Laboratory for Wastewater Management and Treatment Technologies, Department of Environmental Engineering, Democritus University of Thrace, 671 00 Xanthi, Greece.
Bioprocess Biosyst Eng. 2010 Feb;33(2):293-8. doi: 10.1007/s00449-009-0396-8. Epub 2009 Dec 3.
Aerated channel reactors with a uniform field of aeration may display flow stratification and short-circuit phenomena in wastewater treatment systems. In this study, we present data suggesting that flow stratification is closely related to the aeration rate and the arrangement of aerators. A full-scale oxidation ditch, with a total volume of 6,500 m(3) and a membrane-diffused aerated zone of 60 x 7 x 5 m (length-width-depth), was selected for water velocity measurements. Two profiles of the oxidation ditch were studied in detail: the first one was at the end of the aerated zone and the second one at the end of the anoxic zone. The results of this work demonstrate that the horizontal water velocity at the end of the aerated zone displayed significant stratification, with maximum velocity near the water surface (0.5-0.7 m/s) and almost zero velocity at a depth of 2.5 m. At the end of the anoxic zone, water velocity was uniform and equal to 0.27-0.31 m/s. Increasing the aeration rate from 1,800 to 4,300 m(3)/h, almost 90% of the water flow was found to discharge through the upper-half of the channel reactor profile. Different options to mitigate flow stratification of the oxidation ditch are discussed in this paper.
在废水处理系统中，充氧沟道反应器具有均匀的充气场，但可能会出现水流分层和短路现象。本研究提供的数据表明，水流分层与充气率和曝气器布置密切相关。本研究选择了一个总容积为 6500 立方米、膜扩散曝气区为 60x7x5 米（长x宽x深）的全尺寸氧化沟，用于测量水流速度。详细研究了氧化沟的两个剖面：第一个剖面位于充气区末端，第二个剖面位于缺氧区末端。研究结果表明，充气区末端的水平水流速度存在明显的分层现象，水面附近的最大速度接近 0.5-0.7 米/秒，而在 2.5 米深处几乎为零。在缺氧区末端，水流速度均匀，等于 0.27-0.31 米/秒。当曝气率从 1800 立方米/小时增加到 4300 立方米/小时时，发现近 90%的水流通过沟道反应器剖面的上半部分排出。本文讨论了减轻氧化沟水流分层的不同选择方案。
