Evaluating the biogeochemistry of oil sands tailings in end pit lakes

评价末坑湖油砂尾矿的生物地球化学

• 批准号: RGPIN-2022-03422
• 负责人: Ulrich, Ania
• 金额: $ 2.62万
• 依托单位: University of Alberta
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2022
• 资助国家: 加拿大
• 起止时间: 2022-01-01 至 2023-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=749117
• 关键词: Evaluating; biogeochemistry; oil; sands; tailings

The oil sands are a vital component to the Canadian economy; however, the environmental impacts of oil sands operations are also growing. Tailings impoundments are used almost exclusively for waste management with a combined footprint more than 220 km2. Processed oil sands ore yields tailings slurries that are discharged into a settling basin and must eventually be reclaimed and integrated into mine closure landscapes. However, due to the low solids/high clay content of tailings, they are slow to dewater, making reclamation of oil sands tailings particularly challenging. One proposed reclamation method is end pit lakes (EPLs), which involve depositing thick layers of tailings capped with water in decommissioned open pits. Theoretically, EPLs are a suitable reclamation strategy because the tailings can slowly dewater while the water cap serves as habitat for an aquatic ecosystem. However, the first full-scale demonstration EPL showed that there are several challenges with this strategy, including turbidity generation and water cap quality. As such, depositing coagulant- (alum) and flocculant-treated (polyacrylamide, PAM) tailings in EPLs was proposed to improve tailings dewatering and reduce turbidity generation. This technology is called permanent aquatic storage structure (PASS). To date, the biogeochemical implications of depositing PASS-treated tailings in EPLs remain unknown, and the biodegradation and environmental fate of PAM, PAM degradation products, and aluminum are not well understood. This program will elucidate the biogeochemical behavior of untreated and treated tailings in EPLs and will evaluate whether EPLs are a suitable, environmentally responsible tailings reclamation strategy. The objectives of these studies are to investigate PAM biodegradation in treated oil sands tailings, and evaluate the biogeochemical evolution of untreated and treated oil sands tailings in EPLs. Microcosm studies with microorganisms indigenous to oil sands tailings will investigate biodegradation in PAM-treated tailings under aerobic and anaerobic conditions. My previous research has now developed into decades worth of knowledge in studying complex anaerobic bioremediation systems and uniquely positions us to tackle this equally complex PAM bioremediation system. With upcoming oil sands mine closures over the next 50 years, it is vital to understand the long-term effects of current tailings reclamation practices. The proposed research will provide critical information on the biogeochemical implications of using EPLs for reclamation. The knowledge gained from this research will assist in identifying and reducing the long-term environmental impacts of mine closure practices and will guide future research and development. Canadians have a vested interest in ensuring the proposed research project provides the oil sands industry with information needed to make sound tailings management and mine closure planning decisions.

油砂是加拿大经济的重要组成部分；然而，油砂作业对环境的影响也在加大。尾矿库几乎完全用于废物管理，总占地面积超过 220 平方公里。加工后的油砂矿石产生尾矿浆，这些尾矿浆被排放到沉降池中，最终必须回收并融入矿山关闭景观中。然而，由于尾矿的固体含量低/粘土含量高，脱水速度慢，使得油砂尾矿的回收特别具有挑战性。提出的一种填海方法是尾坑湖（EPL），它涉及在退役的露天矿坑中沉积厚厚的尾矿层，上面覆盖着水。从理论上讲，EPL 是一种合适的复垦策略，因为尾矿可以缓慢脱水，而水盖可以作为水生生态系统的栖息地。然而，首次全面示范 EPL 表明该策略存在一些挑战，包括浑浊度产生和水盖质量。因此，建议将混凝剂（明矾）和絮凝剂处理的（聚丙烯酰胺，PAM）尾矿沉积在 EPL 中，以改善尾矿脱水并减少浊度的产生。该技术称为永久性水生储存结构（PASS）。迄今为止，将经过 PASS 处理的尾矿沉积在 EPL 中的生物地球化学影响仍然未知，并且 PAM、PAM 降解产物和铝的生物降解和环境归宿尚不清楚。该计划将阐明 EPL 中未经处理和处理尾矿的生物地球化学行为，并将评估 EPL 是否是一种合适的、对环境负责的尾矿回收策略。这些研究的目的是研究经过处理的油砂尾矿中的 PAM 生物降解情况，并评估 EPL 中未经处理和经过处理的油砂尾矿的生物地球化学演化。对油砂尾矿固有微生物的微观研究将研究经 PAM 处理的尾矿在需氧和厌氧条件下的生物降解情况。我之前的研究现已发展成为研究复杂厌氧生物修复系统数十年的知识，并为我们解决同样复杂的 PAM 生物修复系统奠定了独特的基础。 随着未来 50 年即将关闭的油砂矿，了解当前尾矿回收实践的长期影响至关重要。拟议的研究将提供有关使用 EPL 进行回收的生物地球化学影响的关键信息。从这项研究中获得的知识将有助于识别和减少矿山关闭做法对环境的长期影响，并将指导未来的研究和开发。确保拟议的研究项目为油砂行业提供制定健全的尾矿管理和矿山关闭规划决策所需的信息，符合加拿大人的既得利益。