长泥龄膜生物反应器中活性污泥的膜污染研究
Study on membrane fouling caused by activated sludge from a membrane bioreactor with long solid retention time
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摘要: 长泥龄膜生物反应器(MBR)内污泥性质与普通活性污泥有显著差异。利用一污泥停留时间长达300 d的膜生物反应器研究了污泥浓度、过膜压力和错流速率对长泥龄活性污泥膜污染特性的影响。研究结果表明,使用0.2 μm微滤膜错流过滤时,浓差极化阻力Rcp和滤饼层阻力Rc是膜污染的主要影响因素,各占总的膜阻力Rt的23%~63%和31%~73%。与之相比,膜内部阻力Rif和膜固有的阻力Rm只占总的膜阻力Rt的0.7%~2.4%和1.2%~6.4%,几乎可以忽略不计。随着污泥浓度,过膜压力的增大和错流速率的减小,膜污染逐渐加剧。因此,降低过膜压力,提高流速,可以有效减缓膜污染,减少清洗频率,延长膜组件的使用寿命,从而节约操作成本,推广应用。Abstract: The effects of MLSS concentration, transmembrane pressure (TMP) and crossflow velocity (CFV) on the membrane fouling caused by activated sludge taken from a membrane bioreactor (MBR) with 300 day solid retention time (SRT) were studied. The characteristics of this activated sludge varied a lot from the conventional activated sludge. It was revealed that concentration polarization layer resistance Rcp and cake layer resistance Rc were dominant contributors to total resistance Rt during the cross-flow filtration of using a MF membrane with pore size of 0.2 μm,and their relative contributions to total resistance Rt were 23%~63% and 31%~73% respectively. On the other hand, internal fouling resistance Rif and intrinsic membrane resistance Rm were negligible compared with Rcp and Rc, with 0.7%~2.4% and 1.2%~6.4% relative contributions to total resistance Rt respectively. Moreover, the membrane fouling resistance increased with increasing MLSS concentration, TMP and decreasing CFV. Therefore,membrane fouling can be controlled effectively with decreasing TMP and increasing CFV. Lower cleaning frequency and longer membrane life would be achieved, resulting in lower operation cost and wider application of MBRs with long SRTs.
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Key words:
- long SRT /
- membrane bioreactor /
- membrane fouling /
- fouling resistance
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