Sulfate-based coagulants can suppress methanogenesis in treated oil sands fine tailings

This study investigates the affinity of clay minerals in oil sands for the water‐continuous tailings and hydrocarbon‐continuous froth streams produced from the extraction of bitumen from oil sands. Clay minerals in oil sands processing impact bitumen flotation in separation vessels, emulsion formation during froth treatment, and fine tailings behaviour.X‐ray diffraction of oriented clay slides and random powder samples were used to quantify the clay minerals in the oil sands ore and process streams. Particle size distribution and clay activity balances were also conducted around the extraction process.The degree of partitioning during the conditioning and flotation stages in a batch extractor was determined by the surface properties of the clay minerals present. The water‐continuous tailings stream was further separated into fine and coarse tailings fractions through sedimentation. The bulk of the clay minerals reported to the fine tailings stream. Illite and mixed layered illite‐smectite partitioned less to the hydrocarbon‐continuous froth than kaolinite. Also, the illite‐smectite in the froth stream appeared to be different from the illite‐smectite in the water continuous streams.

Microbial research for maintaining soil productivity, health, and environment as well as for ecosystem function has been one of the main research focuses in the Department of Renewable Resources (formerly Department of Soil Science) during the last 100 yr. In recent years, microbial research has been expanded to effectively reclaim disturbed land, remediate contaminated sites, and manage soft sediments such as huge volumes of oil sands tailings. This article highlights the microbial processes in tailings ponds that can affect strategies to manage growing inventory of oil sands tailings and reduce associated environmental footprint. Enormous volumes of fluid fine tailings produced during bitumen extraction from oil sands are retained in tailings ponds. Some tailings streams contain residual labile hydrocarbons originated from the hydrocarbon solvents used in the extraction process. Indigenous microorganisms acclimated to the pond environment metabolize certain fractions of the fugitive labile hydrocarbons into biogenic greenhouse gases (GHG) such as methane (CH4) and carbon dioxide (CO2). Long-term (1–7 yr) biodegradation studies conducted using mature fine tailings (MFT) collected from different tailings ponds reveal that the microorganisms sequentially and preferentially biodegrade hydrocarbons under methanogenic conditions. The stoichiometric mathematical model developed on these biodegradation studies can predict GHG emissions from tailings ponds. Production of biogenic gases also affects the porewater and solid-phase chemistry of MFT and accelerates their de-watering and consolidation during active methanogenesis, which is beneficial for recovery of porewater for reuse in the bitumen extraction process and for effective reclamation of consolidated material.

Controls on sulfide accumulation in coastal soils during simulated sea level rise

Water availability is beginning to impact oil sands development and as a result, several technologies to increase the percentage of recycle water are being evaluated. One such option which is being re-evaluated is the use of centrifuges to produce a dry tailings which can accommodate overburden and soil replacement. Previous evaluations of centrifuge performance to capture water from the clay and silt tailings (mature fine tailings) components demonstrated some success, but at the time unacceptable costs. A better appreciation of the long term costs of mature fine tailings storage has prompted a reevaluation of centrifuge technology. The use of additives to improve centrifuge performance has significantly improved the results which can be achieved. Aside from the obvious positive environmental benefit of reclaiming the fluid fine (mature fine) tailings, the increase in the amount of water recycled will decrease the requirement to use the limited water in the Athabasca river. This paper discusses a laboratory scale study of the water chemistry and clay/silt feed properties which affect centrifuge performance, along with 20 tonne per hour pilot scale results. Introduction The term dry stackable tailings is commonly used in oil sands tailings management to mean a mineral stream left over from the bitumen extraction process which can be stored without the need for dikes or other fluid containment structures. The water required for the bitumen extraction process results in mineral tailings streams in the form of slurries or suspensions, that require containment. In general, surface mined oil sands tailings fall into three categories: sand tailings, fine tailings, and froth treatment tailings. Although the froth treatment tailings have important environmental implications due to their contamination with solvents or diluents from the froth treatment process, they are generally combined with the other tailings prior to discharge into the recycle water area (tailings settling pond). Typically it is a straightforward process to create dry stackable tailings from the sand tailings, and they are often used to build the containment for the remaining fluid fine tailings. It is another common practice for the surface mined oil sands industry to define sand as mineral particles greater than 44 microns. Fines are therefore less than 44 micron, and this definition can be useful when discussing the long very clearly, however, that it is the clay content that determines all of the important properties of the fine tailings or fluid fine tailings. (or mature fine tailings, when the solids content exceeds about 25%)(1–3). Over the entire mine, of course, the average clay to fines content is fixed, and the fines content can be a useful approximation tool for large scale planning purposes and the prediction of sand volumes and the fine tailings volume that will require containment. The clay content, often expressed as a clay to fines ratio, can vary across an oil sands lease by as much as a factor of

Water availability is beginning to impact oil sands development and, as a result, several technologies to increase the percentage of recycled water are being evaluated. One such option being re-evaluated is the use of centrifuges to produce dry tailings that can accommodate overburden and soil replacement. Previous evaluations of centrifuge performance to capture water from the clay and silt tailings (mature fine tailings) components demonstrated some success but, at the time, at unacceptable costs. A better appreciation of the long-term costs of mature fine tailings storage has prompted a re-evaluation of centrifuge technology. The use of additives to improve centrifuge performance has significantly improved the results that can be achieved. Aside from the obvious positive environmental benefit of reclaiming the fluid fine (mature fine) tailings, the increase in the amount of water recycled will reduce the demand for fresh water from the Athabasca River. This paper discusses a laboratory-scale study of the water chemistry and clay/silt feed properties affecting centrifuge performance, as well as the results of a 20 tonne per hour pilot. Introduction The term dry stackable tailings is commonly used in oil sands tailings management to mean a mineral stream left over from the bitumen extraction process which can be stored without the need for dikes or other fluid containment structures. The use of water in the bitumen extraction process results in mineral tailings streams in the form of slurries or suspensions that require containment. In general, surface mined oil sands tailings fall into three categories: sand tailings, fine tailings and froth treatment tailings. Although the froth treatment tailings have important environmental implications due to their contamination with solvents or diluents from the froth treatment process, they are generally combined with the other tailings prior to discharge into the recycle water area (tailings settling pond). It is typically a straightforward process to create dry stackable tailings from the sand tailings, and they are often used to build the containment for the remaining fluid fine tailings. Another common practice in the surface mined oil sands industry is to define sand as mineral particles larger than 44 micrometres (µm). Fines are therefore smaller than 44 µm, and this definition can be useful when discussing the long-term tailings properties during mine planning. It has been demonstrated very clearly, however, that it is the clay content that determines all of the important properties of the fine tailings or fluid fine tailings (or mature fine tailings when the solids content exceeds about 25 wt%)(1–3). Over the entire mine, of course, the average clay-to-fines ratio is fixed and the fines content can be a useful approximation tool for large-scale planning purposes and the prediction of sand volumes and the fine tailings volume that may require containment. The clay content, often expressed as a clay-to-fines ratio, can vary across an oil sands lease by as much as a factor of four. It is therefore essential that the clay content, clay-to-water ratio or clay-to-fines ratio be understood in order to predict the properties of the fluid fine tailings on a daily or monthly basis.

Toward sustainable remediation of oil sands fine Tailings-A review

The oil sands in northern Alberta have been mined to produce bitumen over the past five decades. Since the 1980s, technical advances have been made in mining, material handling, and bitumen extraction. However, acquiring practical methods to control and reduce the fluid fine tailings build-up has been an ongoing challenge. Recent regulatory changes have driven the industry to review current tailings-management techniques and investigate numerous alternative technologies and processes to manage and reclaim fine tailings. Many of these fine tailings–management techniques involve some form of polymer or chemical addition to promote dewatering and strength gain to meet the regulatory requirements. Based on the reported data, the chemically amended fine tailings deposits have the characteristics of sensitive, metastable deposits, necessitating additional mitigative measures by oil sands operators beyond the regulatory requirements. This paper explores the geotechnical aspects of meeting regulatory strength performance criteria by employing flocculation-based dewatering of fluid fine tailings.

Enhanced sulfidization in a sedimentary turbidite layer from the Nansha Trough in the southern South China Sea

Thermal-chemical-hydraulic separation process is used to extract bitumen from surface mined oil sands ores. Huge amounts of oil sands fine tailings are produced from the extraction process. The most fundamentally challenging issue facing the geo-environmental community is containment, long-term storage, and volume reduction of oil sands fine tailings. One of the fine tailings disposal techniques is to homogenize fine tailings with coarse tailings forming nonsegregating tailings (NST). NST exhibits enhanced performance in consolidation and strength, and reduction in water retention as compared to fine tailings. This paper examines one-dimensional consolidation behavior of NST with varying fine and coarse tailings compositions. A mechanistic model based on theory of mixture is developed and proposed to predict consolidation behavior of NST. This model is demonstrated to achieve an optimum design of NST for accelerated consolidation rate and water recovery.

Pitched battles are a regular occurrence in northern Alberta, Canada, as development of the province’s oil sands continues to expand. One ongoing battle—with another salvo launched in February 2011 with the leak of a European Commission report1—concerns how dirty oil sands are, relative to other fuels. Another concerns the influence of the oil sands industry in monitoring its own activity.2 In an effort to cut through the rhetoric of health advocates, industry representatives, environmentalists, government officials, and local residents, the Royal Society of Canada (RSC) selected and covered expenses for an expert panel to winnow out the facts. In a report issued 15 December 20103 the panel cited substantial evidence that efforts to extract oil from the Alberta deposits have degraded air, land, and water quality to varying degrees. The extent of the degradation is sometimes controversial; water quality data, in particular, are subject to differing interpretations and attributions of causality. However, the panel says that, based on publicly available evidence, there appear to be no significant human health threats to the general population either now or from development anticipated in the next decade or so. But the panel also warns that their conclusions come with a major caveat: there are major gaps in health and environmental data, risk assessments, government oversight, information transparency, industry efforts, and disaster preparedness. The health of the region could hinge on these gaps being addressed, particularly since, according to Travis Davies, a spokesman for the Canadian Association of Petroleum Producers, 97% of projected oil extraction and processing is still to come. After the RSC panel reviewed reams of publicly available information on factors such as health status, air and water pollution, greenhouse gas emissions, land disturbance, and energy and water consumption, it concluded that “[t]he claim by some critics of the oil sands industry that it is the most environmentally destructive project on earth is not supported by the evidence. However, for Canada and Alberta, the oil sands industry involves major environmental issues on many fronts which must be addressed as a high priority.”3p293

Iron sulfide formation in young and rapidly-deposited permeable sands at the land-sea transition zone

土壤是植物定居的场所，也是植物-微生物互作的重要界面。古菌是土壤微生物重要组份，在碳、氮、硫、铁等元素的生物地球化学循环和植物的生长发育、适应生境中发挥重要作用。植物定居对土壤古菌群落的影响研究鲜有开展，孑遗植物在研究植物-微生物-环境互作中具有独特的优势。采用扩增子高通量测序技术，研究以荒漠孑遗植物四合木为建群种或优势种的四合木-红砂-珍珠-针茅群落、四合木-针茅群落和四合木群落等三种荒漠植物群落类型中，四合木根区土壤和光板地土体土壤古菌群落特征，揭示四合木定居对土壤古菌物种数量、多样性、群落组成及功能的影响。结果表明，荒漠孑遗植物四合木定居不仅增加了根区土壤古菌的物种数量，提高了根区土壤古菌群落多样性，而且改变了土壤古菌群落组成，减少了奇古菌门Nitrososphaeraceae科未分类的属氨氧化古菌（unclassified_f_Nitrososphaeraceae）和暂定Nitrososphaera属氨氧化古菌（Candidatus Nitrososphaera）相对丰度，增加了Nitrososphaeraceae科暂定Nitrocosmicus属氨氧化古菌（Candidatus Nitrocosmicus）和广古菌门海洋古菌类群Ⅱ中未分类的属（norank_o_Marine_Group_II）相对丰度，广古菌门热原体纲未分类的属（unclassified_c__Thermoplasmata）相对丰度变化显著。植物群落演替对四合木根区土壤和光板地土体土壤古菌群落均无显著影响。Nitrososphaeraceae科氨氧化古菌是三种不同荒漠植物群落类型中土壤古菌的核心微生物组。四合木定居也显著改变土壤古菌群落的功能，减弱了高丰度功能，增强了低丰度功能，对有氧呼吸、核苷酸合成、氨基酸合成等途径影响显著。荒漠孑遗植物四合木定居改变了土壤古菌群落物种数量、多样性、组成、功能等特征。;Soil is the place where plants colonize and an important interface between plant and microorganism interaction. Archaea is an important component of soil microorganism and plays an important role in the biogeochemical cycle of carbon, nitrogen, sulfur and iron, and in the growth, the development and adaptation to the environment of plants. It is rarely reported the influence of plant colonization on the archaeal community in soil. The relict plants have special advantages in the study of interaction among plant, microbe and environment. In this paper, the archaea in rhizosphere soil in relict plant Tetraena mongolica and barren soil obtained from three different communities of desert plants including the community of Tetraena mongolica, Reaumuria songarica, Salsola passerine and Stipa capillata, the community of Tetraena mongolica and Stipa capillata and the community of Tetraena mongolica where Tetraena mongolica is the dominant species or constructive species were studied to explore the effect of relict plant Tetraena mongolica colonization on the number, the diversity, the composition and the function of archaeal community using the high-throughput sequencing method. The results showed that the diversity and the number of species in archaeal community of rhizosphere soil increased with relict plant Tetraena mongolica colonization. Meanwhile, the composition of archaeal community in soil were changed with relict plant Tetraena mongolica colonization. The relative abundance of ammonia oxidizing archaea of genera unclassified_f_Nitrososphaeraceae of phylum Thaumarchaeota and ammonia oxidizing archaea of Candidatus Nitrososphaera of phylum Thaumarchaeota in rhizosphere soil decreased, while the relative abundance of ammonia oxidizing archaea of genera Candidatus Nitrocosmicu of phylum Thaumarchaeota and norank_o_Marine_Group_II of phylum Euryarchaeota in rhizosphere soil increased. There was no obvious change on the relative abundance of unclassified_c__Thermoplasmata of phylum Euryarchaeota. However, the succession of plant communities had no significant effect on the archaea communities in the rhizosphere soil of relict plant Tetraena mongolica and barren soil. Ammonia oxidizing archaea of family Nitrososphaeraceae is the core microbiome of archaeal communities in soil obtained from three different communities of desert plants. Furthermore, the relict plant Tetraena mongolica colonization greatly changed the function of archaeal community in soil. The high abundant function of archaeal community in soil was weakened and the low abundant function of was enhanced. There was significant effect on aerobic respiration, the pathway of nucleotide biosynthesis and the pathway of amino acid biosynthesis.The relict plant Tetraena mongolica colonization has changed characteristics of archaeal community in desert soil including the number of species, the diversity and the species composition, the function, etc.

Microbial Ecological Processes: Aerobic/Anaerobic

Diverse yet-uncultivated bacteria and archaea, i.e., microbial dark matter, are present in terrestrial hot spring environments. Numerous metagenome-assembled genomes (MAGs) of these uncultivated prokaryotes by short-read metagenomics have been reported so far, suggesting their metabolic potential. However, more reliable MAGs, i.e., circularized complete MAGs (cMAGs), have been rarely reported from hot spring environments. Here, we report 61 high-quality (HQ)-MAGs, including 14 cMAGs, of diverse uncultivated bacteria and archaea retrieved from hot spring sediment (52°C, pH 7.2) by highly accurate long-read sequencing using PacBio Sequel II. The HQ MAGs were affiliated with one archaeal and 13 bacterial phyla. Notably, nine of the 14 cMAGs were the first reported cMAGs for the family- to class-level clades that these cMAGs belonged to. The genome information suggests that the bacteria represented by MAGs play a significant role in the biogeochemical cycling of carbon, nitrogen, iron, and sulfur at this site. In particular, the genome analysis of six HQ MAGs including two cMAGs of Armatimonadota, of which members are frequently abundant in hot spring environments, predicts that they are aerobic, moderate thermophilic chemoorganoheterotrophs, and potentially oxidize and/or reduce iron. This prediction is consistent with the environmental conditions where they were detected. Our results expand the knowledge regarding the ecological potential of uncultivated bacteria in moderately-high-temperature environments.

Large marine regions, including the exceptionally productive Southern Ocean, are iron-limited. As a result, there has been substantial interest in iron-fertilizing high nutrient low chlorophyll (HNLC) areas in an effort to sequester atmospheric carbon dioxide. More recently, research has shifted to quantifying the beneficial effects of iron recycling by marine biota. Marine top predators such as whales and seabirds have been examined specifically in this regard as they have high biomass, form dense aggregations, and excrete bioavailable iron in concentrations seven orders of magnitude higher than ambient seawater. Despite it being well established that marine fauna link the iron and carbon cycles, the connection of this process to the sulfur cycle has rarely been considered. The chemoattraction of specific marine fauna to algal-derived dimethyl sulfide (DMS) is key in triggering dense, multi-species foraging aggregations that induce iron recycling, augmenting carbon assimilation. The goal of this paper is twofold; first, to highlight DMS chemoattraction as a behavior that catalyzes carbon sequestration via natural iron fertilization, and second, to identify knowledge gaps that recent biogeochemical advances can address. Fostering this interdisciplinary research will enhance our understanding of global climate regulation, ecosystem services provided by marine top predators, and the biogeochemical cycles of carbon, iron, and sulfur in HNLC waters.