Mines Repository (Colorado School of Mines)
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Assessing the co-production of ammonia and methane for resource recovery optimization
No full textIncludes bibliographical references.2024 Fall.The wastewater treatment is crucial to safeguard people and ecosystems from health and environmental risks. The treatment requires a significant amount of energy for their processes, and it could represent 30-40% of the total energy spent by municipalities. Moreover, the energy used in wastewater treatment plants is the most significant contributor to carbon emissions in the sector. However, wastewater has immense potential for recovering valuable resources such as methane and ammonia. The recovery of these resources could assist these facilities in offsetting energy expenses and carbon emissions, moving them towards net zero.
This research used microcosms to assess the co-production of methane and ammonia using different solids, including solids from a new technology for primary filtration called cloth media filters (CMF). Primary solids, secondary solids, and anaerobic digester sludge were sourced from 4 major water recovery facilities near Denver, and CMF solids from Mines Park Water Reclamation Facility.
The results showed that the co-production assessment is achievable in a single batch assay using solids concentrations equivalent to the ones used in the operation of real digesters, with similar methane fractions and ammonia in the same order of magnitude. The low C/N ratio was beneficial for accumulating ammonia in the centrate making it an interesting subject for ammonia recovery. For biogas, the pH of the microcosms was the most determinant factor in optimizing the methane fraction in the biogas. The Pearson test proved the correlation between pH and methane fraction, and the combinations with a pH higher than 7 had more methane content, following the optimum pH range for methanogenic Archaea. The addition of phosphate buffer to maintain the pH values close to neutral was also studied. Results suggest that higher concentrations caused a more significant reduction on the biogas yield, and the phosphate buffer also reduced the VS reduction of a few of the solids, especially the CMF. On the other hand, the final ammonia concentration increased with the addition of phosphate
Proving infeasibility in motion planning
No full textIncludes bibliographical references.2024 Spring.Motion planning is a fundamental problem in robotics that has received a lot of attention. The motion planning problem is NP-complete, but previous works in motion planning have been very successful in efficiently finding a valid path in motion planning problems. One class of solutions for solving high-dimensional motion planning problems is sampling-based algorithms.
For motion planning algorithms, completeness is a crucial and desirable attribute. A complete motion planner returns a plan when one exists and also reports failure when no plan exists. However, complete motion planning is challenging, and many approaches aim for weaker notions of completeness. Most sampling-based motion planners are probabilistically complete which means when a feasible plan exists, they find the plan given enough time. But when a plan does not exist, they can run forever or until a timeout. Reporting failure, or proving infeasibility, when no plan exists is another side of the problem that has not been well-studied previously. This thesis focuses on finding infeasibility proofs in motion planning.
An infeasibility proof is a closed manifold in the obstacle region of the configuration space that separates the start and goal into disconnected components of the free configuration space. We introduce two algorithms for generating infeasibility proofs. The first algorithm grows facets of the infeasibility proof manifold directly, and works for up-to 3-D configuration spaces. The second algorithm uses a learned manifold to generate the infeasibility proof, which works for up-to 4-D configuration spaces. We further extended the algorithm for up-to 5-D configuration spaces. The learned manifold not only helps with the construction of infeasibility proof but also helps with narrow passage motion planning. Our algorithm, Sample-Driven Connectivity Learning (SDCL), leverages this manifold to help sampling in narrow passages.
Additionally, we prove that the learned manifold converges to an infeasibility proof exponentially. Combining prior approaches for sampling-based planning and our converging infeasibility proofs, we propose the term asymptotic completeness to describe the property of returning a plan or infeasibility proof in the limit. We compare the empirical convergence of different sampling strategies to validate our analysis
Evaluation of hybrid treatment configurations of granular activated carbon and alternative adsorbents for per- and polyfluoroalkyl substances removal from surface water and groundwater
No full textIncludes bibliographical references.2024 Summer.Per- and polyfluoroalkyl substances (PFAS) have emerged as a significant global environmental concern due to their persistence, ubiquitous presence, and associated human health hazards. As a result, regulatory agencies worldwide have enacted stringent drinking water standards to mitigate human exposure to PFAS. Traditional adsorption-based treatment technologies like granular activated carbon (GAC) and anion-exchange resins have been used extensively, but often see diminished performance with “challenging” waters that contain competitive adsorbates such as dissolved organic matter (DOM) and/ or total dissolved solids (TDS). This study evaluated a relatively new selective adsorbent (Fluoro-Sorb®) in combination with lead-lag column configurations to improve the treatment of challenging waters. A rapid small-scale column test (RSSCT) system was used to assess the performance of Filtrasorb 400 (GAC), Fluoro-Sorb® 200 (FS), and CalRes2301 (IX) with three different source waters: PFAS spiked tap water, stormwater; and brackish groundwater. Additionally, this study evaluated three lead-lag systems (GAC-IX, FS-IX, and GAC-FS) and developed a costing approach to compare the cost-effectiveness of these configurations.
Based on the media performance, usage rate, and cost, FS was the most cost-effective for brackish groundwater, followed by IX and GAC. However, FS’s cost savings diminished for stormwater and PFAS spiked tap water, where IX consistently performed better, and short-chain perfluorocarboxylic acids (PFCAs) remained challenging for GAC and FS to remove. The lead-lag column study demonstrated that hybrid configurations were more cost-effective for brackish groundwater and short-chain PFCA removal when compared to a standalone IX column. Lastly, GAC-IX was the most cost-effective configuration for treating brackish groundwater, offering moderate to high performance and at a lower overall media cost than FS-IX
CO₂ geosequestration in the Lakota Formation, Powder River Basin, WY, USA
No full textIncludes bibliographical references.2024 Summer.Deep saline aquifers have been identified as suitable repositories for geologic carbon sequestration due to their vast storage capacity, widespread distribution, and low potential for leakage. Among these potential sites, the Cretaceous deep saline aquifer Lakota Formation in the Powder River Basin has been suggested as a potential target.
This thesis presents a quantitative feasibility study for carbon geosequestration within the Lakota Sandstone Formation. The assessment consists of formation evaluation, seismic data analysis, geomechanical modeling, rock physics analysis, and thermo-hydro-mechanical simulation within the target reservoir. Various datasets were utilized during the evaluation, including geophysical logs, mud reports, drilling reports, drill stem tests, diagnostic formation integrity tests, core data, regional stress state maps, and a high-resolution three-dimensional seismic survey.
Formation evaluation is conducted using geophysical logs to estimate key parameters such as water saturation, formation water salinity, total and effective porosity. Permeability is estimated with empirical relationships and core data. The geomechanical model is constructed using a pore pressure model calibrated with drill stem test data from the study area. Static and dynamic elastic properties and strength parameters, including Young’s modulus, Poisson’s ratio, unconfined compressive strength, and friction angle, are estimated from both geophysical logs and empirical relationships. One-dimensional (1D) and three-dimensional (3D) mechanical earth models are developed based on regional stress state maps, poroelastic method, and offset diagnostic formation integrity tests.
Structural and attribute analysis is conducted on the post-stack seismic data. Additionally, 3D seismic inversions are completed for pre- and post-stack data sets. The seismic property changes within the Lakota Formation are investigated using Gassmann fluid substitution across a wide range of potential temperature, pressure, and CO2 saturation conditions. Storage constraints are also investigated, including storage capacity and injectivity.
A potential zone of approximately 45 feet in the Lakota Formation is identified for CO2 geosequestration evaluation. The formation has an estimated permeability of 0.5 - 5 mD and an average effective porosity of 11%, with formation water salinity exceeding 10,000 ppm. An existing drill stem test from one of the wells within the study area reveals a higher thermal gradient than previously reported in the literature. The 1D mechanical earth model results highlight overpressure compartmentalization in shale zones extending from the Frontier to Fuson Formations. Variance and ant tracking attributes indicate a minimal discontinuity in the southwest region of the study area. Post-stack and pre-stack seismic inversions show consistent lateral and vertical thickness variations of all formations above the Dakota Formation. Secondary seals, Mowry, Carlile, and Niobrara Formations, collectively contribute to a seal thickness of up to 300 meters /1000ft in this study area.
The extent of the Lakota Formation suggests a maximum potential storage capacity of ∼ 6.5 Mtons of CO2. The formation pore pressure is estimated ∼ 37 MPa, with a fracture pressure of ∼ 53 MPa, potentially allowing for a pressure differential of ∼ 15 MPa before compromising the geomechanical integrity of the Lakota Formation.
Based on the estimated reservoir and stress state conditions, a thermo-hydro-mechanical simulation is conducted at a constant CO2 injection rate for up to 10 years at a maximum injection rate of 0.1 Mtons/yr. Changes in pressure, temperature, saturation, and stress due to CO2 injection after one day, one month, one year, five years, and ten years are analyzed. The simulation shows significant differences between thermal and pressure fronts and the concentration of thermal stresses around the borehole, showing stress changes with the thermal shock fronts. Simulation results reveal limited injectivity compared to other potential projects.
This research highlights that the permeability and relatively narrow injectable zone within the Lakota Formation, coupled with a high-temperature anomaly, present challenges in achieving high annual injection rates without compromising the geomechanical integrity of the Lakota Formation. These conditions limit the feasibility of the Lakota Formation within the study area for large-scale CO2 injection projects
Stratigraphic control and distal hydrothermal footprint of the Ursa Zn-Pb-Ag prospect, Selwyn Basin, Yukon Territory, Canada
No full textIncludes bibliographical references.2024 Spring.Clastic-dominated deposits are an important source of Zn, Pb, and Ag worldwide. While it is widely accepted that the hydrothermal alteration halos around these deposits can be laterally extensive, the mineralogical and geochemical signature of the distal alteration footprint is currently not well understood. This severely limits greenfield exploration for this deposit type. The Ursa project in the Selwyn Basin, of the Yukon Territory of Canada, is a Zn-Pb-Ag prospect located 60 km north of the famous Macmillan Pass district. Extensive Zn and Ag anomalies in soil- and silts occur across the property which could indicate the presence of an undiscovered deposit. The present study aimed to understand stratigraphic control on the location of the prospect and to determine the distal alteration signatures of the Ursa prospect. The research involved detailed fieldwork across Ursa to map its stratigraphic setting and to determine the chemostratigraphic characteristics of favorable units through whole-rock geochemical analysis. It is demonstrated that the weakly altered sedimentary rocks at Ursa are stratigraphically equivalent to the host rocks of the Macmillan and Howards Pass districts. Optical microscopy, scanning electron microscopy, and the analysis of sulfur isotopes of pyrite, sphalerite and other sulfur-bearing minerals have been used to systematically evaluate the textural, mineralogical, and isotopic characteristics of the weakly altered, reduced, calcareous, and barite-bearing sedimentary units hosting the Ursa prospect. The most widespread and conspicuous hydrothermal phases include pyrite, sphalerite, and pyrite replacing earlier barite. The weakly altered rocks contain siderite and witherite. The results of this study provide new guidelines on how the distal signature of clastic-dominated deposits in the Selwyn Basin can be identified and used as potential vectors to mineralization
Targets of opportunity source catalog, prioritization, scheduler and related mechanics for the EUSO-SPB2 mission, The
No full textIncludes bibliographical references.2024 Spring.The Extreme Universe Space Observatory on a Super Pressure Balloon 2 (EUSO-SPB2) was developed to observe ultra high energy cosmic rays and very high energy (VHE) neutrinos from suborbital space. These earth-skimming VHE tau-neutrinos can interact with the Earth’s limb to produce tau leptons which can exit the Earth and decay to initiate extensive air showers (EASs). Below PeV energies, ground-based detectors such as IceCube and ANTARES have utilized km3-scale mediums to observe these EASs via their optical Cherenkov emissions. However, at higher energies, much of the sky becomes inaccessible to ground-based detectors because of Earth attenuation effects. As the interest in these multi-messenger particles increases, the development of space-based detectors is ongoing. EUSO-SPB2 was launched on May 13th, 2023 from Wanaka, NZ on a high-altitude balloon with a state-of-the-art Cherenkov Telescope (CT) which pioneered a solution to the attenuation problem and had the ability to respond in real-time to potential neutrino alerts throughout the sky. When the CT was pointed below the limb, the mission of the EUSO-SPB2 Targets of Opportunity (ToO) program was to follow up on astrophysical transient source alerts and selected steady state sources by searching for upward-going optical Cherenkov emission from PeV-scale EASs induced by tau neutrinos. To do this, a software program that collects ToO alerts from several online databases, sorts through these alerts, prioritizes and schedules them was developed alongside a mechanical system to point the CT. The flight lasted 1 day, 12 hours and 53 minutes. This short flight did not allow for ample time to test the prepared ToO software or to point the CT at a ToO. Studies are currently ongoing to test this software with data from longer balloon flights. These follow-up mechanisms utilized by the CT to view ToOs are the subject of this thesis
Beryl var. goshenite
No full textPhotographed by Ron Wolf.Cross-section of glassy translucent goshenite (variety of beryl)