Department of Civil and Environmental Engineering, University of Alberta, Edmonton, AB T6G 1H9, Canada.
Waterloo Institute for Nanotechnology, University of Waterloo, Waterloo, ON N2L 3G1, Canada; Department of Chemical Engineering, University of Waterloo, Waterloo, ON N2L 3G1, Canada.
Chemosphere. 2024 Aug;361:142502. doi: 10.1016/j.chemosphere.2024.142502. Epub 2024 Jun 3.
Bitumen extraction in Alberta's oil sands region uses large volumes of water, leading to an abundance of oil sands process-affected water (OSPW). OSPW contains naphthenic acid fraction compounds (NAFCs) which have been found to contribute to OSPW toxicity. This study utilized a multistep treatment, coupling biological degradation with UV photocatalytic oxidation, and nutrient addition to boost the native microbial community's degradation capacity. OSPW initially contained 40-42 mg/L NAFCs with a toxicity of 3.8-3.9 TU. Initial biodegradation (Step 1) was used to remove the easily biodegradable NAFCs (11-25% removal), followed by a light or heavy dose of oxidation (Step 2) to breakdown the recalcitrant NAFCs (66-82% removal). Lastly, post-oxidation biodegradation with nutrients (Step 3) removed the residual bioavailable NAFCs (16-31% removal). By the end of the multistep treatment, the final NAFC concentrations and toxicity ranged from 5.3 to 6.8 mg/L and 1.1-1.2 TU. Analysis showed that OPSW was limited in phosphorus (below detection limit), and the addition of nutrients improved the degradation of NAFCs. Two treatments throughout the multistep treatment never received nutrients and showed minimal NAFC degradation post-oxidation. The native microbial community survived the stress from UV photocatalytic oxidation as seen by the post-oxidation NAFC biodegradation. Microbial community diversity was reduced considerably following oxidation, but increased with nutrient addition. The microbial community consisted predominately of Proteobacteria (Gammaproteobacteria and Alphaproteobacteria), and the composition shifted depending on the level of oxidation received. Possible NAFC-degrading microbes identified after a light oxidation dose included Pseudomonas, Acinetobacter and Xanthomonadales, while Xanthobacteracea and Rhodococcus were the dominant microbes after heavy oxidation. This experiment confirms that the microbial community is capable of degrading NAFCs and withstanding oxidative stress, and that degradation is further enhanced with the addition of nutrients.
阿尔伯塔省油砂地区的沥青提取使用了大量的水，导致大量油砂处理影响水（OSPW）的产生。OSPW 含有环烷酸分数化合物（NAFCs），这些化合物已被发现会导致 OSPW 毒性。本研究采用多步处理方法，将生物降解与 UV 光催化氧化相结合，并添加营养物质来提高土著微生物群落的降解能力。OSPW 最初含有 40-42mg/L 的 NAFCs，毒性为 3.8-3.9TU。初始生物降解（步骤 1）用于去除易生物降解的 NAFCs（去除率为 11-25%），然后进行轻或重剂量的氧化（步骤 2）以分解难生物降解的 NAFCs（去除率为 66-82%）。最后，用营养物质进行氧化后的生物降解（步骤 3）去除剩余的生物可利用的 NAFCs（去除率为 16-31%）。经过多步处理，最终的 NAFC 浓度和毒性范围为 5.3 至 6.8mg/L 和 1.1-1.2TU。分析表明，OSPW 中磷含量有限（低于检测限），添加营养物质可提高 NAFC 的降解率。在整个多步处理过程中，有两种处理方法从未添加过营养物质，并且在氧化后 NAFC 降解作用最小。土著微生物群落经受住了 UV 光催化氧化的压力，这可以从氧化后的 NAFC 生物降解中看出。氧化后微生物群落的多样性显著降低，但添加营养物质后增加。微生物群落主要由变形菌门（γ-变形菌纲和 α-变形菌纲）组成，并且组成随氧化程度的变化而变化。经过轻度氧化处理后，鉴定出的可能具有 NAFC 降解能力的微生物包括假单胞菌、不动杆菌和黄单胞菌目，而在重度氧化后，优势微生物为黄杆菌科和红球菌属。该实验证实，微生物群落能够降解 NAFCs 并承受氧化应激，并且添加营养物质可进一步提高降解能力。
