Division of Sustainable Energy and Environmental Engineering, Osaka University, 2-1 Yamadaoka, Suita, Osaka 565-0871, Japan E-mail:
Water Sci Technol. 2022 Oct;86(7):1707-1718. doi: 10.2166/wst.2022.296.
1,4-dioxane (DX) is a contaminant of emerging concern in water environments. The enrichment of DX-degrading bacteria indigenous to activated sludge is key for the efficient biological removal of DX in wastewater. To identify an effective substrate, which enables the selective enrichment of DX-degrading bacteria and has lower toxicity and persistence than DX, this study explored the effectiveness of tetrahydrofuran (THF) at enhancing the DX degradation ability of activated sludge without historical exposure to DX. Although the activated sludge initially exhibited negligible ability to degrade DX (100 mg-C/L) as the sole carbon source, the repeated batch cultivation on THF could enrich bacterial populations capable of degrading DX, inducing the DX degradation ability in activated sludge as effectively as DX did. The THF-enrichment culture after 4 weeks degraded 100 mg-C/L DX almost completely within 21 d. Sequencing analyses revealed that soluble di-iron monooxygenase group 5C, including THF/DX monooxygenase, would play a dominant role in the initial oxidation of DX in THF-enrichment culture, which completely differed from the enrichment culture cultivated on DX. The results indicate that THF can be applied as an effective substrate to enhance the DX degradation ability of microbial consortia, irrespective of the intrinsic ability.
1,4-二恶烷（DX）是水环境中新兴的关注污染物。富含 DX 降解菌的活性污泥是废水生物去除 DX 的关键。为了寻找一种有效的基质，这种基质既能选择性地富集 DX 降解菌，又具有比 DX 更低的毒性和持久性，本研究探索了四氢呋喃（THF）在不依赖于 DX 历史暴露的情况下，增强活性污泥对 DX 降解能力的有效性。尽管活性污泥最初几乎没有能力以 THF 作为唯一的碳源来降解 DX（100 mg-C/L），但经过 THF 的重复批培养可以富集能够降解 DX 的细菌种群，从而有效地诱导活性污泥对 DX 的降解能力，与 DX 一样有效。经过 4 周的 THF 富集培养，100 mg-C/L 的 DX 在 21 天内几乎完全降解。测序分析表明，可溶性二铁单加氧酶组 5C，包括 THF/DX 单加氧酶，将在 THF 富集培养物中对 DX 的初始氧化中起主导作用，这与在 DX 上培养的富集培养物完全不同。研究结果表明，THF 可以作为一种有效的基质，增强微生物群落对 DX 的降解能力，而不受内在能力的影响。
