du Toit G J G, Ramphao M C, Parco V, Wentzel M C, Ekama G A
Water Research Group, University of Cape Town, 7700, RSA, South Africa.
Water Sci Technol. 2007;56(6):105-13. doi: 10.2166/wst.2007.643.
The use of immersed membranes for solid-liquid separation in biological nutrient removal activated sludge (BNRAS) systems was investigated at lab scale. Two laboratory-scale BNR activated sludge systems were run in parallel, one a MBR system and the other a conventional system with secondary settling tanks. Both systems were in 3 reactor anaerobic, anoxic, aerobic UCT configurations. The systems were set up to have, as far as possible, identical design parameters such as reactor mass fractions, recycles and sludge age. Differences were the influent flow and total reactor volumes, and the higher reactor concentrations in the MBR system. The performances of the two systems were extensively monitored and compared to identify and quantify the influence of the membranes on system response. The MBR UCT system exhibited COD, FSA, TKN, TP and TSS removals that were consistently equivalent or superior to the conventional system. Better P removal in the MBR was attributed to lower observed P uptake in the anoxic zone. High nitrate loads to the anoxic reactor appeared to be the determining factor in stimulating P uptake. The MBR UCT system had a greater sludge production than the conventional system. This was partly attributable to the retention of all solids in the MBR reactor. For steady state design this increase is accommodated by increasing the influent unbiodegradable particulate COD fraction. Additionally an attempt was made to determine the Alpha values in the oxygen transfer rate. This paper briefly summarises and compares the results from both systems, and the conclusions that can be drawn from these results.
在实验室规模下，研究了浸没式膜在生物营养物去除活性污泥（BNRAS）系统中用于固液分离的情况。两个实验室规模的BNR活性污泥系统并行运行，一个是膜生物反应器（MBR）系统，另一个是带有二次沉淀池的传统系统。两个系统均采用厌氧、缺氧、好氧的三反应器UCT构型。这些系统在设计参数上尽可能保持一致，如反应器质量分数、回流比和污泥龄。不同之处在于进水流量和总反应器体积，以及MBR系统中较高的反应器浓度。对这两个系统的性能进行了广泛监测和比较，以确定并量化膜对系统响应的影响。MBR UCT系统在化学需氧量（COD）、易生物降解物质（FSA）、总凯氏氮（TKN）、总磷（TP）和总悬浮固体（TSS）的去除方面始终等同于或优于传统系统。MBR系统中更好的磷去除归因于缺氧区观察到的较低的磷吸收量。进入缺氧反应器的高硝酸盐负荷似乎是刺激磷吸收的决定性因素。MBR UCT系统的污泥产量高于传统系统。这部分归因于MBR反应器中所有固体的截留。对于稳态设计，这种增加通过提高进水不可生物降解颗粒COD的比例来适应。此外，还尝试确定氧传递速率中的α值。本文简要总结并比较了两个系统的结果以及从这些结果中可以得出的结论。
