State Key Laboratory of Pollution Control and Resources Reuse, Shanghai Institute of Pollution Control and Ecological Security, College of Environmental Science and Engineering, Tongji University, Siping Road, Shanghai, 200092, PR China.
State Key Laboratory of Pollution Control and Resources Reuse, Shanghai Institute of Pollution Control and Ecological Security, College of Environmental Science and Engineering, Tongji University, Siping Road, Shanghai, 200092, PR China.
Water Res. 2019 Apr 15;153:284-294. doi: 10.1016/j.watres.2019.01.029. Epub 2019 Jan 30.
As obligate anaerobes, anammox bacteria are sensitive to oxygen, which might hinder the maximization of anammox activity. However, there are very few effective strategies to rapidly recover anammox activity after its deterioration under exposure of oxygen. In this study, the activity recovery of anammox bacteria encountering dissolved oxygen (DO) exposure (0.2 and 2.0 mg L) were compared by three strategies in short-term experiments, nZVI, Fe(II) dosing, and N purging. nZVI is more effective in recovering anammox activity with a high DO exposure (2 mg L), compared to a low DO exposure (0.2 mg L). After inhibiting by 2.0 mg L DO, anammox activity recovery (normalized to the control) was ranked in the order of nZVI (5 mg L) addition (63 ± 8.2%) > Fe(II) (5 mg L) addition (41 ± 8.0%) >N purging (39 ± 4.0%). In contrast to Fe(II) ion additions, the shell structure of nZVI combined with the buffering effect of biomass-extracellular polysaccharide (EPS) prevented the sharp pH variation and excessive dissolved Fe(II)/Fe(III) in solution. Under such circumstances, nZVI addition (5 and 25 mg L) increased the intracellular reactive oxygen species (ROS) to a moderate level (<200%), which might be responsible for the better activity recovery of anammox than that of Fe(II) addition and N purging. Specifically, 5 mg L nZVI dosage moderately enhanced the intracellular O production (∼150% of the control) after scavenging 2.0 mg L DO, and the anammox activity recovered better than that of both 5 and 25 mg L Fe(II) ions additions. However, high dosage nZVI (75 mg L) inhibited anammox activity in spite of low or high DO exposure. Our findings elucidate that appropriate amount of nZVI (short-term dosing) can rapidly recover anammox activity when anammox bacteria encountering oxygen exposure accidentally and could be useful in facilitating the robust operation of anammox-based processes.
作为严格的厌氧菌，厌氧氨氧化菌对氧气敏感，这可能会阻碍厌氧氨氧化活性的最大化。然而，在接触氧气后，厌氧氨氧化菌的活性恶化，目前很少有有效的策略能快速恢复其活性。在这项研究中，通过短期实验比较了三种策略（纳米零价铁（nZVI）、Fe(II)投加和氮气吹扫）在应对溶解氧（DO）暴露（0.2 和 2.0mg/L）时对厌氧氨氧化菌活性恢复的效果。与低 DO 暴露（0.2mg/L）相比，nZVI 在高 DO 暴露（2mg/L）下更有效地恢复厌氧氨氧化活性。在 2.0mg/L DO 抑制后，按归一化到对照组的顺序，厌氧氨氧化活性恢复（nZVI（5mg/L）添加（63±8.2%）>Fe(II)（5mg/L）添加（41±8.0%）>氮气吹扫（39±4.0%））。与 Fe(II)离子添加相比，nZVI 的壳结构结合生物量-胞外多糖（EPS）的缓冲作用防止了溶液中 pH 值的急剧变化和溶解的 Fe(II)/Fe(III)的过度增加。在这种情况下，nZVI 添加（5 和 25mg/L）将细胞内活性氧（ROS）增加到适度水平（<200%），这可能是 nZVI 添加比 Fe(II)添加和氮气吹扫更能恢复厌氧氨氧化活性的原因。具体而言，在清除 2.0mg/L DO 后，5mg/L nZVI 剂量适度增加了细胞内的 O 生成（比对照组高约 150%），并且厌氧氨氧化活性的恢复优于 5 和 25mg/L Fe(II)离子添加。然而，高剂量 nZVI（75mg/L）抑制了厌氧氨氧化菌的活性，无论 DO 暴露水平高低都是如此。我们的研究结果表明，当厌氧氨氧化菌意外接触氧气时，适量的 nZVI（短期投加）可以快速恢复其活性，这对于促进基于厌氧氨氧化的工艺的稳健运行可能是有用的。
