Department of Civil and Environmental Engineering, College of Engineering, The University of Iowa, Iowa City, IA, USA.
Department of Civil and Environmental Engineering, College of Engineering, Rice University, Houston, TX, USA.
Sci Total Environ. 2020 Nov 20;744:140823. doi: 10.1016/j.scitotenv.2020.140823. Epub 2020 Jul 12.
1,4-Dioxane is a highly mobile and persistent groundwater pollutant that often forms large dilute plumes. Because of this, utilizing aggressive pump-and-treat and ex-situ technologies such as advanced oxidation can be prohibitively expensive. In this study, we bioaugmented the poplar rhizosphere with dioxane-degrading bacteria Mycobacterium dioxanotrophicus PH-06 or Pseudonocardia dioxanivorans CB1190 to enhance treatment of 1,4-dioxane in bench-scale experiments. All treatments tested removed 10 mg/L dioxane to near health advisory levels (<4 μg/L). However, PH-06-bioaugmented poplar significantly outperformed all other treatments, reaching <4 μg/L in only 13 days. Growth curve experiments confirmed that PH-06 could not utilize root extract as an auxiliary carbon source for growth. Despite this limitation, our findings suggest that PH-06 is a strong bioaugmentation candidate to enhance the treatment of dioxane by phytoremediation. In addition, we confirmed that CB1190 could utilize both 1,4-dioxane and root extract as substrates. Finally, we demonstrated the large-scale production of these two strains for use in the field. Overall, this study shows that combining phytoremediation and bioaugmentation is an attractive strategy to treat dioxane-contaminated groundwater to low risk-based concentrations (~1 μg/L).
1,4-二恶烷是一种具有高迁移性和持久性的地下水污染物，常形成大规模的稀疏散布的污染羽。正因为如此，采用激进的泵吸和异位处理技术，如高级氧化技术，可能会非常昂贵。在这项研究中，我们利用能够降解 1,4-二恶烷的细菌 Mycobacterium dioxanotrophicus PH-06 或 Pseudonocardia dioxanivorans CB1190 对杨树根际进行生物强化，以增强实验室规模实验中 1,4-二恶烷的处理效果。所有测试的处理方法都将 10mg/L 的二恶烷去除到接近健康建议水平（<4μg/L）。然而，PH-06 生物强化的杨树在所有其他处理方法中表现最佳，仅在 13 天内就达到了<4μg/L。生长曲线实验证实 PH-06 不能利用根提取物作为生长的辅助碳源。尽管存在这种局限性，但我们的研究结果表明，PH-06 是增强植物修复处理二恶烷的强有力的生物强化候选物。此外，我们证实 CB1190 可以同时利用 1,4-二恶烷和根提取物作为底物。最后，我们展示了这两种菌株的大规模生产，以用于现场应用。总体而言，这项研究表明，将植物修复和生物强化相结合是一种有吸引力的策略，可以将受二恶烷污染的地下水处理到低风险基准浓度（~1μg/L）。
