Wang Shu-mei, Liu Jun-xin
Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China.
J Environ Sci (China). 2005;17(6):894-8.
Compared to conventional oxidation ditches, an integrated oxidation ditch with vertical circle (IODVC) has the characters of concise configuration, simple operation and maintenance, land saving and automatical sludge returning. By the utilization of vertical circulation, an aerobic zone and an anoxic zone can be unaffectedly formed in the IODVC. Therefore, COD and nitrogen can be efficiently removed. However, the removal efficiency of phosphorus was low in the IODVC. In the experiment described, a laboratory scale system to add an anaerobic column to the IODVC has been tested to investigate the removal of phosphorus from wastewater. The experimental results showed that the removal efficiency of TP with the anaerobic column was increased to 54.0% from 22.3% without the anaerobic column. After the acetic sodium was added into the influent as carbon sources, the mean TP removal efficency of 77.5% was obtained. At the same time, the mean removal efficiencies of COD, TN and NH3-N were 92.2%, 81.6% and 98.1%, respectively, at 12 h of HRT and 21-25 d of SRT. The optimal operational conditions in this study were as follows: recycle rate = 1.5-2.0, COD/TN > 6, COD/TP > 40, COD loading rate = 0.26-0.32 kgCOD/(kgSS x d), TN loading rate = 0.028-0.034 kgTN/(kgSS x d) and TP loading rate = 0.003-0.005 kgTP/(kgSS x d), respectively.
与传统氧化沟相比，竖流式一体化氧化沟（IODVC）具有结构简洁、运行维护简单、节省土地和污泥自动回流等特点。通过利用竖向循环，在竖流式一体化氧化沟中可不受影响地形成好氧区和缺氧区。因此，COD和氮能够被高效去除。然而，竖流式一体化氧化沟中磷的去除效率较低。在所描述的实验中，已测试了一个在竖流式一体化氧化沟中添加厌氧柱的实验室规模系统，以研究废水中磷的去除情况。实验结果表明，有厌氧柱时TP的去除效率从无厌氧柱时的22.3%提高到了54.0%。在向进水添加乙酸钠作为碳源后，获得了平均77.5%的TP去除效率。同时，在水力停留时间为12 h和污泥停留时间为21 - 25 d时，COD、TN和NH₃-N的平均去除效率分别为92.2%、81.6%和98.1%。本研究中的最佳运行条件如下：回流比 = 1.5 - 2.0，COD/TN > 6，COD/TP > 40，COD负荷率 = 0.26 - 0.32 kgCOD/(kgSS·d)，TN负荷率 = 0.028 - 0.034 kgTN/(kgSS·d)，TP负荷率 = 0.003 - 0.005 kgTP/(kgSS·d)。
