Minimization of GHG emissions in froth treatment tailing by manipulation of electron acceptors

尾矿池中温室气体排放的主要来源是沥青回收中使用的环烷和石蜡溶剂的生物降解，以及在较小程度上残留沥青的生物降解。由于甲烷的全球升温潜能值（GWP）是二氧化碳的28-36倍，因此根据阿尔伯塔的气候变化战略，减少或消除甲烷排放可产生重大的环境和经济效益，必须加以解决。CH 4是由烃类的微生物氧化产生的，该微生物氧化与末端电子受体（TEA）如乙酸或CO2在低氧化还原条件（~ -250 mV）下的还原偶联，当不存在其他TEA如Fe（III）和硫酸盐时。当这样的TEA以足够高的浓度存在时，甲烷生成被抑制。本提案将在实验室微观世界或生物反应器研究中审查不同TEA条件、营养物添加剂以及稀释剂和沥青浓度对来自不同类型尾矿池的尾矿中生物气生产的影响。将生物气生产率、TEA消耗率和烃降解率与未修正的微观世界进行比较。将确定碳氢化合物降解剂，这些生物体可能用于提高降解率。其他研究将评估质量转移限制的影响，因为溶剂必须从沥青骨料中扩散到水相中进行生物降解。这些结果将被用来开发一个耦合的传质和反应模型，将提供各种茶/氧化还原条件下的温室气体生产的基本信息。它将用于确定主导机制，并帮助制定策略，通过操纵池塘化学来最大限度地减少温室气体排放。根据阿尔伯塔的气候变化战略，这将对工业产生重大的环境和经济效益，并将在更大范围内改善加拿大和全球的环境和生活质量。研究成果也可应用于其他生态系统，如海洋和淡水沉积物，以减少温室气体的产生，并进一步促进减少全球变暖。该项目还将为10名高素质人员提供培训。

The main sources of greenhouse gas (GHG) emissions in tailings ponds are from the biodegradation of naphthenic and paraffinic solvents used in bitumen recovery, and to a lesser extent, of residual bitumen. Since CH4 has a global warming potential (GWP) of 28-36 times that of CO2, reducing or eliminating CH4 emissions can be of significant environmental and economic benefit under Alberta's climate change strategy and must be addressed. CH4 is produced from the microbial oxidation of hydrocarbons coupled to the reduction of terminal electron acceptors (TEAs) such as acetic acid or CO2 at low redox conditions (~ -250 mV) when other TEAs such as Fe(III) and sulphate are absent. When such TEAs are present at sufficiently high concentrations, methanogenesis is inhibited. This proposal will examine the impact of different TEA conditions, nutrient amendments and diluent and bitumen concentrations on biogenic gas production in tailings from different types of tailing ponds in laboratory microcosm or bioreactor studies. Rates of biogenic gas production, TEA consumption, and hydrocarbon degradation will be compared to unamended microcosms. The hydrocarbon degraders will be identified and these organisms could potentially be used to enhance degradation rates. Additional studies will evaluate the effect of mass transfer limitation as solvents have to diffuse out of bitumen aggregates to the aqueous phase to be biodegraded. These results will be used to develop a coupled mass transfer and reaction model that would provide basic information on GHG production under a variety of TEAs/redox conditions. It will be used to identify dominant mechanisms and aid in developing strategies to minimize GHG emissions by manipulating pond chemistry. This can have significant environmental and economic benefit to industry under Alberta's climate change strategy and on a wider scale will improve the environment and the quality of life in Canada and globally. The research outcomes may also be applied to other ecosystems such as marine and freshwater sediments to reduce GHG production and further contribute to decrease global warming. This project will also provide training to 10 highly qualified individuals.