Chang I S, Judd S J
Dept. of Environmental Engineering, Hoseo University, Asan, 336-795, South Korea.
Water Sci Technol. 2003;47(12):149-54.
The air sparging technique has been recognised as an effective way to control membrane fouling. However, its application to a submerged MBR (Membrane Bio-Reactor) has not yet been reported. This paper deals with the performances of air sparging on a submerged MBR for wastewater treatment. Two kinds of air sparging techniques were used respectively. First, air is injected into the membrane tube channels so that mixed liquor can circulate in the bioreactor (air-lift mode). Second, a periodic air-jet into the membrane tube is introduced (air-jet mode). Their applicability was evaluated with a series of lab-scale experiments using domestic wastewater. The flux increased from 23 to 33 l m(-2) h(-1) (43% enhancement) when air was injected for the air-lift module. But further increase of flux was not observed as the gas flow increased. The Rc/(Rc+Rf), ratio of cake resistance (Rc) to sum of Rc and Rf (internal fouling resistance), was 23%, indicating that the Rc is not the predominant resistance unlike other MBR studies. It showed that the cake layer was removed sufficiently due to the air injection. Thus, an increase of airflow could not affect the flux performance. The air-jet module suffered from a clogging problem with accumulated sludge inside the lumen. Because the air-jet module has characteristics of dead end filtration, a periodic air-jet was not enough to blast all the accumulated sludge out. But flux was greater than in the air-lift module if the clogging was prevented by an appropriate cleaning regime such as periodical backwashing.
空气曝气技术已被公认为控制膜污染的有效方法。然而，其在浸没式膜生物反应器（MBR）中的应用尚未见报道。本文探讨了空气曝气对浸没式MBR处理废水性能的影响。分别采用了两种空气曝气技术。第一种，将空气注入膜管通道，使混合液在生物反应器中循环（气提模式）。第二种，采用周期性空气喷射进入膜管（空气喷射模式）。通过一系列使用生活污水的实验室规模实验对它们的适用性进行了评估。对于气提模块，当注入空气时，通量从23升·平方米⁻²·小时⁻¹增加到33升·平方米⁻²·小时⁻¹（提高了43%）。但随着气体流量增加，通量未进一步增加。滤饼阻力（Rc）与Rc和Rf（内部污染阻力）之和的比值Rc/(Rc+Rf)为23%，这表明与其他MBR研究不同，Rc不是主要阻力。结果表明，由于空气注入，滤饼层被充分去除。因此，气流增加不会影响通量性能。空气喷射模块存在膜腔内污泥堆积导致的堵塞问题。由于空气喷射模块具有死端过滤的特点，周期性空气喷射不足以将所有堆积的污泥冲出。但如果通过适当的清洗方式（如定期反冲洗）防止堵塞，通量会比气提模块更大。
