wastewater in the future.

Irradiation by UV-254 nm is a popular and efficient approach for disinfection in water and/or wastewater treatment plants. With the addition of oxidants such as hydrogen peroxide, persulfate, or chlorine into UV irradiation, the removal efficiency can be improved and synergistic degradation can be achieved through the formation of reactive radicals, such as hydroxyl radical, sulfate radical, reactive chlorine species, etc. Some of the radicals are non-selective (e.g., hydroxyl radical), while others are solely reactive to specific organic compounds. UV-based advanced oxidation processes (AOPs) for the decomposition of chemicals of emerging concern (CECs) were investigated in this dissertation. The utilization of UV/peroxide and UV/persulfate for iodinated pharmaceuticals (e.g., thyroxine and diatrizoate) and dibutyl phthalate (DBP) elimination in wastewater, and UV/chlorine for cyanotoxin microcystin–LR (MC-LR) degradation in drinking water, with the UV dose in the range applied in typical UV disinfection treatment units, were discussed. Both kinetic and mechanistic studies on the degradation of those chemicals were conducted in this study.UV/chlorine was evaluated as a potentially practical technique for the degradation of MC-LR. Compared to sole UV irradiation or chlorination, the combined process significantly lowered the chemical and energy demand, which was attributed to the generation of reactive radical species such as hydroxyl radicals, as demonstrated using various radical probes. The enhanced performance was also achieved at different pH conditions, with different oxidant dosages, and by using various natural water sources as background matrix. Via mass spectrometry analysis, products of hydroxylation, chlorination, isomerization, photohydration, as well as bond cleavage were identified during the decomposition, with fewer chlorinated MC-LR products by UV/chlorine than chlorine alone. The trends of disinfection byproducts formation were different immediately following treatment when compared after 24 hours of dark reaction when sand filtered natural water was used as a background matrix. The UV/chlorine treated samples also showed microscopically and biochemically less cytotoxicity in vitro in HepaRG human liver cell line tests than the samples treated by chlorine alone. Similarly, UV/persulfate achieved better degradation of iodinated pharmaceuticals and phthalate esters than UV/peroxide. When biologically treated wastewater samples were used as reaction matrices, the destruction of the contaminants was still efficient in the presence of radical scavengers. Hydroxylation, and C-I and C-O bond cleavage were the major pathways in the decomposition of thyroxine; while hydroxylation, dealkylation, quinone formation, hydrolysis, and decarboxylation occurred in plasticizer DBP degradation.Besides conventional UV lamps, newly invented multi-wavelength UV-LEDs were introduced and evaluated to reduce energy consumption, and to provide a more cost-effective strategy for the destruction of CECs. The activation of persulfate or chlorine can be achieved not only by UV-254 nm but also by higher wavelengths, indicating that medium pressure UV, which is more commonly installed in water treatment utilities, can remove CECs when coupled with photoactivatable oxidants. The study is anticipated to provide options for water/wastewater treatment facilities equipped with UV units to make slight changes to the current treatment processes to achieve satisfactory removal of CECs.

Abstract: Appling ozone (O3) with high doses (>100 mg/L) to remove naphthenic acids (NAs) from oil sands process-affected water (OSPW); limits its application and feasibility in the OSPW remediation. To decrease the required doses and their associated costs, this study examined the application of ozone (O3) and peroxone (hydrogen peroxide/ozone; H2O2:O3) processes for the treatment of OSPW using mild oxidant doses (i.e., ozone doses of 30 and 50 mg/L and H2O2 doses of 10, 11 and 20 mg/L). The performance of both processes was compared in terms of structure reactivity of NAs, the dominant pathways for removal, the kinetics of individual NA species and variation of compositions and abundance of species before and after treatment. To attain/ensure better characterization for the contaminants of concern (NAs) in water samples, the initial phase of this research encompassed examining two different analytical methods (Fourier transform infrared (FTIR) spectroscopy and ultra-performance liquid chromatography time-of-flight mass spectrometry (UPLC-TOFMS)) with different extraction/pre-treatment methods for samples; liquid-liquid extraction (LLE) and solid-phase extraction (SPE). A correlation between these methods was developed to implement the best techniques available for sample analysis. The results after examining groundwater and OSPW samples showed higher recovery of classical and oxidized NAs or (Ox-NAs) and naphthenic acid fraction compounds (NAFCs) for SPE compared to LLE, regardless the water source and quantification methods (i.e., FTIR and UPLC-TOFMS). However, higher abundance for classical NAs (O2-NAs) was found in LLE than SPE (e.g., OSPW samples: (63.1±2.1%) versus (58.5±3.0%)). A strong correlation was observed between the UPLC-TOFMS and FTIR which highlights the possibility of using FTIR and Fluka as a standard with LLE pretreated samples as an affordable substitute to the high resolution techniques (e.g. UPLC-TOFMS). In the second phase of this research, the structure reactivity and reaction pathways during ozonation and peroxone treatment were investigated. Suppressing the hydroxyl radical (•OH) pathway by adding the scavenger tert-butyl alcohol did significantly reduce the degradation in all treatments, while molecular ozone contribution was 50% and 35% for O2-NAs and Ox-NAs, respectively. Structure reactivity was observed with a degradation increase for both O2-NAs and Ox-NAs with the increase of both carbon (n) and hydrogen deficiency (i.e., |-Z| numbers, double bond equivalent (DBE)) for all treatments. The variations in the compositions of treated water were evaluated using two different high resolution mass spectrometry methods; UPLC-TOFMS and Fourier transform ion cyclotron resonance. Assessing two markers (O2S:O3S:O4S and O2:O4 ratios) revealed changes and similarities of the peroxone treated water (i.e., 20 mg/L H2O2: 50 mg/L O3 at 1:2 ratio) to natural waters. Both ratios decreased from 2.7:4.8:2.1 and 3.59 in raw OSPW to 0:1.4:0.5 and 0.7, respectively, becoming close to the reported ratios in natural waters. Although peroxone (1:2) 20+50 (i.e., 20 mg/L H2O2: 50 mg/L O3) and 50 mg/L ozone were the two most effective treatments to degrade O2-NAs and Ox-NAs (e.g., for O2-NAs: 86% and 84%, respectively) as well as to reduce the toxicity toward Vibrio fischeri (40% and 50%, respectively), the fastest kinetics treatments were observed at peroxone (1:1) 20+30 (i.e., 20 mg/L H2O2: 30 mg/L O3) and 30 mg/L ozone (i.e., reaction rate constant of 0.236 min-1 and 0.251 min-1, respectively). The increase of the DBE increased the reaction rate constant, specifically at DBE = 7-9 with similar values at DBE =3-6. With respect to in vitro assays, while the highest production of nitrite (i.e., attributed as the lowest toxicity effects on the goldfish primary kidney macrophages) was observed in peroxone (1:2) 11+30 (i.e., 11 mg/L H2O2: 30 mg/L O3) followed by peroxone (1:3) 10+50 (i.e., 10 mg/L H2O2: 50 mg/L O3), their O2-NA degradation was the lowest, 47% and 61%, respectively. The residual toxic effects after different ozone and peroxone processes, suggest that part of OSPW toxicity may be caused by specific compounds of NAs (i.e., similar reduction (50%) was achieved in both toxicity and abundance in O2 species with carbon 15-26) and/or generated by-products (e.g., O3S classes at DBE = 4 and C9H12O2 at DBE = 4). Although by-products were generated, slight enhancement in the biodegradability and the reduction of chemical oxygen demand was achieved in peroxone at 1:2 ratio compared to ozone, suggesting the possibility of using combined OSPW remediation approaches (i.e., peroxone coupled with biological process).

Non-point source (NPS) contamination is a major concern for urban aquatic environments. This study tested the feasibility of using slow-release oxidants (SR-O) emplaced in storm pipes for treating organic pollutants in urban storm runoff through proof-of-concept laboratory tests and preliminary field investigations in Athens, OH. Release rates of slow-release persulfate (SR-PS), slow-release hydrogen peroxide (SR-HP), and slow-release hydroxide (SR-OH) were estimated through column tests. Results from column tests show that stable release was achieved after 100 hours of testing. Stable release for SR-HP, SR-SP, and SR-OH were up to 2.8x10-3, 5x10-1, and 2.8x10-1 mg min-1, respectively. SR-PS forms were observed to release for two weeks and at 90-100% efficiency. Total organic carbon, chloride, and sulfate concentrations in a two hour storm ranged from 9.8 to 63.4 mg L-1, 6.7 to 23.4 mg L-1, and 6.0 to 59.0 mg L-1, respectively with maximum concentrations shown in the first flush period. Since no organic pollutants were detected in the storm water, pollutant standard solutions were added to storm water samples to evaluate removal efficiencies of base activated SR-PS systems. Base activated persulfate using SR-PS, SR-HP, and SR-OH was found to be the most efficient system in treating organic pollutants within 30 minutes, the estimated residence time of storm water within storm pipes. The proof-of-concept flow-through test demonstrated that up to 60% of pollutants can be removed by the SR-PS/HP/OH within 30 minutes of reaction time in deionized water and between 25-65%, 13-36% less efficient, in storm water. Estimated Cost of using SR-O systems in urban areas can range between 109 (for 168 two hour storms) and 9908 dollars (for 168 two hour storms) per year depending on area and storm frequencies. These results suggest that installation of SR-PS/HP/OH in storm pipes could provide a novel cost effective treatment scheme for organic pollutants in urban runoff.

Chemical contaminants occurring naturally or derived from human-related activities in sources of drinking water have been associated with a wide array of adverse human and ecological health effects. Global climate change, eutrophication and rampant use of pharmaceuticals will likely exacerbate contamination of sources of drinking water. Alternative sustainable approaches such as advanced oxidation processes (AOPs) are desirable for the production of safe drinking water. In this dissertation, the degradation and structural transformations of cyanobacterial toxins (microcystins and cylindrospermopsin) and antibiotics (ampicillin, penicillin VK, piperacillin and cephalothin) were investigated by hydroxyl and sulfate radicals generated by UV-254 nm AOPs.Tap water and natural water samples from East Fork Lake and Toledo Water Plant in Ohio, Lake Erie in Michigan and St. Johns River in Florida, as well as samples from different water treatment stages from a drinking water treatment plant were used as water matrices to evaluate the application of the AOPs. A final concentration of microcystin-LR (MC-LR) below the safe guideline value of 1 µg L?1 was achievable by UV/H2O2 with 80 mJ cm?2 of UV fluence and 882 µM [H2O2]0 when common radical scavengers such as alkalinity and natural organic matter (NOM) were present. The UV/HSO5? treatment efficiency of cylindrospermopsin (CYN) was enhanced in tap water in the presence of trace transition metals, suggesting that the transition metals in natural waters could be important for the effectiveness of the AOPs. Hydroxylation appeared to be the main reaction pathway during the hydroxyl radical reaction with CYN. The oxidation of secondary alcohol, the formation of a double bond in a conjugation with guanidine group, the cleavage of uracil moiety, as well as the elimination of sulfate group were also observed. Steady-state radical concentrations were estimated revealing a non-negligible contribution of hydroxyl radical in UV/S2O82-. The tert-butyl alcohol (a hydroxyl radical scavenger) was thus added in UV/S2O82-, yielding byproducts that indicated specific sites in CYN preferentially attacked by sulfate radicals (SRs). The selective nature of SR species produced a number of byproducts different from those of hydroxyl radical, although both radical species share similarities in the intermediate radical species. Various byproducts were identified in UV/H2O2 process. Both isomerization and photohydration byproducts were observed in UV only process for all the four MCs (i.e., MC-LR, MC-RR, MC-YR and MC-LA); while in UV/H2O2, hydroxylation, hydroxyl addition and diene-Adda double bond cleavage byproducts were detected. The presence of a tyrosine in MC-YR significantly promoted the formation of monohydroxylation byproduct m/z 1061. It was suggested that the difference in the amino acid variables of MCs influenced not only the degradation kinetics but also the reaction mechanisms. The selected antibiotics (i.e., ampicillin, penicillin, piperacillin and cephalothin) were successfully degraded by UV/H2O2 and UV/S2O82- AOPs, though with a slower formation of sulfate anion in UV/H2O2 and a much slower reduction in total organic carbon contents. The transformation mechanisms were also investigated showing the destruction of the ß-lactam ring with a potential subsequent decrease of the antibiotic activity of the treated waters.

The study aims to develop a novel in situ chemical oxidation scheme which combines controlled-release system (CRS) and advanced oxidation processes (AOPs) for onsite treatment of hydrocarbons in urban runoff. Controlled-release hydrogen peroxide (CR-HP), sodium persulfate (CR-SP), and Fe2+ (CR-Fe) were manufactured by dispersing specific salts in paraffin wax matrices. Degradation efficiencies of BTEX, MTBE, and naphthalene, which are common gasoline compounds found in urban runoff, were investigated through a series of batch tests. Release rates of CR-HP, CR-SP, and CR-Fe were investigated through a series of column tests. The remedial efficiencies of this novel CR-AOPs system was evaluated by flow-through tests. The results showed that this system can degrade ~20% of MTBE, over 80% of BTEX, and over 90% of naphthalene within 3 min of reaction time.

The decomposition of hydrogen peroxide (H2O2) on iron minerals can generate hydroxyl radical (*OH), a strong oxidant capable of transforming a wide range of contaminants. This reaction is critical to ex situ advanced oxidation processes employed in waste treatment systems, as well as in situ chemical oxidation processes used for soil and groundwater remediation. Unfortunately, the process in the ex situ treatment systems is relatively inefficient at circumneutral pH values. In this research, the development of iron-containing catalysts with improved efficiency was investigated. In addition, little is known about the factors that control the performance of in situ treatment systems. Another aim of this dissertation was to elucidate those factors to provide a basis for improving the efficiency of the remediation method. Two types of silica- and alumina-containing iron (hydr)oxide catalysts were synthesized by sol-gel processing techniques (Chapter 2). Relative to iron oxides, such as hematite and goethite, these catalysts were 10 to 80 times more effective in catalyzing the production of *OH from H2O2 under circumneutral conditions. The higher efficiency makes these catalysts promising candidates for ex situ advanced oxidation processes. Moreover, because alumina and silica alter the reactivity of the iron oxides with H2O2, understanding the activity of iron associated with natural aluminosilicates and silica-containing minerals in the subsurface is crucial to explaining the variability of *OH production observed in in situ treatment systems. In addition to the sol-gel technique used in Chapter 2, silica-containing iron (hydr)oxide catalysts were synthesized by immobilizing iron oxide onto mesoporous silica supports, such as SBA-15 (Chapter 5). The iron-containing SBA-15 was 10 times more effective than iron oxides in catalyzing the production of *OH from H2O2. Moreover, this catalyst could be employed for selective oxidation of small organic contaminants based on size exclusion. However, a major drawback of the mesoporous silica-based catalysts is their instability under circumneutral conditions (Chapter 6). The dissolution of mesoporous silica materials raises questions about their use for water treatment, because silica dissolution might compromise the behavior of the material. To gain insight into factors that control H2O2 persistence and *OH yield in in situ processes, the decomposition of H2O2 and transformation of contaminants were investigated in the presence of iron-containing minerals and aquifer materials (Chapter 3). Consistent with the observation described in Chapter 2, iron-containing aluminosilicates were more effective than iron oxides in converting H2O2 into *OH. In both iron-containing mineral and aquifer material systems, the yield of *OH was inversely correlated with the rate of H2O2 decomposition. In the aquifer material systems, the yield also inversely correlated with the Mn content, consistent with the fact that the decomposition of H2O2 on manganese oxides does not produce *OH. The inverse correlation between Mn content and H2O2 loss rate and *OH yield suggests that the amount of Mn in aquifer materials could serve as a proxy for predicting H2O2 decomposition rates and contaminant oxidation efficiency. In addition to the surface and structure properties of iron solids, the presence of solutes, such as dissolved silica, also affected the decomposition of H2O2 (Chapter 4). The adsorption of dissolved silica onto mineral surfaces altered the catalytic sites, thereby decreasing the reactivity of iron- and manganese-containing minerals with H2O2. Therefore, the presence of dissolved SiO2 could lead to greater persistence of H2O2 in groundwater, which should be considered in the design of in situ H2O2-based treatment systems. In addition to in situ treatment, dissolved silica also can affect the reactivity of iron-containing catalysts used in ex situ processes. Therefore, its presence in contaminated industrial wastewater should be considered when ex situ treatment systems are designed.

Natural organic matter (NOM) occurs ubiquitously in drinking water supplies and is problematic since it serves as a precursor to disinfection by-products (DBPs) formation. Stricter DBP regulations will drive utilities to consider advanced treatment processes for DBP control through NOM removal. Herein, the transformation of NOM in homogeneous (UVA/H2O2 and UVA/Fe/H2O2) and heterogeneous (UVA/TiO2) Advanced Oxidation Processes (AOPs) were studied. Organic matter from three different sources was investigated in this work, specifically a commercial humic acid, and two Australian surface water sources. The transformation of the organic matter as a result of oxidation was investigated through multiple analytical techniques, such as UV-Vis spectroscopy, DOC analysis, high performance size exclusion chromatography (HPSEC), resin fractionation, liquid chromatography with organic carbon detection (LC-OCD) and disinfection byproducts formation potential. The multi-analysis approach is required due to the complex and heterogeneous nature of NOM. Each analytical technique provides complementary information on different properties of NOM, leading to a comprehensive understanding on how AOPs transform the chemical and physical properties of NOM. Both homogeneous and heterogeneous AOPs were found to be effective for NOM removal. However, complete mineralisation was not achieved, even under prolonged irradiation. Large aromatic and hydrophobic organics were degraded into lower molecular weight hydrophilic compounds, which had weak UV absorbance at 254 nm. In the UVA/TiO2 treatment, multi-wavelength HPSEC analysis demonstrated the formation of low molecular weight compounds with strong absorbance at wavelength lower than 230 nm. These residual organic compounds, though recalcitrant, had a low reactivity to chlorine to form THMs, and were identified to be low molecular weight acids and neutral compounds from LC-OCD analysis. Finally, the current work reports the novel synthesis of magnetic photocatalyst for NOM oxidation from low cost precursors to solve the separation problem of nano-sized particles. Magnetite particles were coated with a layer of protective silica from sodium silicate precursor. Photoactive titanium dioxide was then deposited onto the silica coated particles using titanium tetrachloride precursor. The as-prepared magnetic photocatalyst exhibited excellent stability and durability. Although the photoactivity of the magnetic photocatalyst is lower than commercial TiO2 photocatalyst, it can be easily recovered by magnetic field.