Many soil and aquifer systems in the United States have been subjected to chemical contamination from past industrial and military activities. While many remediation technologies are currently being applied, in situ chemical oxidation (ISCO) is one option that is often favored because of its potential for fast remediation times and high user control. This technology involves the direct injection of chemical oxidizers (e.g. hydrogen peroxide, ozone, or permanganate) into targeted contaminant zones within the subsurface, and it has been proven to be amenable to both BTEX compounds and other volatile organic compounds such as chlorinated solvents. This study had several key objectives. Firstly, multiple soil samples, each containing an elevated level of a targeted chemical constituent, were successfully collected in order to provide a wide range of soil types in order to make important comparisons and correlations related to ISCO?s impacts. Secondly, the impact of common soil constituents on process reagent transport was studied in order to determine which soil constituents would act as primary hindrances for the transport of hydrogen peroxide and ozone into the subsurface. Thirdly, experiments were performed to pinpoint certain personnel safety threats such as excess oxygen and heat generation that might arise during process application. Fourthly, the impact of ISCO process application on soil fabric properties was examined. Soil aerobic microbial populations, soil hydraulic conductivity, soil natural organic matter constituents, and soil adsorptive properties were all shown to be impacted following the application of chemical oxidizers.

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Advanced water treatment (AWT)/reuse has become a necessity for many utilities across the globe as the quantity and quality of water resources has been diminished. In some locations including California, the full-advanced treatment (FAT) train is mandated including membrane filtration, reverse osmosis, and UV advanced oxidation. The application of carbon-based treatment has emerged as a cost-effective alternative to FAT in locations that cannot manage brine disposal. However, considering the relative novelty of this treatment technology for water reuse, the process still requires full-scale validation of treatment goals including pathogen reduction. While there are many constituents of concern in water reuse, exposure to pathogens remains the greatest acute health risk. The studies described herein examine pathogen and microbial surrogate reduction both full-scale and pilot-scale floc/sed-ozone-biofiltration advanced water treatment facility. Both culture and molecular-based methods were used to demonstrate removal in this case and pilot challenge testing was employed to address the shortcomings of full-scale monitoring and to address additional research objectives. The reduction of Cryptosporidum, Giardia, enteric viruses, pathogenic bacteria and their corresponding surrogate microorganisms (e.g. spore forming bacteria, coliphage) was quantified across the upstream wastewater treatment process and the AWT. In general, the removal of surrogate microorganisms was less than or equal that of the pathogens of interest thereby justifying their use in full-scale monitoring. Several limitations of full-scale monitoring were noted including low starting concentrations which resulted in large sample volume required to demonstrate log-reduction. Additionally, while molecular methods were sufficient to demonstrate reduction by physical treatment steps, they are unable to demonstrate inactivation. Therefore, ozone pilot testing was performed to evaluate the use of capsid integrity PCR for showing inactivation by ozonation. Additional testing was also performed to relate the LRV shown with culture methods to the LRV shown with PCR so as to create a relationship that can be used in future monitoring. While pathogen inactivation is a major concern in water reuse, these objectives must also be balanced with the formation of disinfection byproducts (DBPs) through ozonation. Given the elevated concentration of dissolved organic matter, relatively higher ozone doses are required in reuse applications when compared with water treatment applications in order to achieve the desired treatment goals (oxidation, disinfection). Pilot scale ozone testing was performed to evaluate ozone disinfection performance in unfiltered secondary effluent while balancing the formation of bromate and oxidation of trace organic contaminants (TrOCs). Two chemical bromate control methods were compared including preformed monochloramine (NH2Cl), and hydrogen peroxide (H2O2). Neither of these bromate control methods had any demonstrable impact on virus or coliform inactivation, however H2O2 eliminated measurable ozone exposure which is necessary for the inactivation of more resistant spore forming bacteria. Additionally, NH2Cl was shown to suppress *OH exposure and thus negatively impacted the oxidation of ozone resistant TrOCs, while H2O2 marginally improved TrOC oxidation. Finally, the use of H2O2 for bromate control necessitates the validation of an alternative framework for ozone process control. The existing ozone Ct framework has been shown to be prohibitively conservative especially for virus inactivation. In this study, the applied specific ozone dose (O3:TOC) and the change in UV254 absorbance were evaluated as ozone monitoring frameworks across a range of water quality characteristics. Elevated temperature and pH were shown to significantly impact ozone decay kinetics, and only marginally impact virus inactivation. Both frameworks that were evaluated were shown to be valid across all water quality conditions evaluated. Validating pathogen reduction across carbon-based reuse treatment trains is imperative in order to allow for more widespread application and regulatory confidence in the technology. Coagulation, floc/sed, ozone, and biofiltration were shown to be robust barriers for pathogen and surrogate reduction and recommended concentration and quantification methods are presented herein. The ozone challenge testing results also provide guidance to utilities using ozone for disinfection while controlling DBPs and enhancing organics oxidation in water reuse applications. / Doctor of Philosophy / Water reuse has become a necessity for many utilities across the globe as the quantity and quality of water resources has been diminished. In some locations including California, the full-advanced treatment (FAT) train is required including membrane filtration, reverse osmosis, and UV advanced oxidation. The application of carbon-based treatment has emerged as a cost-effective alternative to FAT in locations that cannot manage brine disposal. However, considering the relative novelty of this treatment technology for water reuse, the process still requires full-scale validation of treatment goals including pathogen reduction. While there are many constituents of concern in water reuse, exposure to pathogens remains the greatest acute health risk. The studies described herein examine pathogen and microbial surrogate reduction both full-scale and pilot-scale floc/sed-ozone-biofiltration advanced water treatment facility. Both culture and molecular-based methods were used to demonstrate removal in this case and pilot challenge testing was employed to address the shortcomings of full-scale monitoring and to address additional research objectives. The reduction of protozoa, viruses, bacteria and their corresponding surrogate microorganisms was quantified across the upstream wastewater treatment process and the water reuse treatment train. In general, the removal of surrogate microorganisms was less than or equal that of the pathogens of interest thereby justifying their use in full-scale monitoring. Several limitations of full-scale monitoring were noted including low starting concentrations which resulted in large sample volume required to demonstrate log-reduction. Additionally, while molecular methods were sufficient to demonstrate reduction by physical treatment steps, they are unable to demonstrate inactivation. Therefore, ozone pilot testing was performed to evaluate several methods to adapt these methods to reflect inactivation. While pathogen inactivation is a major concern in water reuse, these objectives must also be balanced with the formation of disinfection byproducts through ozonation. Given the elevated concentration of dissolved organic matter, relatively higher ozone doses are required in reuse applications when compared with water treatment applications in order to achieve the desired treatment goals (oxidation, disinfection). Pilot scale ozone testing was performed to evaluate ozone disinfection performance in wastewater effluent while balancing the formation of byproducts and oxidation of trace organic contaminants. Two chemical byproduct control methods were compared including preformed monochloramine, and hydrogen peroxide. Neither of these bromate control methods had any demonstrable impact on virus or coliform inactivation, however H2O2 eliminated measurable ozone exposure which is necessary for the inactivation of more resistant spore forming bacteria. Additionally, monochloramine was shown to suppress hydroxyl radical exposure and thus negatively impacted the oxidation of ozone resistant organic contaminants, while hydrogen peroxide marginally improved oxidation. Finally, the use of hydrogen peroxide for bromate control necessitates the validation of an alternative framework for ozone process control. The existing framework that relies on ozone exposure has been shown to be conservative especially for virus inactivation. In this study, the applied specific ozone dose and the change in UV254 absorbance were evaluated as ozone monitoring frameworks across a range of water quality characteristics. Elevated temperature and pH were shown to impact ozone decay kinetics and virus inactivation to varying degrees. Both frameworks that were evaluated were shown to be valid across all water quality conditions evaluated. Validating pathogen reduction across carbon-based reuse treatment trains is imperative in order to allow for more widespread application and regulatory confidence in the technology. Coagulation, flocculation/sedimentation, ozone, and biofiltration were shown to be robust barriers for pathogen and surrogate reduction and recommended concentration and quantification methods are presented herein. The ozone challenge testing results also provide guidance to utilities using ozone for disinfection while controlling disinfection byproducts and enhancing organics oxidation in water reuse applications.

Acquiring in depth knowledge of the ozone oxidation of surface-bound fullerenes advances the understanding of fullerene fate in the environment, as well as the reactivity of ozone with carbonaceous nanomaterials. Recent ultrahigh vacuum studies of the reaction of gasphase ozone with surface-bound fullerenes have made it possible to observe the formation and subsequent thermal decomposition of the primary ozonide (PO). As the use of nanomaterials, such as C₆₀, continues to increase, the exposure of these molecules to humans and the environment is of growing concern, especially if they can be chemically altered by common pollutants. These experiments are made possible by combining ultrahigh vacuum surface analysis techniques with precision dosing using a pure O₃ gas source. The experimental setup also provides the capability of monitoring surface-bound reactants and products in situ with reflection-absorption IR spectroscopy, while gas-phase products are detected with a mass spectrometer. Our results indicate that ozone adds across a 6/6 bond on the C₆₀ cage, forming an unstable intermediate, the primary ozonide. The observed initial reaction probability for the PO is γ = 4.1 x 10⁻³. Energies of activation for the formation and decomposition of the PO were obtained via temperature-dependent studies. After formation, the primary ozonide thermally decomposes into the Criegee Intermediate which can rearrange or, upon further exposure to ozone, react with another ozone molecule to form a variety of products such as carbonyls, anhydrides, esters, ethers, and ketenes. Larger fullerenes (C₇₀, C₇₆, C₇₈, and C₈₄) were also exposed to gas-phase ozone, in order to observe the reaction rate for ozonolysis and to propose an initial mechanism for ozone exposure. The results indicate that the structure of the fullerenes has little to no impact on the rate of oxidation via ozone. Lastly, Terbium endohedral were exposed to ozone, in an effort to determine whether ozone was capable of oxidizing both the outer fullerene cage, as well as the Tb atom sequestered inside. The preliminary XPS data suggests ozone oxidizes both within an hour of continuous exposure. Understanding this atmospherically-relevant reaction from both a mechanistic and kinetic standpoint will help predict the environmental fate of fullerenes and their oxides. / Ph. D.

Ozone generation is a problem associated with indoor air cleaners that utilize a corona to ionize particles. This experimentation utilized a negative corona and investigated the effect that external electrode wire heating had on the ozone production rate. Results showed that the ozone generation rate could be significantly reduced by raising the electrode surface temperature to 85 °C. Above this temperature, no further ozone reduction was observed. A linear relationship existed between ozone concentration and corona current. A parabolic relationship existed between corona current and corona voltage potential. Smaller corona wire diameters produced ozone at lower rates than larger corona wire diameters. A description of the investigation, the data collected, and a discussion of all results is included. / Master of Science