Matching Items (3)
Filtering by
- All Subjects: Groundwater
- All Subjects: Metals--Environmental aspects.
- Genre: Masters Thesis
- Creators: Olson, Larry
- Creators: Bergelin, Paul
- Creators: Cadillo – Quiroz, Hinsby
- Resource Type: Text
Description
The goal of the study was twofold: (i) to investigate the synthesis of hematite-impregnated granular activated carbon (Fe-GAC) by hydrolysis of Fe (III) and (ii) to assess the effectiveness of the fabricated media in removal of arsenic from water. Fe-GAC was synthesized by hydrolysis of Fe(III) salts under two Fe (III) initial dosages (0.5M and 2M) and two hydrolysis periods (24 hrs and 72 hrs). The iron content of the fabricated Fe-GAC media ranged from 0.9% to 4.4% Fe/g of the dry media. Pseudo-equilibrium batch test data at pH = 7.7±0.2 in 1mM NaHCO3 buffered ultrapure water and challenge groundwater representative of the Arizona Mexico border region were fitted to a Freundlich isotherm model. The findings suggested that the arsenic adsorption capacity of the metal (hydr)oxide modified GAC media is primarily controlled by the surface area of the media, while the metal content exhibited lesser effect. The adsorption capacity of the media in the model Mexican groundwater matrix was significantly lower for all adsorbent media. Continuous flow short bed adsorber tests (SBA) demonstrated that the adsorption capacity for arsenic in the challenge groundwater was reduced by a factor of 3 to 4 as a result of the mass transport effects. When compared on metal basis, the iron (hydr)oxide modified media performed comparably well as existing commercial media for treatment of arsenic. On dry mass basis, the fabricated media in this study removed less arsenic than their commercial counterparts because the metal content of the commercial media was significantly higher.
ContributorsJain, Arti (Author) / Hristovski, Kiril (Thesis advisor) / Olson, Larry (Committee member) / Madar, David (Committee member) / Edwards, David (Committee member) / Arizona State University (Publisher)
Created2011
Description
The act of moving water across basins is a recent phenomenon in Arizona water policy. This thesis creates a narrative arc for understanding the long-term issues that set precedents for interbasin water transportation and the immediate causes--namely the passage of the seminal Groundwater Management Act (GMA) in 1980--that motivated Scottsdale, Mesa, and Phoenix to acquire rural farmlands in the mid-1980s with the intent of transporting the underlying groundwater back to their respective service areas in the immediate future. Residents of rural areas were active participants in not only the sales of these farmlands, but also in how municipalities would economically develop these properties in the years to come. Their role made these municipal "water farm" purchases function as exchanges. Fears about the impact of these properties and the water transportation they anticipated on communities-of-origin; the limited nature of economic, fiscal, and hydrologic data at the time; and the rise of private water speculators turned water farms into a major political controversy. The six years it took the legislature to wrestle with the problem at the heart this issue--the value of water to rural communities--were among its most tumultuous. The loss of key lawmakers involved in GMA negotiations, the impeachment of Governor Evan Mecham, and a bribery scandal called AZScam collectively sidetracked negotiations. Even more critical was the absence of a mutual recognition that these water farms posed a problem and the external pressure that had forced all parties involved in earlier groundwater-related negotiations to craft compromise. After cities and speculators failed to force a bill favorable to their interests in 1989, a re-alignment among blocs occurred: cities joined with rural interests to craft legislation that grandfathered in existing urban water farms and limited future water farms to several basins. In exchange, rural interests supported a bill to create a Phoenix-area groundwater replenishment district that enabled cooperative management of water supplies. These two bills, which were jointly signed into law in June 1991, tentatively resolved the water farm issue. The creation of a groundwater replenishment district that has subsidized growth in Maricopa, Pinal, and Pima Counties, the creation water bank to store unused Central Arizona Project water for times of drought, and a host of water conservation measures and water leases enabled by the passage of several tribal water rights settlements have set favorable conditions such that Scottsdale, Mesa, and Phoenix never had any reason to transport any water from their water farms. The legacy of these properties then is that they were the product of the intense urgency and uncertainty in urban planning premised on assumptions of growing populations and complementary, inelastic demand. But even as per capita water consumption has declined throughout the Phoenix-area, continued growth has increased demand, beyond the capacity of available supplies so that there will likely be a new push for rural water farms in the foreseeable future.
ContributorsBergelin, Paul (Author) / Hirt, Paul (Thesis advisor) / Vandermeer, Philip (Committee member) / Smith, Karen (Committee member) / Arizona State University (Publisher)
Created2013
Description
Zero-Valent Metals (ZVM) are highly reactive materials and have been proved to be effective in contaminant reduction in soils and groundwater remediation. In fact, zero-Valent Iron (ZVI) has proven to be very effective in removing, particularly chlorinated organics, heavy metals, and odorous sulfides. Addition of ZVI has also been proved in enhancing the methane gas generation in anaerobic digestion of activated sludge. However, no studies have been conducted regarding the effect of ZVM stimulation to Municipal Solid Waste (MSW) degradation. Therefore, a collaborative study was developed to manipulate microbial activity in the landfill bioreactors to favor methane production by adding ZVMs. This study focuses on evaluating the effects of added ZVM on the leachate generated from replicated lab scale landfill bioreactors. The specific objective was to investigate the effects of ZVMs addition on the organic and inorganic pollutants in leachate. The hypothesis here evaluated was that adding ZVM including ZVI and Zero Valent Manganese (ZVMn) will enhance the removal rates of the organic pollutants present in the leachate, likely by a putative higher rate of microbial metabolism. Test with six (4.23 gallons) bioreactors assembled with MSW collected from the Salt River Landfill and Southwest Regional Landfill showed that under 5 grams /liter of ZVI and 0.625 grams/liter of ZVMn additions, no significant difference was observed in the pH and temperature data of the leachate generated from these reactors. The conductivity data suggested the steady rise across all reactors over the period of time. The removal efficiency of sCOD was highest (27.112 mg/lit/day) for the reactors added with ZVMn at the end of 150 days for bottom layer, however the removal rate was highest (16.955 mg/lit/day) for ZVI after the end of 150 days of the middle layer. Similar trends in the results was observed in TC analysis. HPLC study indicated the dominance of the concentration of heptanoate and isovalerate were leachate generated from the bottom layer across all reactors. Heptanoate continued to dominate in the ZVMn added leachate even after middle layer injection. IC analysis concluded the chloride was dominant in the leachate generated from all the reactors and there was a steady increase in the chloride content over the period of time. Along with chloride, fluoride, bromide, nitrate, nitrite, phosphate and sulfate were also detected in considerable concentrations. In the summary, the addition of the zero valent metals has proved to be efficient in removal of the organics present in the leachate.
ContributorsPandit, Gandhar Abhay (Author) / Cadillo – Quiroz, Hinsby (Thesis advisor) / Olson, Larry (Thesis advisor) / Boyer, Treavor (Committee member) / Arizona State University (Publisher)
Created2019