Use of algae for recovery and utilization of oil sands naphthenic acids

阿尔伯塔省的油砂是世界上第二大石油储量，2005年占加拿大原油总产量的39%。然而，从焦油砂中提取可用的原油和等价物需要相当大的努力和能源投入，而且目前的提取技术会产生大量的尾矿水作为副产品。尾矿水中发现的最丰富的污染物是环烷酸（NAs），含量约为20-120毫克/升。尾矿水中na的浓度阻碍了尾矿水直接释放回自然水体系统，导致大量尾矿水积聚在选矿设施周围的池塘和人工湖中。我们建议研究利用藻类从尾矿水中提取NAs的方法。藻类可以积累、吸附，并在较小程度上代谢NAs。将尾矿水中的藻类和积累的NAs进行过滤，为NA污染水体的修复提供了有效手段。过滤后的藻类可以用于生产生物柴油，也可以作为土地复垦的土壤添加剂，具有经济效益和环境效益。藻类油可以用与生产植物油类似的方式从藻类中生产出来，然后酯化生产生物柴油。用于将甘油三酯和脂肪酸转化为生物柴油的酯化反应也可以将NAs酯化，将其转化为类似于生物柴油的非酸性形式。采油后残留的有机物质可作为土壤添加剂用于油砂开采后的土地复垦，产生的废弃物最少。此外，可以从油砂设施排放的烟道气中回收大量的二氧化碳，从而减少二氧化碳净排放量。这类修复系统的长期目标将是多功能的——尾矿水可以得到充分处理以释放或再利用，藻类可以隔离二氧化碳，藻类可以生产生物柴油和有机土壤添加剂，NAs可以转化为适合作为柴油燃料的甲酯。本建议的目标是研究上述补救过程中涉及的各个组成部分的可行性。

Alberta's oil sands are the second largest oil reserves in the world, and in 2005 represented 39% of Canada's total crude oil production. The extraction of usable crude and equivalents from the tar sands, however, requires considerable effort and energy input, and current extraction techniques produce a large volume of tailings water as a byproduct. The most abundant contaminants found within tailings water are naphthenic acids (NAs), present at approximately 20-120 mg/L. The concentrations of NAs found in tailings water preclude the direct release of tailings water back to natural aquatic systems, resulting in accumulation of very large amounts of tailing water in ponds and artificial lakes surrounding upgrader facilities. We propose to investigate the use of algal species for extraction of NAs from tailings water. Algal species can accumulate, adsorb, and to a lesser degree metabolize NAs. The algae and accumulated NAs can then be filtered from tailings water, providing an effective means to remediate NA contaminated water. The filtered algae can be utilized for biodiesel production and as a soil additive for land reclamation efforts, providing both economic and environmental benefits. Algae oil can be produced from algae in a similar manner to production of vegetable oil, then esterified to produce biodiesel. The esterification reactions used to convert triglycerides and fatty acids to biodiesel can also esterify NAs, converting them into a non-acidic form similar to biodiesel. Residual organic material after oil extraction can be used as a soil additive to be used in land reclamation after oil sands mining, so minimal waste products are produced. Additionally, significant amounts of CO2 may be recovered from the flue gases emitted oil sands facilities, reducing net CO2 emissions. The long term goals of a remediation system such as this would be multi-functional- tailings water can be sufficiently treated for release or re-use, CO2 would be sequestered by algae, biodiesel and organic soil additive would be produced from algae, and NAs would be converted to methyl esters suitable as diesel fuel. The goals of this proposal are to study the feasibility of the various components involved in the remediation process described above.