The Centrifugal Membrane and Density Separation (CMDS) process is a novel type of membrane process that exploits the action of a centrifuge to generate process pressure for reverse osmosis and nanofiltration. The centrifuge could potentially enhance flux and alleviate fouling of the membrane as a result of the hydrodynamic environment of the centrifuge. All experimental work has been conducted on a prototype model of the CMDS process. The apparatus allows a membrane module to be fixed in space at a specified orientation, with respect to the rotation. This orientation in space is denoted by the terms “pitch, roll and yaw” (p,r,y).
Experiments have been done using brine feed solutions at various concentrations to determine if the CMDS process minimizes the effects of concentration polarization. An example of this was illustrated with a 54% flux enhancement relative to a conventional membrane process using a 35000 ppm NaCl feed solution. Colloidal feed solutions were also used to examine how the CMDS process enhances flux in a fouling environment. These feed solutions include 21 g/L silica and 300 mg/L humic acid, with typical relative flux enhancement factors (κ) found to be 0.59 and 0.14, respectively. The final group of experiments examined the use of 50 g/L whey feed solutions with nanofiltration membranes. Results obtained here indicate that the centrifugal action enhanced the flux with an absolute flux enhancement factor (κ′) of 17.5 L/m² hr. These experiments have shown that a given orientation (90,270,0) best enhances the flux of a membrane with respect to colloidal fouling, while showing that another orientation (90,180,0) best reduces the effects of concentration polarization.
Scanning electron microscopy (SEM) and an energy dispersive x-ray (EDX) detector have helped to examine the nature of the fouling layers and determine how well the layers adhere to the surface of the membrane. It was determined that in some cases, the fouling layer adhered better to the surface of a membrane used in the CMDS process. However, as the fluxes were typically higher in the dynamic process, it leads to the conclusion that the fouling layer on the CMDS membranes is more permeable.
From the experimental work it has been concluded that the forces at work in the CMDS process create sufficient secondary flow instabilities to reduce the effects of fouling and concentration polarization on the membrane surface. The significance of this process with respect to industrial applications is considered, and the process is deemed feasible for such applications. / Graduate
| Identifer | oai:union.ndltd.org:uvic.ca/oai:dspace.library.uvic.ca:1828/8958 |
| Date | 08 January 2018 |
| Creators | Lycon, David Steven |
| Contributors | Fyles, Thomas M., Vickers, G. W. |
| Source Sets | University of Victoria |
| Language | English, English |
| Detected Language | English |
| Type | Thesis |
| Format | application/pdf |
| Rights | Available to the World Wide Web |
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