UV disinfection of drinking water is becoming more common as water utilities attempt to control the formation of disinfection byproducts. While most organisms are readily inactivated by UV, certain viruses require a large fluence for adequate disinfection. In this study, photocatalytic silver doped titanium dioxide nanoparticles were investigated for their capability to enhance the UV disinfection of Bacteriophage MS2. The inactivation kinetics were compared to the base TiO2 material and silver nanoparticles. Inactivation of MS2 was enhanced by doping TiO2 with 8 and 10 wt. % silver, while no enhancement was observed with 4 and 6 wt. % silver. In order to determine the inactivation mechanism, alcohol scavengers were employed to eliminate the effects of hydroxyl free radical. When nAg/TiO2 was used as the catalyst, the alcohols significantly decreased the inactivation rate, but did not completely eliminate the virucidal activity. When P25 TiO 2 was used, no virus inactivation was observed.

The more wide-spread use of nanofiltration membranes in industrial applications is dependent upon understanding the fouling behavior of representative feed solutions, such as complex suspensions with both organic and colloidal inorganic foulants. In this thesis, three hypothesized mechanisms responsible for enhanced membrane flux decline in the presence of multiple foulant types are examined experimentally: increased hydraulic resistance of the mixed cake layer structure, hindered foulant diffusion due to interactions between solute concentration polarization (CP) layers, and changes in colloid surface properties due to organic adsorption. Additionally, a modified composite cell-model is developed to incorporate the structural differences of a merged, combined fouling layer. Results, including a synergistic effect caused by increased resistance of a heterogeneous fouling layer as well as the adsorption effects of interacting foulants, indicate that current fouling layer models need to be reexamined to include the mechanisms suggested in this study.

The U.S. EPA recommends adding of 5-25mg/L ferric salt to remove arsenate (V) at pH 5 to 8 in water treatment plants. Citrate has been proven to inhibit ferric hydroxide floc formation and corresponding arsenic adsorption. Although most research has been conducted at high molar ratios of citrate to iron, low molar ratios were used in this work and the inhibition of floc formation remained constant above a molar ratio of 0.05. Nucleation kinetics of ferric hydroxides and arsenic removal was investigated in the presence of citrate at low molar ratios (citrate/Fe ranging from 0 to 0.28). At concentrations found in natural waters (4.5-25muM), citrate effectively inhibited ferric hydroxide nucleation and precipitation by forming a non-crystalline macromolecular complex (FeO(Fe3O12H3)Cit) detected in aqueous phase by electrospray ionization mass spectrometry (ESI-MS). Arsenate removal by nano magnetite was also retarded by a low concentration of citrate. The effectiveness of citrate was more significant at higher pH values. Possible mechanisms of citrate inhibition at low molar ratios were compared and discussed. This research demonstrated that the citrate impact upon arsenate removal should be considered when using the iron coagulation and precipitation method in water treatment plants.

1,4-Dioxane is an emerging groundwater contaminant and a probable human carcinogen. Its biodegradation was investigated in microcosms prepared with groundwater and soil from an impacted site in Alaska. In addition to natural attenuation conditions (i.e., no amendments), the following treatments were tested: (a) biostimulation by addition of 1-butanol (a readily available auxiliary substrate) and inorganic nutrients; and (b) bioaugmentation with Pseudonocardia dioxanivorans CB1190, a well-characterized dioxane degrading bacterium, or with Pseudonocardia antarctica DVS 5a1, a bacterium isolated from Antarctica. Biostimulation enhanced the degradation of 50 mg L-1 dioxane by indigenous microorganisms (about 0.01 mg dioxane d-1 mg protein-1) at both 4 and 14°C, with a simultaneous increase in biomass. A more pronounced enhancement was observed through bioaugmentation. Microcosms with 50 mg L -1 initial dioxane (representing source zone contamination) and augmented with CB1190 degraded dioxane fastest (0.155 +/- 0.038 mg dioxane d-1 mg protein-1) at 14°C, and the degradation rate decreased dramatically at 4°C (0.021 +/- 0.007 mg dioxane d-1 mg protein-1). In contrast, microcosms with DVS 5a1 degraded dioxane at similar rates at 4 and 14°C (0.018 +/- 0.004 and 0.015 +/- 0.006 mg dioxane d-1 mg protein-1, respectively). DVS 5a1 outperformed CB1190 when the initial dioxane concentration was low (500 microg L-1). This indicates differences in competitive advantages of these two strains. Natural attenuation microcosms also showed significant degradation over 6 months when the initial dioxane concentration was 500 microg L-1. This is the first study to report the potential for dioxane bioremediation and natural attenuation of contaminated groundwater in sensitive cold-weather ecosystems such as the Arctic.

The Yuna River watershed experiences long-duration floods near its mouth, and deadly flash floods in its mountainous upper reaches. To better understand this watershed, a distributed hydrologic model is created that describes flood behavior and acts as a resource for flood control decisions. Since gage and hydrologic data in the watershed is sparse, the model requires customized calibration to historic storms. Using the calibrated model outputs, a GIS-based Area-Slope statistic is proposed that prioritizes tributaries for flood control and permits implementation of parallel modeling in nearby watersheds. Additionally, a flood alert tool is proposed that catalogues expected peak flows, times to peak, and time delays around the city of Bonao. Potential structural controls are tested for effective flow attenuation, including reservoirs and diversions. The flood control analysis indicates that a multiple structure approach and/or a non-structural approach is necessary in Bonao, where a number of topographic factors exacerbate flooding.

With increased attention on rising carbon dioxide levels, carbon capture and sequestration (CCS) has become a commonly proposed solution. CCS has been studied for several decades, but is being researched more and more seriously as to whether it may be a viable and economically feasible long-term solution to climate change. Research conducted for this project is for application at the site of a coal fired power facility in the Black Warrior Basin of Alabama, and was funded by the DOE Recovery Act. Despite the excitement regarding CCS, some major technical obstacles exist due to the nature of working with acidic solutions and carbonate formations. This project explores the dissolution of carbonate formations while exposed to an acidic brine solution. Dissolution kinetics, with and without inhibitors, are presented and compared with modeled expectations.

Utilizing a randomized phone survey of coastal Louisiana residents, this study will focus on identifying which influences from a residents exposure, socio-economic vulnerability and adaptive capacity are the best indicators of an individuals resilience. Two binary logistic regression models were developed to test the associations of resident response to: 1) acute hazards via household emergency plan adoption and 2) chronic hazards represented by behavior modification in response to daily air quality reporting where adoption of these two risk-reducing behaviors are viewed as increased individual resilience. Bivariate correlation analysis found that a north south grouping of coastal Louisiana was significantly correlated with 26 of the survey predictor variables. The two binary logistic regression model results include: as an individuals current level of environmental hazard knowledge increases by 1-increment they are 53% more likely to engage in the risk-reducing behavior, adoption of an emergency plan and almost 5 in 10 residents of the southern region reported altering their behavior on poor air quality days. This self-reported mitigation effort is associated with an increase in their personal level of concern for overall environmental pollution. Overall the results indicate when residents are provided with relevant environmental hazard information and, more importantly, when residents understand and have confidence in the hazard information, they are more likely to take anticipatory and pre-emptive measures to reduce their risk. While this study found less optimal risk-reducing adoption rates, the finding suggests immediate opportunities for government agencies and public-interest organizations to increase public education efforts to target audiences who are willing and receptive to increased environmental hazard information. Future research improvements should include increased survey questions, new survey administering methods, broadening the geographical scope of the research project, and, thus, increasing the sampling population size.

The Lewiss Woodpecker (Melanerpes lewis) is known to breed in ponderosa pine, cottonwood riparian, aspen, and burned conifer forest types, but is declining in much of its range throughout the U.S. and is listed as a Level II Species of Concern in Montana. In western Montana, Lewiss Woodpeckers commonly breed in riparian bottomlands, but information on characteristics of their preferred nesting habitat within these areas is lacking. I studied nesting habitat use by Lewiss Woodpeckers in two important breeding areas in cottonwood-dominated riparian forest along the Clark Fork and Bitterroot rivers in western Montana. I found 55 nests during the summer of 2012, and measured vegetation characteristics around 38 of those nest sites as well as 30 randomly located sites within the same forests. My main objective was to examine nest-tree, local, and landscape habitat characteristics of Lewiss Woodpeckers at nest sites and random sites to determine whether sites used in western Montana river systems were a nonrandom subset of bottomland conditions and whether used conditions were similar to those reported from other parts of their geographic range. Logistic regression models were developed based on used sites and available sites within the study area. Results showed that Lewiss Woodpeckers used larger snags in areas with relatively high percent shrub cover and relatively high snag density per hectare. Snags provide perches to forage from, cavities for nesting, and an open canopy, while the shrub understory supports arthropod prey. From a landscape perspective, Lewiss Woodpeckers nest sites were closer to agricultural fields than were randomly located sites, suggesting adjacent fields were preferred. Information from this study will be disseminated to land managers and private landowners, recommending desired vegetation conditions to benefit this species, including snag retention. To ensure that conditions suitable for Lewiss Woodpecker are maintained in perpetuity will also require management of the river system in its entirety.

Near-surface contaminant isolation facilities are routinely used for the disposal of hazardous and radioactive waste. The objective of these facilities is to maintain the long-term isolation of the identified contaminants as well as to mitigate their associated hazards. Societys experience with modern isolation techniques is beginning to show that these facilities and associated management techniques do not always perform as expected. This research investigated the potential failure of contaminant isolation facilities. Failure, in the context of this research refers to a contaminant isolation facilitys inability to maintain contaminant isolation. Errors were viewed as potential precursors to future failure as they are an indication that actions did not go according to the plan or that the plan itself was inadequate to achieve the objective. This research used a multiple case study design to further investigate what barriers and controls are used for long-term contaminant isolation and how these controls are currently performing. Seven case study reports were developed as part of this research. The sites investigated included Anaconda, Burrell, Canonsburg, Love Canal, Maxey Flats, Rocky Mountain Arsenal, and Spring Valley. Each of these cases involved sites where persistent contaminants were isolated on-site in the shallow subsurface. A cross-case failure analysis was then performed. Fault trees were developed and are presented in this research to illustrate potential failure pathways for each of the contaminant isolation facility controls. Individual controls were found to contain many single point errors. These controls can be described as non-robust in that one event could potentially lead to a control error. System failure was found to require the breach of an engineered barrier. For engineered barrier error to occur a prior institutional control error must occur. Institutional control error alone does not appear to lead to system failure. Institutional control error, however, could be viewed as precursors to potential system failure. The lack of information management, stakeholder awareness and adequate resources were found to be key initiating events potentially leading to system failure. These initiating events could lead to latent institutional control error, which are not fully realized until subsequent events occur.

Secondary materials such as bottom ash, slag, concrete debris, and other waste materials are being considered for use as substitutes for natural aggregates in highway applications due to suitable engineering and economic properties. This research investigated the effect of freezing and thawing on flow mechanisms and constituent leaching from recycled concrete during a scenario of infiltration. Laboratory flow column tracer and leaching studies coupled with freeze/thaw aging were performed on laboratory formulated concrete. Three material moisture contents including the optimum moisture content of the packed material and three levels of freeze/thaw aging were examined to simulate different extents of freeze/thaw exposure. Variation in flow through the columns was observed between the different levels of freeze/thaw cycling and moisture contents. The columns receiving the maximum number of freeze/thaw cycles demonstrated a lower release of calcium, sodium, potassium, chloride, and sulfate, especially at low LS ratios, which may be due to consolidation of the material during freezing and thawing action. Overall, no significant effect of freeze/thaw cycling was observed in the leaching of trace metals. Results were compared to columns subjected to more rapid freeze/thaw cycling. Additionally, a limited number of intermittent flow columns with F/T aging were run on both laboratory formulated concrete material and actual recycled concrete (construction debris) to simulate field-like conditions.