Correlating TMP Increases with Microbial Characteristics in the Bio-Cake on the Membrane Surface in a Membrane Bioreactor

详细信息    查看全文

• 作者：Byung-Kook Hwang ; Woo-Nyoung Lee ; Kyung-Min Yeon ; Pyung-Kyu Park ; Chung-Hak Lee ; in-Soung Chang ; Anja Drews ; Matthias Kraume
• 刊名：Environmental Science & Technology
• 出版年：2008
• 出版时间：June 1, 2008
• 年：2008
• 卷：42
• 期：11
• 页码：3963 - 3968
• 全文大小：3024K
• 年卷期：v.42,no.11(June 1, 2008)
• ISSN：1520-5851

文摘

Subcritical flux operation is widely practiced in membrane bioreactors (MBRs) to avoid severe membrane fouling and, thus, to maintain sustainable permeability. Filtration at a constant subcritical flux, however, usually leads to a two-stage increase in the transmembrane pressure (TMP): initially slowly, then abruptly. We have investigated the mechanism of this two-stage TMP increase through analyses of the structure and microbial characteristics of the bio-cake formed on the membrane. The MBR was operated under various subcritical and supercritical flux conditions. Under subcritical conditions, we observed the typical two-stage TMP increase. When a constant flux augmented and reached the supercritical conditions, however, the dual TMP change gradually transformed into a steeper, one-stage TMP increase. The second stage TMP increase under the subcritical flux was closely related to the sudden increase in the concentration of extra-cellular polymeric substances (EPSs) at the bottom layer of the bio-cake; we attribute the one-stage TMP increase under the supercritical conditions to the accumulation of microbial flocs and the reduced porosity of the bio-cake under compression. We explain the variation of the EPS concentration in the bio-cake in terms of the spatial and temporal changes of the live-to-dead ratio along the depth of the bio-cake.