一体式膜-生物反应器中膜污染过程的动态分析

Dynamic analysis of the membrane fouling process in a submerged membrane bioreactor

膜污染过程的动态研究对于有效地控制膜污染意义重大。结合膜过滤压差的上升和污染膜表面微观形态的变化 ,对不同污泥浓度和膜通量条件下 ,一体式膜 生物反应器中膜污染过程进行了动态分析。结果表明 ,膜污染初期主要是水中溶解性物质在膜表面附着 ,随后污泥在膜表面沉积。溶解性有机物在膜面的附着 ,对膜过滤压差即膜过滤阻力的变化影响不大 ,而活性污泥在膜表面的大量沉积将导致膜过滤压差迅速上升。污泥浓度愈高 ,膜通量愈大时 ,活性污泥颗粒愈易在膜面沉积。通过停止进出水维持空曝气、降低反应器内污泥浓度或延长膜的停抽时间可以使沉积在膜表面的悬浮污泥脱离膜表面 ,从而使膜过滤能力得到很好的恢复。采用经典的膜污染模型对各运行阶段膜污染模式进行了分析 ,模型拟合结果与电镜观察结果基本吻合。

Dynamic analysis of the fouling process is very important for effective control of membrane fouling. Under different sludge concentrations and fluxes, the changes of transmembrane pressure, combined with changes of the appearances of the fouled membrane surface were investigated, to dynamically analyze membrane fouling process of a submerged membrane bioreactor. It was found that soluble organic substances were adsorbed on the membrane surface at the early stage of membrane fouling, then the sludge particles deposited on it. Soluble organic foulants contributed little but sludge particles deposited on the membrane surface resulted in a rapid increase of the transmembrane pressure. The higher the sludge concentration and the flux were, the easier it was for the sludge particles to deposit on the membrane surface. The sludge cake layer was reversibly removed through extended aeration without effluent, reduced sludge concentration or prolonged cease time of membrane filtration. Traditional membrane fouling models were applied to analyze the membrane fouling processes, which was consistent with the results of SEM.