DTU Environment, Department of Environmental Engineering, Technical University of Denmark, Miljoevej, Building 113, 2800 Kgs. Lyngby, Denmark.
Water Res. 2012 Jul;46(11):3516-24. doi: 10.1016/j.watres.2012.03.053. Epub 2012 Apr 1.
Total ammonia nitrogen (TAN) removal by microbial nitrification is an essential process in recirculating aquaculture systems (RAS). In order to protect the aquatic environment and fish health, it is important to be able to predict the nitrification rates in RAS's. The aim of this study was to determine the impact of hydraulic film diffusion on the nitrification rate in a submerged biofilter. Using an experimental batch reactor setup with recirculation, active nitrifying biofilter units from a RAS were exposed to a range of hydraulic flow velocities. Corresponding nitrification rates were measured following ammonium chloride, NH₄Cl, spikes and the impact of hydraulic film diffusion was quantified. The nitrification performance of the tested biofilter could be significantly increased by increasing the hydraulic flow velocity in the filter. Area based first order nitrification rate constants ranged from 0.065 m d⁻¹ to 0.192 m d⁻¹ for flow velocities between 2.5 m h⁻¹ and 40 m h⁻¹ (18 °C). This study documents that hydraulic film diffusion may have a significant impact on the nitrification rate in fixed film biofilters with geometry and hydraulic flows corresponding to our experimental RAS biofilters. The results may thus have practical implications in relation to the design, operational strategy of RAS biofilters and how to optimize TAN removal in fixed film biofilter systems.
总氨氮（TAN）的微生物硝化去除是循环水产养殖系统（RAS）中的一个重要过程。为了保护水生环境和鱼类健康，能够预测 RAS 中的硝化速率非常重要。本研究旨在确定水力膜扩散对浸没式生物滤池硝化速率的影响。使用带有循环的实验批处理反应器设置，将来自 RAS 的活性硝化生物滤池单元暴露于一系列水力流速下。在添加氯化铵、NH₄Cl 后测量相应的硝化速率，并量化水力膜扩散的影响。通过增加过滤器中的水力流速，可以显著提高测试生物滤池的硝化性能。水力流速在 2.5 m h⁻¹ 至 40 m h⁻¹（18°C）之间时，基于面积的一级硝化速率常数范围为 0.065 m d⁻¹ 至 0.192 m d⁻¹。本研究记录了水力膜扩散可能对与我们的实验 RAS 生物滤池几何形状和水力流动相对应的固定膜生物滤器中的硝化速率产生重大影响。因此，这些结果可能对 RAS 生物滤池的设计、操作策略以及如何优化固定膜生物滤器系统中的 TAN 去除具有实际意义。
