AuthorSherchan, Samendra Prasad
Soil, Water & Environmental Science
AdvisorPepper, Ian L.
MetadataShow full item record
PublisherThe University of Arizona.
RightsCopyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author.
EmbargoRelease after 20-Aug-2013
AbstractTo protect public health, detection and treatment technologies have been improved to monitor and inactivate pathogens in drinking water. The goal of this dissertation is to evaluate and utilize multiple online sensors and advanced oxidation processes to document both the detection as well as destruction of microbial contaminants in real-time. Reviews of rapid detection technologies for real-time monitoring of pathogens in drinking water and advanced technologies to inactivate pathogens in water are shown in Appendices A and B. The study in Appendix C evaluated the efficacy of real-time sensors for the detection of microbial contaminants. Bacillus thuringiensis was used in this research as a surrogate for Bacillus anthracis to determine each sensor response and detection capability. The minimum threshold responses of sensors were determined by injecting B.thuringiensis into deionized (DI), raw (unfiltered) tap water, or filtered tap water over a concentration range of 10² - 10⁵ spores/ml. The BioSentry sensor responded to increases in concentration over the range of 10² - 10⁵ spores/ml. Below this range, sensors provided signals undistinguishable from background noise. The select sensors can detect microbial water quality changes, and these advanced technologies can be integrated to monitor intrusion events in water distribution systems. The study in Appendix D evaluated the efficiency of the UV reactor for inactivation of MS2 coliphage. The virus MS2 coliphage (ATCC 15597-B1) has been proposed by the U.S. Environmental Protection Agency as a standard for UV reactor validation in the United States. In addition, MS2 is used as a surrogate for enteric viruses due to its similar size and morphology. Following UV radiation at a flow rate of 2gpm, infective MS2 showed a reduction of 5.3- log₁₀ when quantified with cultural plaque counts, whereas corresponding quantitative polymerase chain reaction (qPCR) data showed only a 1.7- log₁₀ reduction in viral RNA copy number. In contrast, plaque assay revealed a 5.8- log₁₀ inactivation; a slight increase in infective MS2 coliphage reduction at 1 gal per min but qPCR results indicate a 2.8- log₁₀ reduction in viral RNA copy number; a one log more inactivation compared to 2 gpm. When H₂O₂ was added at either 2.5 or 5 mg/l with UV at either flow rate, enhanced MS2 inactivation occurred with a greater than 7 log₁₀ reduction observed via plaque counts, indicating that all added MS2 had been inactivated, since no plaques were formed after incubation at 37°C for 24 hours. Correspondingly, qPCR data only showed a 3-4 log₁₀ reduction in viral RNA copy number. The study in Appendix E utilized online sensor to document the destruction of E.coli and Bacillus thuringiensis spores by UV/H₂O₂ treatment. In this study, Escherichia coli was tested for potential UV/H2O2 treatment in DI water and online sensors were also integrated to monitor the destruction in real-time. Pilot-scale experiments were performed using a Trojan UVSwift SC reactor (Trojan Technologies, London, ON, Canada) at a flow rate of 1 gal./min (gpm). UV radiation and UV/H₂O₂ combination in E.coli cell suspensions resulted in a >6 log₁₀ reduction of the viable counts. Similar exposure to B.thuringiensis spores resulted in a 3 log₁₀ reduction in viable counts. Scanning electron microscopy of the treated samples revealed severe damage on the surface of most E.coli cells, yet there was no significant change observed in the morphology of the B. thuringiensis spores. Following UV/H₂O₂ exposure, the BioSentry sensor showed an increase in the unknown, rod and spores counts, and did not correspond well when compared to viable counts assays. Data from this study show that advanced oxidation processes effectively inactivate E. coli vegetative cells, but not B.thuringiensis spores which were more resistant to UV/H₂O₂.
Degree ProgramGraduate College
Soil, Water & Environmental Science
Degree GrantorUniversity of Arizona
Showing items related by title, author, creator and subject.
Flow and water quality relations between surface water and ground water in the Puerco River basin near Chambers, ArizonaNeuman, Shlomo P.; Van Metre, Peter Chapman, 1956- (The University of Arizona., 1990)The Puerco River is an ephemeral stream that received effluent from uranium-mine dewatering operations from the 1950's until 1962 and from 1968 until mining ceased in 1986. Flow and water-quality relations between the Puerco River and the alluvial aquifer underlying it were investigated at a site near Chambers. Data collection included installing and sampling nine monitor wells and two drive points; monitoring stage and sampling surface water; and slug testing wells. The stream recharges the alluvial aquifer during periods of flow and the streambed is a location of ground-water discharge by evapotranspiration during periods of no flow. Discharge by evapotranspiration may exceed recharge thus reducing the potential for contaminant movement away from the river by advective transport. Geochemical modeling indicates that uranium minerals are undersaturated in the range in Eh observed. A +0.84 correlation was calculated relating dissolved uranium concentration to depth in monitor wells suggesting the stream is a source of uranium to the alluvial aquifer. (Abstract shortened with permission of author.)
A GEOCHEMICAL APPROACH TO DETERMINE GROUND-WATER FLOW PATTERNS IN THE SIERRA VISTA BASIN, ARIZONA, WITH SPECIAL EMPHASIS ON GROUND-WATER/SURFACE-WATER INTERACTIONMaddock, Thomas, III; Coes, Alissa L. (The University of Arizona., 1997)Water quality in the Sierra Vista Ground-Water Basin is of extreme importance due to the basin's unique ecosystem and predicted future population growth. Portions of the Upper San Pedro River, flowing through the Sierra Vista Basin, contain some of the few remaining perennial streamflows in the southwest. Baseflow in the perennial reaches of the river are maintained almost entirely by the regional and floodplain aquifer systems. A population increase is predicted for the Sierra Vista Basin, and an impact on groundwater quality and availability can be expected. Due to the closely linked hydrologic systems within the basin, contamination or depletion of the regional aquifer could have direct implications for the San Pedro River. Water samples were collected within the study area from the regional and floodplain aquifers, the San Pedro River, and a bedrock spring in the Huachuca Mountains. Samples were analyzed for field parameters, major-ions, and stable isotopes to describe the main chemical characteristics of the hydrologic systems within the basin. Analysis of regional aquifer geochemistry indicates a ground-water system strongly controlled by calcite precipitation. Specific conductance, deuterium and oxygen-18 values indicate a mixing of regional-aquifer ground water and San Pedro River surface water within the floodplain aquifer. Estimates of inflow to perennial reaches of the floodplain aquifer from the regional aquifer vary from 50 to 80%, depending on location. Inflow to the San Pedro River at Charleston from the regional aquifer is estimated to be about 50 to 70% of the stream discharge.
Modeling of ground-water flow and surface water/ground-water interactions of the San Pedro River Basin, Cochise County, ArizonaMaddock, Thomas, III; Vionnet, Leticia Beatriz (The University of Arizona., 1992)Ground-water exploitation in the Upper San Pedro Basin has produced the formation of a cone of depression around the Sierra Vista-Fort Huachuca area. A portion of the mountain front recharge that otherwise would reach the San Pedro River is being intercepted by pumping, and portions of baseflow are being captured by pumping. The purpose of this study is to construct a simulation model capable of simulating the ground-water system as well as the ground-water-surface water interactions. The flow simulation was done by a three-dimensional, finite-difference ground-water flow model (MODFLOW) that incorporates a new stream-aquifer interaction package. Steady state simulations were performed to represent mean annual conditions. Transient simulations cover a 48 year period, starting in 1940 and ending in 1988. A sensitivity analysis of the steady state model was also performed.