Abstract:

It is significant to understand the mechanism of operating conditions on the treatment efficiency of biological aerated filter (BAF). In this study, fiber Bragg grating (FBG) was used to monitor the shear-force distribution in BAF in situ. The effects of hydraulic retention time (HRT) and air-water ratio (A/L) on the internal flow field distribution characteristics of BAF were simulated by CFD. The results show that the increase of shear force promotes the renewal metabolism of biofilm. When HRT is 8 h and A/L is 10∶1, the amount of biofilm/shear force (M/S) is 0.17, and the effect of BAF on COD and $\mathrm{N}{\mathrm{H}}_{\mathrm{4}}^{+}$-N removal rate reached 86.58% and 82.17%, respectively. The results indicate that the appropriate shear-force inside the BAF promotes the renewal and metabolism of the biofilm and improves the operating efficiency of the reactor. Therefore, this study explored the effect of shear on the reactor operational performance by M/S and provided a theoretical basis for subsequent optimization of the reactor.

Key words: biological aerated filter, numerical simulation, fiber Bragg grating, biofilm, shear-force distribution, fluid mechanics

摘要：

了解曝气生物滤池(biological aerated filter， BAF)中运行条件变化对反应器处理效率的影响机制具有重要意义。采用光纤布拉格光栅(fiber Bragg grating， FBG)对BAF中剪切力分布进行了原位监测。同时，借助CFD模拟计算了水力停留时间(HRT)和气水比(A/L)对BAF内部流场分布特性的影响。实验表明，剪切力的增加促进了生物膜的更新代谢，当HRT为8 h、A/L为10∶1时，生物膜量/剪切力(M/S)为0.17，BAF对COD和$\mathrm{N}{\mathrm{H}}_{\mathrm{4}}^{+}$-N的去除率分别达到86.58%和82.17%。结果表明BAF内部适宜的剪切力促进了生物膜的更新代谢，提高了反应器的运行效率。因此，利用M/S探讨了剪切力对反应器运行性能的影响，可为反应器后续的优化提供理论基础。

关键词: 曝气生物滤池, 数值模拟, 光纤布拉格光栅, 生物膜, 剪切力分布, 流体力学