Membrane Fouling during Constant Flux Crossflow Microfiltration of Dilute Suspensions of Active Dry Yeast

Anaerobic membrane bioreactors (AnMBRs) have aroused growing interest in wastewater treatment and energy recovery. However, serious membrane fouling remains a critical hindrance to AnMBRs. Here, a novel membrane fouling mitigation via optimizing initial water flux is proposed, and its feasibility was evaluated by comparing the membrane performance in AnMBRs between constant flux and varying flux modes. Results indicated that, compared with the constant flux mode, varying flux mode significantly prolonged the membrane operating time by mitigating membrane fouling. Through the analyses of fouled membranes under two operating modes, the mechanism of membrane fouling mitigation was revealed as follows: A low water flux was applied in stage 1 which slowed down the interaction between foulants and membrane surface, especially reduced the deposition of proteins on the membrane surface and formed a thin and loose fouling layer. Correspondingly, the interaction between foulants was weakened in the following stage 2 with a high water flux and, subsequently, the foulants absorbed on the membrane surface was further reduced. In addition, flux operating mode had no impact on the contaminant removal in an AnMBR. This study provides a new way of improving membrane performance in AnMBRs via a varying flux operating mode.

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Improvement of microfiltration performance in water treatment: is critical flux a viable solution?

Water Science & Technology ◽

10.2166/wst.2000.0669 ◽

2000 ◽

Vol 41 (10-11) ◽

pp. 309-315 ◽

Cited By ~ 5

Author(s):

S. Vigneswaran ◽

D.Y. Kwon ◽

H.H. Ngo ◽

J.Y. Hu

Keyword(s):

Membrane Fouling ◽

Particle Deposition ◽

Material Balance ◽

Transmembrane Pressure ◽

Operational Mode ◽

Permeate Flux ◽

Critical Flux ◽

Viable Solution ◽

Crossflow Microfiltration

In this study, three definitions for critical flux were introduced based on the crossflow microfiltration (CFMF) experiments conducted under an operational mode of constant permeate flux. The critical flux based on material balance was calculated from the rate of particles deposition. The highest permeate flux results in no particle deposition being taken at the critical flux. The second definition was based on the increase in transmembrane pressure (TMP). The critical flux based on the TMP increase is the flux below which the membrane fouling does not occur. The third definition was based on the direct observation of particles deposition through microscope. Detailed experiments were conducted with synthetic suspension of different sizes of latex particles. Long term experiments conducted with polydispersed kaolin clay suspension indicated that the critical flux based on material balance concept is more realistic in field conditions.

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Membrane fouling during constant flux filtration in membrane bioreactors

Membrane Technology ◽

10.1016/s0958-2118(02)07018-0 ◽

2002 ◽

Vol 2002 (7) ◽

pp. 6-10 ◽

Cited By ~ 39

Author(s):

S. Ognier ◽

C. Wisniewski ◽

A. Grasmick

Keyword(s):

Membrane Fouling ◽

Membrane Bioreactors ◽

Constant Flux

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Membrane fouling prevention in crossflow microfiltration by the use of electric fields

Chemical Engineering Science ◽

10.1016/0009-2509(87)80042-8 ◽

1987 ◽

Vol 42 (4) ◽

pp. 829-842 ◽

Cited By ~ 52

Author(s):

R.J. Wakeman ◽

E.S. Tarleton

Keyword(s):

Electric Fields ◽

Membrane Fouling ◽

Crossflow Microfiltration

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Bench-scale study of ultrafiltration membranes for evaluating membrane performance in surface water treatment

Water Quality Research Journal ◽

10.2166/wqrjc.2016.039 ◽

2016 ◽

Vol 51 (2) ◽

pp. 128-140 ◽

Cited By ~ 1

Author(s):

Dillon A. Waterman ◽

Steven Walker ◽

Bingjie Xu ◽

Roberto M. Narbaitz

Keyword(s):

Hollow Fiber ◽

Membrane Fouling ◽

Organic Matter Content ◽

Operating Conditions ◽

Cycle Duration ◽

Operational Parameters ◽

Constant Flux ◽

Bench Scale ◽

Membrane Performance ◽

The Impact

Currently, there is no standard bench-scale dead-end ultrafiltration (UF) testing system. The aim of the present study was to design and build a bench-scale hollow fiber UF system to assess the impact of operational parameters on membrane performance and fouling. A bench-scale hollow fiber UF system was built to operate at a constant flux (±2% of the set-point flux) and included automated backwash cycles. The development of the bench-scale system showed that it is very difficult to maintain a constant flux during the first minute of the filtration cycles, that digital flow meters are problematic, and that the volume of the backwash waste lines should be minimized. The system was evaluated with Ottawa River water, which has a relatively high hydrophobic natural organic matter content and is typical of Northern Canadian waters. The testing using different permeate fluxes, filtration cycle duration and backwash cycle duration showed that this system mimics the performance of larger systems and may be used to assess the impact of operating conditions on membrane fouling and alternative pretreatment options. Modeling the first, middle, and last filtration cycles of the six runs using single and dual blocking mechanisms yielded inconsistent results regarding the controlling fouling mechanisms.

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