Shandong Provincial Key Laboratory of Water Pollution Control and Resource Reuse, School of Environmental Science and Engineering, Shandong University, Jinan, 250100, China; Institute of Marine Science and Technology, Shandong University, 250000, China.
Shandong Provincial Key Laboratory of Water Pollution Control and Resource Reuse, School of Environmental Science and Engineering, Shandong University, Jinan, 250100, China.
Water Res. 2017 Sep 1;120:190-198. doi: 10.1016/j.watres.2017.04.058. Epub 2017 Apr 26.
Partial nitrification (PN) combined with anaerobic ammonium oxidation process has been recognized as a promising technology for the removal of nitrogenous contaminants from wastewater. This research aimed to investigate the potential of external magnetic field for enhancing the PN process in short and long term laboratory-scale experiments. Different strength magnetic fields (0, 5, 10, 15, 20 and 25 mT) were evaluated in short-term batch tests and 5 mT magnetic field was found to have better ability to increase the activities of aerobic ammonium oxidizing bacteria (AOB) of PN consortium. Long-term effect of magnetic field on PN consortium was studied with 5 mT magnetic field. The results demonstrated that the positive effect of magnetic field on PN process could also be testified at all of the four stages. Furthermore, a decrease of bacterial diversity was noted with the increase of magnetic field strength. Relative abundance of Nitrosomonadaceae decreased significantly (p < 0.01) from 13.9% in R to 12.9% in R and 5.5% in R. Functional genes forecast based on KEGG database indicated that the expressions of functional genes related to signal transduction and cell motility in 5 mT environment were higher expressed compared with no magnetic field addition and high magnetic field addition. The existence of 5 mT magnetic field didn't increase the abundance of AOB but increased the activity of AOB by increasing the rate of free ammonia into the interior of microbial cells. Addition of magnetic field couldn't change the final state of PN process according to the hypothesis proposed in this article. These findings indicated that the weak magnetic field was useful and reliable for the fast start-up of PN process since it was proved as a simple and convenient approach to enhance AOB activity.
短程和长期实验室规模实验均证实，部分硝化（PN）联合厌氧氨氧化工艺是去除废水中含氮污染物的一种很有前途的技术。本研究旨在探讨外加磁场对强化 PN 过程的潜力，实验采用短期批处理实验评估了不同强度的磁场（0、5、10、15、20 和 25 mT），结果发现 5 mT 磁场更有利于提高 PN 联合体中好氧氨氧化菌（AOB）的活性。进一步研究了磁场对 PN 联合体的长期影响，采用 5 mT 磁场。结果表明，磁场对 PN 过程的积极影响在所有四个阶段都能得到证明。此外，随着磁场强度的增加，细菌多样性呈下降趋势。与对照相比，Nitrosomonadaceae 的相对丰度在磁场处理组 R、R 和 R 中分别显著降低（p < 0.01），从 13.9%降至 12.9%和 5.5%。基于 KEGG 数据库预测的功能基因表明，与信号转导和细胞运动相关的功能基因在 5 mT 环境中的表达高于无磁场添加和高磁场添加组。5 mT 磁场的存在并没有增加 AOB 的丰度，而是通过增加游离氨进入微生物细胞内部的速率来提高 AOB 的活性。根据本文提出的假设，外加磁场并没有改变 PN 过程的最终状态。这些发现表明，弱磁场对于 PN 过程的快速启动是有用且可靠的，因为它被证明是一种增强 AOB 活性的简单方便的方法。
