• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 275
  • 54
  • 10
  • 4
  • 3
  • 3
  • 2
  • 2
  • 1
  • 1
  • 1
  • 1
  • 1
  • 1
  • Tagged with
  • 400
  • 400
  • 400
  • 90
  • 84
  • 60
  • 60
  • 51
  • 48
  • 44
  • 43
  • 42
  • 39
  • 35
  • 35
  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
91

Chemical and physical properties of abandoned underground coal mine pools

Perry, Eric F. January 1900 (has links)
Thesis (Ph. D.)--West Virginia University, 2009. / Title from document title page. Document formatted into pages; contains xiii, 379 p. : ill. (some col.), maps (some col.). Vita. Includes abstract. Includes bibliographical references.
92

Trialling small-scale passive systems for treatment of acidmine drainage: A case study from Bellvue Mine, WestCoast, New Zealand.

West, Rae Ann January 2014 (has links)
Bellvue Mine is an abandoned coal mine on the West Coast of the South Island which discharges severe acid mine drainage (AMD) into the nearby Cannel Creek. This site is unique in that iron is in a ferrous or reduced form at the mouth of the mine, but due to the slope of the site, the AMD becomes aerated and subsequently the iron oxidises into ferric form as it moves downstream. Research was conducted to examine the geochemistry of the AMD at the site and investigate the performance of selected passive treatment systems at this site, with a view to informing decisions for passive treatment at other comparable mines on the West Coast. A range of small-scale trial passive remediation systems were installed, including an anoxic limestone drain (ALD), a bioreactor, and two mussel shell reactors. Results from the trials showed that the mussel shell reactor treating oxidised water was the most effective at reducing the concentration of dissolved metals in the AMD. A range of factors including hydraulic residence time, geochemistry of the Bellvue Mine discharge, and unexpected equipment issues all contributed to the results of the trials, and are important factors that need to be taken into consideration when designing a full-scale system for this site and others.
93

The use of waste mussel shell in sulfate-reducing bioreactors treating mine-influenced waters

Uster, Benjamin January 2015 (has links)
Mining-Influenced Water (MIW) poses major environmental issues in New Zealand and worldwide due to a legacy of unmitigated mining activities. As conventional MIW treatment technologies can be very costly in terms of chemical and energy inputs, cheaper and environmentally-friendly alternative remediation strategies have been developed. These so-called passive treatment technologies include a range of engineered systems relying on biogeochemical processes able to mitigate the acidity and to immobilize the metals in MIW. The present research, built on previous work conducted at the University of Canterbury, investigated the use of waste materials in mesocosm lab-scale sulfate-reducing bioreactors (SRBR) to treat actual mining-influenced water (MIW) sourced at an active coal mine in New Zealand. Specifically, this study investigated using waste mussel shells as an alkaline amendment (instead of the more conventional material limestone), with organic waste materials such as wood byproducts and compost in complex substrate mixtures in upward-flow SRBR. The influence of hydraulic retention times of approximately 3 and 10 days (HRT; i.e. the contact time between the MIW and the substrate mixtures in the SRBR) on the treatment performances was also evaluated. Overall, each system successfully treated the MIW (e.g. increased the pH > 6 and removed >78 % of the metals, except Mn) during the first 5-month treatment period, while during the second 5-month period, the treatment systems containing limestone and/or operating at a short HRT started to show signs of decreased efficiency. Generally, the system containing mussel shell and operating at a long HRT was constantly the most efficient system. Over the whole 41-week period of treatment, key metal removal efficiencies ranged between 97.6 and 99.7 % (Al), 83.9 and 95.2 % (Fe), and 9.2 and 38.8 % (Mn). Sulfate removal, in terms of moles of sulfate removed per cubic meter of substrate per day, was on average below the design values of 0.3 mol/m3/d, and ranged between 0.03 and 0.55 mol/m3/d (median values were 0.26 to 0.3 mol/m3/d during the first 5-month period but dropped to 0.094 to 0.1 mol/m3/d during the second 5-month treatment period). The SRBR containing mussel shell instead of limestone resulted in significantly higher alkalinity generation (between 32 to 85 % higher) and higher metal removals (between 0.6 % higher for Al and 14 % higher for Ni). These results were mainly attributed to the unique mineralogy of the mussel shell which comprises of aragonite with traces of calcite, while limestone comprises of pure calcite with traces of quartz. The statistical analyses showed that the sulfate reduction was not significantly affected by the alkalinity source. Similarly, systems operating at a longer HRT (10 days instead of 3 days) showed better treatment performances than systems operating at a short HRT in terms of alkalinity generation (44 to 62% higher), metal removal (between 0.5 % higher for Al to 15 % higher for Ni, and between 17 to 23 % higher for Mn), and sulfate reduction (50 to 77 % higher). Overall, the systems operation on a longer HRT were dominated by a more reduced environment facilitating the precipitation of metal sulfides, while the reactors running on a shorter HRT were constantly maintained out of equilibrium by the continuous addition of fresh MIW. Chemical and mineralogical analyses performed on the spent substrates suggested that the metals were removed through precipitation as, and adsorption onto, metal sulfides (Fe, Zn, Ni, Cu), (oxy)hydroxides (Al, Fe, Zn), and carbonates (Mn, Zn). Mn, a metal known to be harder to remove from solution was likely removed through the precipitation of rhodochrosite (MnCO3) and via adsorption onto the organic matter. These results generally corroborated the results obtained using the geochemical modeling PHREEQC. Overall, this study showed that mussel shells are not only a sustainable and effective alternative to mined limestone, but their use in SRBR would also result in a better treatment of MIW. Additionally, even though an increase in HRT resulted in a better contaminant removal, a HRT of approximately 3 days was sufficient to remove about 80% of all metals (except Mn). Therefore, the difficult choice of an optimal HRT must balance the need to meet a specific effluent quality while keeping the treatment time reasonably short, and an intermediate retention time of approximately 6 days could be optimal.
94

Passive treatment of acid mine drainage with sulphate reducing bacteria

Peterson, Ryan 09 May 2013 (has links)
This research was completed to assess passive treatment methods for mitigation of acid mine drainage (AMD) at a former mine site in British Columbia. The objectives were to determine if suitable passive treatment methods were available, and if concentrations of Cd, Zn, and other key contaminants in groundwater could be reduced to below regulatory standards during bench-scale testing. Biological treatment with sulphate reducing bacteria (SRB) was selected, and bench-scale treatment testing was conducted using columns amended with low cost organic sources. Removal of more than 99% Cd, 93% Co, 96 % Cu, 86% Ni and 98% Zn was observed, resulting in metals concentrations in treated effluent consistently lower than applicable groundwater standards. Sustainability attributes of treatment with SRB and the potential to recover valuable metals are discussed, and recommendations for further testing and implementation are provided.
95

Mapping of hydrogeology of underground mines in the Upper Freeport coal seam, northern Appalachian Basin, WV-PA-MD

Thies, Jane E. January 2007 (has links)
Thesis (M.S.)--West Virginia University, 2007. / Title from document title page. Document formatted into pages; contains x, 86, [22] p. : ill. (some col.), col. maps. Includes abstract. Includes bibliographical references (p. 58-63).
96

Stream water quality and benthic macroinvertebrate ecology in a coal-mining, acid-sensitive region

Merovich, George T., January 1900 (has links)
Thesis (Ph. D.)--West Virginia University, 2007. / Title from document title page. Document formatted into pages; contains xi, 170 p. : ill. (some col.), maps. Vita. Includes abstract. Includes bibliographical references.
97

Reductive dissolution of manganese (IV) oxides and precipitation of iron (III) : implications for redox processes in an alluvial aquifer affected by acid mine drainage /

Villinski, John Eugene. January 2001 (has links) (PDF)
Thesis (Ph.D. - Hydrology and Water Resources)--University of Arizona. / Includes bibliographical references (leaves 46-66).
98

Water quality changes over time in Upper Freeport and Pittsburgh coal mines in West Virginia

Mack, Ben M. January 2008 (has links)
Thesis (M.S.)--West Virginia University, 2008. / Title from document title page. Document formatted into pages; contains x, 81 p. : ill. (some col.), col. map. Includes abstract. Includes bibliographical references.
99

Watershed restoration limitations at the abandoned reclaimed Alta Mine, Jefferson County, MT

Labbe, Richard James. January 2008 (has links) (PDF)
Thesis (MS)--Montana State University--Bozeman, 2008. / Typescript. Chairperson, Graduate Committee: Clayton B. Marlow. Includes bibliographical references (leaves 100-109).
100

Characterization of a highly acid watershed located mainly in Perry County, Ohio

Eberhart, Ryan J. January 1998 (has links)
Thesis (M.S.)--Ohio University, August, 1998. / Title from PDF t.p.

Page generated in 0.123 seconds