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增加。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。加工后的油砂矿产生的尾矿浆被排放到沉淀池中，最终必须回收并融入矿山关闭景观。然而，由于尾矿的固体含量低/粘土含量高，它们很难分解，使得油砂尾矿的回收特别具有挑战性。一种拟议的复垦方法是坑尾湖（EPLs），这涉及在退役的露天矿中沉积厚厚的尾矿层。从理论上讲，EPLs是一个合适的复垦策略，因为尾矿可以慢慢地恢复，而水帽作为水生生态系统的栖息地。然而，第一个全面的示范EPL表明，这一战略存在几个挑战，包括浊度的产生和水帽质量。因此，提出在EPLs中沉积混凝剂（明矾）和絮凝剂（聚丙烯酰胺，PAM）处理的尾矿以改善尾矿脱水并减少浊度的产生。这种技术被称为永久性水生存储结构（PASS）。到目前为止，沉积PAS处理的尾矿在EPLs的地球化学影响仍然未知，PAM，PAM降解产物和铝的生物降解和环境命运没有得到很好的理解。该计划将阐明EPLs中未经处理和处理的尾矿的地球化学行为，并将评估EPLs是否是一种合适的，对环境负责的尾矿回收策略。这些研究的目的是调查PAM在处理过的油砂尾矿中的生物降解，并评估未处理和处理过的油砂尾矿在EPLs中的地球化学演变。用油砂尾矿中的微生物进行的微观研究将调查PAM处理过的尾矿在有氧和厌氧条件下的生物降解情况。我以前的研究现在已经发展成为数十年来研究复杂的厌氧生物修复系统的知识，并使我们能够解决同样复杂的PAM生物修复系统。 随着未来50年油砂矿的关闭，了解当前尾矿回收实践的长期影响至关重要。拟议的研究将提供关键信息的生态地球化学的影响，使用环保PLs填海。从这项研究中获得的知识将有助于查明和减少关闭矿场做法对环境的长期影响，并将指导今后的研究和发展。加拿大人在确保拟议的研究项目为油砂行业提供做出合理的尾矿管理和矿山关闭规划决策所需的信息方面有既得利益。