Scholarship & Research
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Item Evaluation of a constructed wetland : sediment characterization and laboratory simulation of wetland chemical processes(Montana State University - Bozeman, College of Agriculture, 1998) Lyons, Dale WellerItem Remediation of acid rock drainage through the use of a constructed passive treatment system which simulates natural processes(Montana State University - Bozeman, College of Agriculture, 1997) Schmidt, T.G.Item Seasonal plant effects on wastewater treatment and root-zone oxidation in model wetlands(Montana State University - Bozeman, College of Agriculture, 1999) Allen, Winthrop CoffinItem Nutrient assimilation and root porosity responses of aquatic macrophytes to application of dairy effluents using constructed wetlands(Montana State University - Bozeman, College of Agriculture, 1993) Romig, Bryce ReedItem Selecting plant species to optimize wastewater treatment in constructed wetlands(Montana State University - Bozeman, College of Agriculture, 2009) Taylor, Carrie Renee; Chairperson, Graduate Committee: Catherine A. Zabinski.Constructed wetlands are used around the world for treating domestic, agricultural, and industrial wastewater, stormwater runoff, and acid mine drainage. Plants may affect efficacy of wastewater treatment through their influence on microbial activity by creating attachment sites and releasing carbon exudates and oxygen. My research investigated seasonal plant effects on wastewater treatment by monitoring water chemistry in model subsurface wetlands planted with monocultures of 19 plant species and unplanted controls. Chemical oxygen demand (COD) removal, an indicator of water quality, declined during colder temperatures in the unplanted control, likely caused by a decrease in microbial activity. In contrast, wetlands with most plant species had constant COD removal across seasons. Redox potential and sulfate concentrations were measured as indirect measurements of the oxygenation of the wastewater. Wetlands that had a decline in COD removal during cold temperatures had constant low redox potential and sulfate concentrations throughout the seasons. Wetlands with high COD removal across seasons had elevated redox potentials and sulfate concentrations during the winter, indicating elevated oxygen availability, which may offset the negative temperature effect on microbial processes. I measured root oxygen loss (ROL) in the summer and the winter to determine whether oxygen release was sufficient to influence wastewater treatment and cause seasonal and species-specific effects on water chemistry. COD removal and ROL were positively correlated at 4°C but not at 24°C; however, the amount of root oxygen release only accounted for a portion of the required oxygen to facilitate plant's influence on COD removal. Flooding tolerance was quantified for each species by comparing plants' biomass between flooded and drained conditions. Plants' botanical grouping, Wetland Indicator Status, and flooding tolerance were compared to plants' influences on wastewater treatment to determine whether easily measured plant traits can be used to identify plants that will optimize wastewater treatment. All the sedges and rushes, obligate wetlands species, and 8 of 9 flood-tolerant plants had greater COD removal than the control at 4°C, the coldest temperature incubation. These results can be applied for wetland design by selecting plant species to optimize wastewater treatment, especially in cold climates.Item Assessing constructed wetlands for beneficial use of saline-sodic water(Montana State University - Bozeman, College of Agriculture, 2005) Kirkpatrick, Amber Denise; Chairperson, Graduate Committee: James W. Bauder.Changes in agricultural practices, and irrigation strategies combined with natural processes, have led to increased salinization of soil and water resources worldwide. Coal bed methane (CBM) development in the Powder River Basin of Montana and Wyoming results in the co-production of large volumes of sodic and moderately saline discharge water, and represents a potential source of salinization of soil and water resources. The objective of this study was to evaluate the potential of constructed wetlands as a tool for CBM product water management. This was accomplished by assessing seasonal water use, biomass production and water use efficiencies (WUE) of three plant communities. Native species establish hydrologically distinct communities in former ephemeral channels now running with CBM product water, and nine species of those cataloged were selected and segregated into three communities. Closed-system wetland cells were constructed and each community was assigned to four of these cells, i.e., lysimeters. Chemistry of the supply water was sodic and moderately saline (EC ~ 3.4 dS/m, SAR > 25), typical of northern portions of the Powder River Basin where low to moderate electrical conductivities (EC 2-3 dS/m) and high sodium adsorption ratios (SAR > 20) are common. All three communities had similar total water use but WUE's differed significantly among the communities. Evaporation from a Class A evaporation pan was observed to be higher than evapotranspiration from the planted lysimeters, but this is not definitive as there was only one replication of the pan. Species survival and colonization was very good for seven of the nine species selected. American bulrush (Scirpus americanus) had very sparse spring regrowth and Inland saltgrass (Distichlis stricta) was likely out-competed by Creeping spikerush (Eleocharis palustris). Results of this study indicate that constructed wetlands planted with native, salt tolerant species have potential to utilize substantial volumes of CBM product water while remaining robust and viable. Although results suggest evaporation from an open water surface to be greater than evapotranspiration from a constructed wetland, constructed wetlands have added benefits of providing wildlife habitat, recreation and viewshed enhancement.