Biological treatment of naphthenic acids in oil sands process waters

阿萨巴斯卡油砂是世界第三大石油储量。Clark的热水萃取过程将沥青从油砂中分离出来，并产生废水流，称为油砂处理水（OSPW）。萃取水中低浓度环烷酸（NAs）的复杂混合物已被确定为主要的有毒成分，也是OSPW修复的最大障碍。因此，《艾伯塔省环境保护和加强法》禁止其排放。由于没有工业规模的有效处理，OSPW储存在超过7.2亿立方米的尾矿库中。随着油砂行业的扩张，环境问题变得越来越重要。

The Athabasca oilsands is the world’s third largest petroleum reserve. The Clark’s hot water extraction process separates bitumen from oilsands and generates a wastewater stream known as oilsands process waters (OSPW). A complex mixture of naphthenic acids (NAs) at a low concentration in the extraction water has been identified as the major toxic component, and as the most significant barrier to remediation of OSPW. Hence, the Alberta Environmental Protection and Enhancement Act prohibits its discharge. Since there is no effective treatment at an industrial scale, OSPW is stored in tailings ponds that exceed 720 million m3. As the oilsands industry expands, environmental concerns become increasingly important. In previous work, we have shown that a microbial biofilm in a fully-instrumented, continuous flow reactor has been established on OSPW as the only source of carbon and energy and was able to remove 38 ± 7% of NAs at a rate of 2.82 mg/L-d, substantially higher than previous reports. However, higher NA removal is needed for industrial application. To achieve this, we need a better understanding of the role that different microbial populations in the biofilm play in degrading different groups of NAs so that we can artificially construct a specific biofilm composition that would degrade NAs more effectively and efficiently and so achieve a much higher level of NAs removal. The overall goal of this research program is to develop a biofilm reactor system for the biodegradation and detoxification of NAs in OSPW. If successful, this program will be the first to demonstrate that an artificially constructed, complex biofilm reactor can effectively enhance the cleanup of complex organic wastes like NAs in OPSW. This could lead to pilot-scale studies and commercialization, resulting in economic, social and environmental benefits to Canada.