Mitigating GHG emissions from oil sands tailings through redox processes

油砂的露天开采具有显著的环境足迹。目前，尾矿池含有超过10亿立方米的流体细尾矿（FFT），需要回收。来自沉降FFT的孔隙水的表达将油砂工艺影响的水贡献给水帽体积和化学。尾矿池是厌氧的，并且含有微生物群落，其降解FFT中的残余烃类，产生温室气体（GHG），主要是甲烷。同样，甲烷生成可以继续在底坑湖，其中FFT是回收的水下和条件是有氧表面附近。本项目的总体目标是减少温室气体净排放量。将采用双管齐下的策略：1）了解铁矿物和其他氧化还原化合物（硝酸盐和硫酸盐）在抑制甲烷生成中的作用，2）了解这些替代电子受体，沿着分子氧（O2），在氧化产生的甲烷中的作用。探索土著微生物的代谢潜力，并调查产甲烷和铁，氮，硫循环之间的联系，在FFT将有助于制定战略，将包括原位修正的氧化还原化合物和异位应用的氧化还原过程，以抑制产甲烷和刺激甲烷氧化。该方法将减少加拿大阿尔伯塔阿萨巴斯卡油砂地区尾矿池和未来底坑湖的温室气体排放。

Surface mining of oil sands has a significant environmental footprint. Currently tailings ponds contain more than 1 billion m3 of fluid fine tailings (FFT) that need to be reclaimed. Expression of porewater from settling FFT contributes oil sands process-affected water to the water cap volume and chemistry. Tailings ponds are anaerobic and harbor microbial communities that degrade residual hydrocarbons in FFT producing greenhouse gases (GHG), primarily methane. Similarly, methanogenesis can continue in end-pit lakes where FFT is reclaimed under water and the conditions are aerobic near the surface. The overarching objective of this current project is to reduce net GHG emissions. A two-pronged strategy will be employed: 1) to understand the role of iron minerals and other redox compounds (nitrate and sulfate) in the inhibition of methanogenesis and 2) to understand the roles of these alternative electron acceptors, along with molecular oxygen (O2), in the oxidation of produced methane. Exploring the metabolic potential of indigenous microorganisms and investigating linkages between methanogenesis and iron, nitrogen, and sulfur cycling in the FFT will help develop strategies that will include in situ amendments of redox compounds and ex-situ application of redox processes to inhibit methanogenesis and stimulate methane oxidation. The approach will mitigate GHG emissions from tailings ponds and future end-pit lakes in the Athabasca Oil Sands region in Alberta, Canada.