水力条件对反应器内生物膜的生长及流态形式起着决定性作用。实验分别用0.15,0.25,0.35 m/s的水流流速对内径为44 mm的管状生物膜反应器进行水力冲击,观察不同生物滤料的挂膜情况,并利用计算流体力学软件对导流式移动床生物膜反应器流态进行数值模拟。结果显示,在低流速的水力冲击下,生物滤料的挂膜效果最好,平均厚度约为70 μm,且不同结构生物滤料的挂膜情况无明显差异;反应器的模拟曝气速度为0.6 m/s时,其内部的综合流动及挂膜效果最佳。因此可知,生物膜的生长情况与同种材质生物滤料的结构形状无关,但与滤料所处的水力情况有关,膜厚度随着水流速度的增大而减小;移动床生物膜反应器的曝气量大小及结构形状是影响其流态的重要因素。本研究可以为此类反应器的设计与高效运行提供基础数据。

With the development of aquaculture industry and the community’s increasing attention to environmental protection,aquaculture wastewater reuse has become an inevitable trend.As a key factor in aquaculture wastewater treatment,hydraulic condition plays critical roles in biofilm growth and water flow pattern within the reactors.Researching the relationship between biofilm growth and water flow pattern will be conducive to improve the efficiency of wastewater treatment.In the present study,aiming to know the effect of flow velocity on biofilm growth,four types of polyethylene(PE)biofilm carriers and twelve tubular biofilm reactors with a diameter of 44 mm which were made of acrylic material were chosen.Each kind of the biofilm carrier was enclosed into three tubular biofilm reactors and lashed with flow velocity of 0.15 m/s,0.25 m/s,0.35 m/s,respectively,the biofilm carrier’s loading height was 40 mm,flow velocity was controlled by plastic flowmeters and the pipe connection used polyvinyl chloride(PVC)pipes and transparent plastic hose.In order to avoid suspended solids(TSS)in aquaculture wastewater having an impact on the experimental results,this study used artificial water,the concentration of NH₄-N was 2 mg/L,DO was 6-9 mg/L and pH was 7-8.At the same time,the flow pattern of Diversion Moving Bed Biofilm Reactor was simulated by Computational Fluid Dynamic software to observe the state of water flow at different aeration rates.After sixty days,the biofilm thickness of different types of biofilm carriers in different flow velocity were observed with electron microscope.The result showed that the biofilm thickness decreased with the increasing of flow velocity,the thickest biofilm with the thickness of 70 μm occurred at the lowest velocity of 0.15 m/s and the thinnest biofilm with the thickness of 20 μm occurred at the highest velocity of 0.35 m/s.There were no significant differences in biofilm thickness among different structures of biofilm carriers.When the simulation of aeration rate of reactor was set at 0.6 m/s,its integrated flow pattern and biofilm growth situation were the best,the flow velocity in downflow area was 0.06-0.12 m/s and in upflow area was 0.24-0.3 m/s,the eddy area accounted for 10%.The data indicated that the hydraulic condition rather than the structures of biofilm carriers with same material was related to biofilm growth,and low flow velocity is favorable for biofilm growth.Besides,the aeration intensity and reactor’s structure are important factors affecting the Diversion Moving Bed Biofilm Reactor’s flow pattern.This study provided basic data about design and operation for such reactors,and it could be very practical to use the method of combination of experiment and simulation to study biofilm growth and flow pattern,and the data and the method could also be applied to a variety of fields.

国家鲆鲽类产业体系项目(nycytx-50-G04);公益性行业(农业)科研专项(nyhyzx07-046-鲆鲽工程化);农业部“引进国际先进科学技术”自由申报项目(2008-Z9)