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Yellowknife, Canada

Sherriff B.L.,University of Manitoba | Etcheverry D.J.,University of Manitoba | Sidenko N.V.,TetreES Consultants Inc. | Van Gulck J.,ARKTIS Solutions Inc.
Water-Rock Interaction - Proceedings of the 13th International Conference on Water-Rock Interaction, WRI-13 | Year: 2010

This study follows the geochemistry during systematic dewatering of the tailings after closure of Ruttan Cu-Zn mine in 2002. Acid generation is dominated by oxidization of pyrite and pyrrhotite (25 wt.% of tailings) with zinc being mobilized from remnant sphalerite. Oxidation of very fine grained sulfides caused an initial pulse of acid and sulfate release. Metals temporarily attenuated from tailings waters absorbed as evaporite minerals at the surface of the tailings are released during rain or freshet. Calcite provides little buffering capacity resulting in rapid acidification of pore and surface water. The pH of pore water decreased first to the Al(OH) 3 buffer at 4.5 and then stabilized 2-3 controlled by the dissolution of solid FeOOH. The metal contents of the surface water increased to 2009, but Ruttan Lake that receives drainage from the tailing is maintaining a constant composition. © 2010 Taylor & Francis Group, London. Source


Lozecznik S.,University of Manitoba | Sparling R.,University of Manitoba | Oleszkiewicz J.A.,University of Manitoba | Clark S.,University of Manitoba | VanGulck J.F.,ARKTIS Solutions Inc.
Waste Management | Year: 2010

In this study, an anaerobic sequencing batch reactor (ASBR) was operated with leachate from Brady Road Municipal Landfill in Winnipeg, Manitoba, Canada. Leachate was collected twice from the same cell at the landfill, during the first and 70th day of the study, and then fed into the ASBR. The ASBR was seeded at the start-up with biosolids from the anaerobic digester from Winnipeg's North End Water Pollution Control Center (NEWPCC). Due to the higher COD and VFA removal rates measured with the second batch of leachate, an increase of approximately 0.3 pH units was observed during each cycle (from pH 7.2 to 7.5). In addition, CO2 was produced between cycles at constant temperature where a fraction of the CO2 became dissolved, shifting the CO2/bicarbonate/carbonate equilibrium. Concurrent with the increase in pH and carbonate, an accumulation of fixed suspend solids (FSS) was observed within the ASBR, indicating a buildup of inorganic material over time. From it, Ca2+ and Mg2+ were measured within the reactor on day 140, indicating that most of the dissolved Ca2+ was removed within cycles. There is precedence from past researches of clogging in leachate-collection systems (Rowe et al., 2004) that changes in pH and carbonate content combined with high concentrations of metals such as Ca2+ and Mg2+ result in carbonate mineral precipitants. A parallel study investigated this observation, indicating that leachate with high concentration of Ca2+ under CO2 saturation conditions can precipitate out CaCO3 at the pH values obtained between digestion cycles. These studies presented show that methanogenesis of leachate impacts the removal of organic (COD, VFA) as well as inorganic (FSS, Ca2+) clog constituents from the leachate, that otherwise will accumulate inside of the recirculation pipe in bioreactor landfills. In addition, a robust methanogenesis of leachate was achieved, averaging rates of 0.35L CH4 produced/g COD removed which is similar to the theoretical removal of 0.4L CH4/g COD. Therefore, using methanogenesis of leachate prior to recirculation in bioreactor landfills will help to (1) control clog formation within leachate pipes and (2) produce an important additional source of energy on-site. © 2010 Elsevier Ltd. Source


Lozecznik S.,University of Manitoba | Oleszkiewicz J.A.,University of Manitoba | Clark S.,University of Manitoba | VanGulck J.F.,ARKTIS Solutions Inc. | Sparling R.,University of Manitoba
Proceedings, Annual Conference - Canadian Society for Civil Engineering | Year: 2010

Bioreactor landfills that inject leachate into the refuse have been employed to enhance refuse degradation and settlement, increase biogas production, and on-site treatment of leachate. One method of leachate injection involves placing trenches, containing a high-permeability material and perforated pipe, at a regular horizontal and vertical spacing within the landfill. Leachate is transmitted from a sump to horizontal trenches and conveyed along the perforated pipes. Leachate discharges from the pipes perforations and drains into the surrounding refuse. Field studies of pipes used in leachate injection and collection systems have shown that leachate transmission pipes can clog with biological, chemical and soil materials over time. Clogging impacts the operating performance and service life of the injection system. The first laboratory study designed to characterize the mechanisms and rates of leachate transmission pipe clogging was conducted as part of the applicant MSc. Thesis (Lozecznik 2006). There have been no field scale reported studies in this field. This study investigates the mechanisms of clog formation within leachate transmission pipes using a full-scale laboratory study. This field study is a leachate research station at Brady Road Landfill housing 16 HDPE pipes of different diameters conveying leachate at different flow rates and pressures. The changes in key leachate chemical composition within the pipe with time are correlated with the rate of clog development. In addition, the rate of clogging it has been correlated to the physical (e.g. diameter) and operating characteristics (e.g., flow rate) of the pipe. This paper/extended abstract briefly describes some preliminary results of this field study which will be completed on October 2010. Source


Sherriff B.L.,University of Manitoba | Jared Etcheverry D.,University of Manitoba | Sidenko N.V.,University of Manitoba | Sidenko N.V.,Stantec Consulting Ltd. | Gulck J.V.,ARKTIS Solutions Inc.
Applied Geochemistry | Year: 2011

The Ruttan Cu-Zn mine produced about 50. mT of fine-grained tailings over 30. a. Since the closure of the mine in 2002, the tailings have been systematically dewatered through trenches draining into the open pit and underground workings. This study evaluated the evolution of tailings that were underwater until 2002, and also tailings that had been exposed to oxidizing conditions for more than 20. a.Acid generation is dominated by the oxidization of the abundant pyrite and pyrrhotite comprising 25. wt.% of tailings with Zn being mobilized from the sphalerite remaining after beneficiation of the ore. Little Cu is being mobilized partly due to the armouring of remnant chalcopyrite by primary quartz, and also by preferential absorption of Cu rather than Zn on secondary Fe oxy-hydroxides. A very fine grained fraction of unoxidized sulfides is a likely cause of an initial pulse of acid generation, and metal and SO42- release occurring at the onset of dewatering. Metals are temporarily attenuated from waters associated with the tailings, either absorbed on Fe oxy-hydroxide precipitates or as evaporite hydroxy sulfate minerals at the surface of the tailings. While some secondary phases are stable, evaporites are only temporary metal sinks as they redissolve in wet weather conditions. Trace amounts of calcite provide little buffering capacity resulting in rapid acidification of pore and surface water. The pH of pore water and shallow groundwater decreased first to the Al oxy-hydroxide buffer at 4.5 and then stabilized at values of 2-3 being controlled predominantly by the dissolution of solid Fe oxy-hydroxides. The metal contents of the ground and surface water are still increasing but the Ruttan Lake reservoir that receives drainage water from the tailings is maintaining a constant composition. © 2011 Elsevier Ltd. Source


Simpson S.,University of Manitoba | Simpson S.,Lorax Environmental Services Ltd. | Sherriff B.L.,University of Manitoba | Gulck J.V.,ARKTIS Solutions Inc. | And 4 more authors.
Applied Geochemistry | Year: 2011

This study was to investigate the source, mobility and attenuation of As at the New Britannia Mine, Snow Lake, Manitoba. One major source of As contamination was determined to be an arsenopyrite residue stockpile (ARS) containing refractory Au in a waste rock impoundment. It appears that As is still moving through glacial clay at the base of the ARS into a confined aquifer even though the pile was capped in the year 2000. Arsenic is also being mobilized from a deposit of tailings, which formed following spills by previous owners, Nor Acme. Arsenic from the tailings is being mobilized by oxidation of arsenopyrite and reduction of arsenate to the more mobile arsenite by arsenate-reducing bacteria. This contamination is affecting a shallow unconfined aquifer and surface water flowing from the tailings through wetlands towards Snow Lake. Arsenic is being attenuated by adsorption to hydrated ferric oxides (HFO) in the tailings, wetland soils and aquatic plants. Although As in surface water, soils and plants along the flow path from the mine to Snow Lake are above Canadian drinking water guidelines, efficient natural attenuation by HFO in soils and plants of the wetlands have limited the concentration in Snow Lake to below drinking water standards. © 2011 Elsevier Ltd. Source

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