摘要

       季铵化合物 (QAC)（例如，十六烷基三甲基溴化铵，CTAB）是新出现的污染物，广泛用作表面活性剂和消毒剂。由于 QAC 生物降解的初始步骤是单加氧，QAC 降解剂需要 O2，但正常曝气会导致严重的泡沫。在这里，我们开发并测试了一种基于氧的膜生物膜反应器 (O2-MBfR)，该反应器通过中空膜壁扩散到积累在膜外表面上的生物膜来输送 O2。即使在 QAC 输入浓度高达 400 mg/L CTAB 的情况下，O2-MBfR 也能维持 QAC 生物降解。无泡氧气转移完全消除了泡沫，生物膜积累有助于 QAC 生物降解剂抵抗毒性。假单胞菌、无色杆菌、窄养单胞菌和黄单胞菌科成员在降解 CTAB 的生物膜群落中占主导地位，它们的比例取决于膜的 O2 输送能力。能够生物降解 QAC 的细菌通常含有抗生素抗性基因 (ARG)，可帮助它们避免 QAC 毒性。在生物膜和液体中检测到 ARGs 的基因拷贝，但液体中的 ARGs 水平比生物膜中的低 5 到 35 倍。总之，O2-MBfR 实现了 CTAB 的有氧生物降解，既没有泡沫也没有毒性，并且还最大限度地减少了 ARGs 的传播。

       Quaternary ammonium compounds (QACs) (for example, cetyltrimethylammonium bromide, CTAB) are emerging pollutants and are widely used as surfactants and disinfectants. Since the initial step of QAC biodegradation is single oxygen addition, QAC degradants require O2, but normal aeration will cause severe foaming. Here, we have developed and tested an oxygen-based membrane biofilm reactor (O2-MBfR), which transports O2 through the diffusion of the hollow membrane wall to the biofilm accumulated on the outer surface of the membrane. Even when the QAC input concentration is as high as 400 mg/L CTAB, O2-MBfR can maintain QAC biodegradation. Foamless oxygen transfer completely eliminates foam, and biofilm accumulation helps QAC biodegradants resist toxicity. Pseudomonas, Achromobacterium, Stenotrophomonas, and Xanthomonas family members dominate the biofilm community that degrades CTAB, and their proportion depends on the O2 transport capacity of the membrane. Bacteria that can biodegrade QAC often contain antibiotic resistance genes (ARG), which can help them avoid QAC toxicity. Gene copies of ARGs were detected in biofilms and fluids, but the levels of ARGs in fluids were 5 to 35 times lower than those in biofilms. In short, O2-MBfR achieves the aerobic biodegradation of CTAB, with neither foam nor toxicity, and also minimizes the spread of ARGs.

https://www.sciencedirect.com/science/article/abs/pii/S0043135417305663