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  • 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.
21

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.
22

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.
23

Water management at abandoned flooded underground mines fundamentals, tracer tests, modelling, water treatment /

Wolkersdorfer, C. January 1900 (has links)
Thesis (doctoral)--TU Bergakademie Freiberg, 2006. / "International Mine Water Association." Description based on print version record. Includes bibliographical references (p. [337]-420) and index.
24

Water management at abandoned flooded underground mines fundamentals, tracer tests, modelling, water treatment /

Wolkersdorfer, C. January 1900 (has links)
Thesis (doctoral)--TU Bergakademie Freiberg, 2006. / "International Mine Water Association." Includes bibliographical references (p. [337]-420) and index.
25

Mechanics of InSAR-identified bedrock subsidence associated with mine-dewatering in north-central Nevada /

Katzenstein, Kurt W. January 2008 (has links)
Thesis (Ph. D.)--University of Nevada, Reno, 2008. / "August, 2008." Includes bibliographical references (leaves 140-147). Library also has microfilm. Ann Arbor, Mich. : ProQuest Information and Learning Company, [2008]. 1 microfilm reel ; 35 mm. Online version available on the World Wide Web. Library also has electronic version on CD-ROM
26

Water management at abandoned flooded underground mines fundamentals, tracer tests, modelling, water treatment /

Wolkersdorfer, C. January 1900 (has links)
Thesis (doctoral)--TU Bergakademie Freiberg, 2006. / "International Mine Water Association." Includes bibliographical references (p. [337]-420) and index.
27

Floating sulphur biofilms : structure, function and biotechnology /

Molwantwa, Jennifer Balatedi. January 2007 (has links)
Thesis (Ph.D. (Biochemistry, Microbiology & Biotechnology)) - Rhodes University, 2008.
28

Estimation of vertical infiltration into deep Pittsburgh coal mines of WV-PA a fluid mass balance approach /

McCoy, Kurt J. January 2002 (has links)
Thesis (M.S.)--West Virginia University, 2002. / Title from document title page. Document formatted into pages; contains x, 150 p. : ill. (some col.), maps (some col.). Includes abstract. Includes bibliographical references (p. 87-90).
29

Modelling the soil water and salt balance of planted pastures irrigated with sodium sulphate rich mine effluent

Beletse, Yacob Ghebretinsae. January 2004 (has links)
Thesis (M.Sc.(Agric))(Plant Production)--University of Pretoria, 2004. / Title from opening screen (viewed March 11th, 2005). Includes summary. Includes bibliographical references.
30

Water management at abandoned flooded underground mines fundamentals, tracer tests, modelling, water treatment /

Wolkersdorfer, C. January 1900 (has links)
Thesis (doctoral)--TU Bergakademie Freiberg, 2006. / "International Mine Water Association." Includes bibliographical references (p. [337]-420) and index.

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