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

艾伯塔省的油砂是世界第二大石油储量，2005年占加拿大原油总产量的39%。然而，从沥青砂中提取可用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)，约为20-120 mg/L。尾矿水中Nas的浓度阻碍了尾矿水直接释放回自然水生系统，导致尾矿水在提升机设施周围的池塘和人工湖中积累了非常大量的尾矿水。我们建议研究利用藻类从尾矿水中提取NAS。藻类物种可以积累、吸附，并在较小程度上代谢NAS。然后可以从尾矿水中过滤藻类和积累的NAS，为修复NA污染的水提供了一种有效的手段。过滤后的藻类可用于生产生物柴油，也可用作土地开垦的土壤添加剂，提供经济和环境效益。从藻类中生产藻油的方式与生产植物油的方式相似，然后将其酯化以生产生物柴油。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使NAS酯化，将它们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可以作为土壤添加剂，用于油砂开采后的土地复垦，产生的废物最少。此外，还可以从油砂设施排放的废气中回收大量二氧化碳，从而减少二氧化碳净排放量。这样的修复系统的长期目标是多功能-尾矿水可以得到充分的处理以释放或再利用，二氧化碳将被藻类隔离，生物柴油和有机土壤添加剂将从藻类中生产，NAS将转化为适合用作柴油的甲酯。这项提案的目标是研究上述补救进程中所涉及的各种组成部分的可行性。

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.