AuthorWard, William Jackson
AdvisorQuanrud, David M.
Committee ChairQuanrud, David M.
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.
AbstractThis research addressed the question whether a constructed wetland system with phytoremediation could successfully uptake 1,4-Dioxane in groundwater and secondary effluent. It further addressed whether open pond storage could successfully treat wetland discharge. The project was located at the University of Arizona's Constructed Ecosystems Research Facility (CERF) in Tucson, Arizona. This two-year field study was motivated by previous laboratory studies which demonstrated the capability of plants to remediate the recalcitrant contaminant 1,4-Dioxane.The study was conducted in two open steel tanks configured to simulate constructed wetlands. The efficacy of 1,4-Dioxane uptake by cottonwood trees was tested in a side-by-side comparison utilizing planted and unplanted tanks. The sub-surface hydraulic conditions were fully characterized by bromide tracer studies. Six experiments were conducted, in which tapwater or secondary effluent was spiked with 5.2 mg/L 1,4-Dioxane and fed to the planted and unplanted (control) tank. The tank discharges were retained in separate open ponds to test if open pond storage would reduce 1,4-Dioxane content. Additional side experiments were conducted to examine the role of volatilization and UV degradation. Comparison of 1,4-Dioxane mass discharge from the planted and the control tank demonstrated an 18-48 percent uptake by the cottonwood trees. Mass balance assessments showed 1,4-Dioxane uptake efficiency was positively correlated to cottonwood transpiration rates in the planted tank. The open pond 1,4-Dioxane measurements demonstrated a 64-85 percent reduction in 1,4-Dioxane concentration due to volatilization during the initial 120 hours pond lapse time. Elimination of 1,4-Dioxane from the ponds followed first order kinetics. Field and laboratory side experiments demonstrated the potential for UV photo degradation of 1-4-Dioxane.
Degree ProgramArid Lands Resource Sciences