Kyllönen Hanna, Pirkonen Pentti, Nyström Marianne, Nuortila-Jokinen Jutta, Grönroos Antti
VTT Processes, P.O. Box 1603, FIN-40 101 Jyväskylä, Finland.
Ultrason Sonochem. 2006 May;13(4):295-302. doi: 10.1016/j.ultsonch.2005.04.006. Epub 2005 Jul 6.
Ultrasound based on-line cleaning for membrane filtration of industrial wastewater was studied. An ultrasonic transducer was assembled in the membrane module in order to get an efficient cleaning of membranes in fouling conditions. The focus of the studies was on the effects of the ultrasound propagation direction and frequency as well as the transmembrane pressure. The more open the membrane was the easier the membrane became plugged by wastewater colloids, when the ultrasound propagation direction was from the feed flow side of the membrane. If the membrane was tight enough, the ultrasound irradiated from the feed side of the membrane increased the flux significantly. However, in the circumstances studied, the power intensity needed during filtration was so high that the membranes eroded gradually at some spots of the membrane surface. It was discovered that the ultrasonic field produced by the used transducers was uneven in pressurised conditions. On the other hand, the ultrasound treatment at atmospheric pressure during an intermission pause in filtration turned out to be an efficient and, at the same time, a gentle method in membrane cleaning. The input power of 120 W (power intensity of 1.1 W/cm2) for a few seconds was sufficient for cleaning. The flux improvement was significant when using a frequency of 27 kHz but only minor when using 200 kHz.
对基于超声的工业废水膜过滤在线清洗进行了研究。在膜组件中安装了一个超声换能器，以便在膜污染情况下对膜进行有效清洗。研究重点在于超声传播方向、频率以及跨膜压力的影响。当超声传播方向从膜的进料流侧来时，膜越疏松，就越容易被废水胶体堵塞。如果膜足够致密，从膜的进料侧照射超声会显著提高通量。然而，在所研究的情况下，过滤过程中所需的功率强度过高，以至于膜表面的某些部位会逐渐被侵蚀。研究发现，所用换能器在加压条件下产生的超声场不均匀。另一方面，在过滤间歇期间于大气压下进行超声处理被证明是一种高效且同时温和的膜清洗方法。输入120瓦功率（功率强度为1.1瓦/平方厘米）持续几秒钟就足以进行清洗。使用27千赫频率时通量改善显著，但使用200千赫频率时通量改善较小。
