Matching Items (5)
Filtering by

Clear all filters

152724-Thumbnail Image.png
Description
ABSTRACT Enzyme-Induced Carbonate Precipitation (EICP) using a plant-derived form of the urease enzyme to induce the precipitation of calcium carbonate (CaCO3) shows promise as a method of stabilizing soil for the mitigation of fugitive dust. Fugitive dust is a significant problem in Arizona, particularly in Maricopa County. Maricopa County is

ABSTRACT Enzyme-Induced Carbonate Precipitation (EICP) using a plant-derived form of the urease enzyme to induce the precipitation of calcium carbonate (CaCO3) shows promise as a method of stabilizing soil for the mitigation of fugitive dust. Fugitive dust is a significant problem in Arizona, particularly in Maricopa County. Maricopa County is an EPA air quality non-attainment zone, due primarily to fugitive dust, which presents a significant health risk to local residents. Conventional methods for fugitive dust control, including the application of water, are either ineffective in arid climates, very expensive, or limited to short term stabilization. Due to these limitations, engineers are searching for new and more effective ways to stabilize the soil and reduce wind erosion. EICP employs urea hydrolysis, a process in which carbonate precipitation is catalyzed by the urease enzyme, a widely occurring protein found in many plants and microorganisms. Wind tunnel experiments were conducted in the ASU/NASA Planetary Wind Tunnel to evaluate the use of EICP as a means to stabilize soil against fugitive dust emission. Three different soils were tested, including a native Arizona silty-sand, a uniform fine to medium grained silica sand, and mine tailings from a mine in southern Arizona. The test soil was loosely placed in specimen container and the surface was sprayed with an aqueous solution containing urea, calcium chloride, and urease enzyme. After a short period of time to allow for CaCO3 precipitation, the specimens were tested in the wind tunnel. The completed tests show that EICP can increase the detachment velocity compared to bare or wetted soil and thus holds promise as a means of mitigating fugitive dust emissions.
ContributorsKnorr, Brian (Author) / Kavazanjian, Edward (Thesis advisor) / Houston, Sandra (Committee member) / Zapata, Claudia (Committee member) / Arizona State University (Publisher)
Created2014
133118-Thumbnail Image.png
Description
Current practice and a new technology for mitigating fugitive dust on construction sites are compared on the basis of economic, environmental and social impacts for this assessment. Fugitive dust can have serious health impacts, such as repertory illnesses and valley fever, on affected persons and is regulated by the Environmental

Current practice and a new technology for mitigating fugitive dust on construction sites are compared on the basis of economic, environmental and social impacts for this assessment. Fugitive dust can have serious health impacts, such as repertory illnesses and valley fever, on affected persons and is regulated by the Environmental Protection Agency and enforced by state and local agencies. Current practice consists of either relatively continuous application of potable water, a valuable resource, or application of expensive polymers, however, water application is considered the best available technology (BAT). The new technology, developed by the Center of Bio-medicated and Bio-inspired Geotechnics at Arizona State University, consists of application of Enzyme-Induced Carbonate Precipitate (EICP) to create an erosion-resistant crust. This crust is considered a "one and done" solution, until it is disturbed, however will last longer and stay more effective than quickly evaporating water. Future work will need to include how much disturbance is required to disturb the crust until ineffective towards mitigating fugitive dust. Results of the comparison show that a single EICP treatment produces 37 times less pollutants, uses 41 times less water and is 1.14 times cheaper than using water treatment to mitigate fugitive dust on a 7 acre site for 2 weeks (14 days). 14 days is the threshold at where EICP treatment becomes less expensive than water application for the purpose of mitigating fugitive dust. The EICP treatment benefits include lowering global warming inducing emissions, providing better air quality, becoming more cost effective, staying constantly effective to mitigate fugitive dust, and saving potable water.
ContributorsFabian, Aaron Jacob (Author) / Fox, Peter (Thesis director) / Kavazanjian, Edward (Thesis director) / Woolley, Miriam (Committee member) / Civil, Environmental and Sustainable Eng Program (Contributor, Contributor) / Barrett, The Honors College (Contributor)
Created2018-12
137618-Thumbnail Image.png
Description
Currently conventional Subtitle D landfills are the primary means of disposing of our waste in the United States. While this method of waste disposal aims at protecting the environment, it does so through the use of liners and caps that effectively freeze the breakdown of waste. Because this method can

Currently conventional Subtitle D landfills are the primary means of disposing of our waste in the United States. While this method of waste disposal aims at protecting the environment, it does so through the use of liners and caps that effectively freeze the breakdown of waste. Because this method can keep landfills active, and thus a potential groundwater threat for over a hundred years, I take an in depth look at the ability of bioreactor landfills to quickly stabilize waste. In the thesis I detail the current state of bioreactor landfill technologies, assessing the pros and cons of anaerobic and aerobic bioreactor technologies. Finally, with an industrial perspective, I conclude that moving on to bioreactor landfills as an alternative isn't as simple as it may first appear, and that it is a contextually specific solution that must be further refined before replacing current landfills.
ContributorsWhitten, George Avery (Author) / Kavazanjian, Edward (Thesis director) / Allenby, Braden (Committee member) / Houston, Sandra (Committee member) / Civil, Environmental and Sustainable Engineering Programs (Contributor) / Barrett, The Honors College (Contributor)
Created2013-05
157581-Thumbnail Image.png
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

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
171518-Thumbnail Image.png
Description
Two challenges in the implementation of enzyme induced carbonate precipitation(EICP) are the cost of enzyme and the variability of the enzyme. Urease enzyme costs can be lowered drastically with the use of crude extract from plant materials, but experience has shown variability in the source of the crude urease enzyme, the crude urease

Two challenges in the implementation of enzyme induced carbonate precipitation(EICP) are the cost of enzyme and the variability of the enzyme. Urease enzyme costs can be lowered drastically with the use of crude extract from plant materials, but experience has shown variability in the source of the crude urease enzyme, the crude urease enzyme extraction methods, and the concentration of the EICP solution can cause significant variability in the efficacy of the EICP solution. This thesis examines the variability in the efficacy of crude enzyme derived from jack beans (Canavalia ensiformis) and sword beans (Canavalia gladiata), two of the most commonly used sources of urease enzyme for EICP. The sources of variability investigated herein include the crude extraction method (including the effect of the bean husks on extraction) and different chemical constituent concentrations. These effects were assessed using enzyme activity measurements and precipitation efficiency tests. The activity tests were performed via spectrophotometry using Nessler's reagent. The precipitation tests looked at the influence of chemical constituent concentrations of 0.67 M calcium chloride and 1 M urea with non-fat dry milk in the EICP solutions and a higher concentration solution with chemical constituent concentrations of 2 M for both calcium chloride and urea with non-fat dry milk. The high concentration solution was selected based on preliminary testing results to maximize carbonate precipitation in one cycle of treatment. Significant sources of a decline in activity (and increase in variation) of the crude urease enzyme were found in extraction from sword beans with husks, high chemical constituent concentrations, and juicing instead of cheesecloth filtration. This thesis also examines the accuracy of commonly used correlation factors for converting electrical conductivity to urease enzyme activity. Crude jack bean and sword bean urease enzyme activity measurement via electrical conductivity was found to have a correlation coefficient that differed from the previously reported correlation when compared to activity measured via the more accurate spectrophotometry using Nessler’s reagent measurements.
ContributorsPearson, Rayanna (Author) / Kavazanjian, Edward (Thesis advisor) / Khodadadi Tirkolaei, Hamed (Committee member) / Salifu, Emmanuel (Committee member) / Arizona State University (Publisher)
Created2022