Abstract
Reverse osmosis (RO) desalination is a well-established process that removes salt from sea water or brackish water sources. However, scaling by sparingly soluble salts on the membrane surface has been shown to significantly degrade membrane performance. We report the results from a comprehensive study evaluating the effectiveness of flow reversal (FR) controlled by ultrasonic sensors in mitigating scaling during RO desalination. The work utilized a sophisticated multi-port bench-scale flat-sheet cross-flow module with the ability to operate in FR mode with externally mounted ultrasonic sensors. A novel signal-analysis methodology was developed to utilize the ultrasonic waveforms to control a switch in flow direction at the onset of local scaling. Experiments were conducted under controlled conditions with repeated forward-flow (FF) and reverse-flow (RF) cycles. Data from the experiments confirmed that FR controlled by ultrasonic sensors can effectively mitigate scaling on the membrane surface and avoid the expected level of permeate-flow decrease. These results were validated by post-mortem membrane analysis including scalant gravimetric and membrane area-coverage measurements. Overall, the work demonstrates the successful adaptation of ultrasonic sensors for active process control in which the timing of the change in flow direction is critical.
Original language | English |
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Pages (from-to) | 20-32 |
Number of pages | 13 |
Journal | Journal of Membrane Science |
Volume | 419-420 |
DOIs | |
State | Published - 15 Nov 2012 |
Keywords
- Membrane scaling
- Reverse osmosis
- Sensor-controlled flow reversal
- Ultrasonic time-domain reflectometry
ASJC Scopus subject areas
- Biochemistry
- General Materials Science
- Physical and Theoretical Chemistry
- Filtration and Separation