Effect of channel length on water flux and membrane fouling distribution in forward osmosis
- 주제(키워드) Forward Osmosis , Channel length , Dilution and concentration , Organic fouling
- 발행기관 고려대학교 대학원
- 지도교수 홍승관
- 발행년도 2013
- 학위수여년월 2013. 2
- 학위구분 석사
- 학과 일반대학원 건축·사회환경공학과
- 원문페이지 66 p
- 실제URI http://www.dcollection.net/handler/korea/000000038188
- 본문언어 영어
- 제출원본 000045746195
초록/요약
In this study, the flux distribution in a vessel was investigated by performing the flux and fouling tests in forward osmosis (FO). In RO systems, the permeate flux distribution along the vessel is not uniform and the permeate production is declined due to the increase of feed salinity [1]. In FO, the pure water permeates from feed to draw solution due to osmotic pressure; therefore, the draw solution is diluted and the feed solution is concentrated along the channel flows. As a result of dilution of draw solution, it is observed that the permeate flux decreases along the channel length due to decreasing the osmotic pressure difference. And in RO, because the first element processes the largest part of the feed flow, it also retains the largest quantity of the particulate and organic foulants contained in the feed source water [1]. On the other hand, as a result of concentration of feed solution, the more flux decline due to organic fouling is observed at the end module than first module in FO process. Our results suggest that the major factor affecting the extent of fouling in FO is rather the concentration of the feed solution contaminants than the permeate drag force. The fouling reversibility was also examined by increasing cross-flow velocity after the fouling experiments immediately. The permeate flux in the high concentration foulants is not recovered by physical cleaning at the end module, while the cleaning is effective at the 1st module. This result indicates that the high concentration foulants is more adsorbed and interferes with intermolecular interactions on the membrane surface, so the dense fouling layer is formed resulting low cleaning efficiency. Therefore, our results suggest that the water flux and membrane fouling distribution of FO in a vessel are not uniform and they are different with that of RO.
more목차
Introduction 1
Chapter 1. Literature survey 4
1. Forward Osmosis 4
1.1 Basic principle of FO 4
1.2 Advantages of FO 9
1.3 Limitations of FO 12
2. Membrane Fouling 15
2.1 Particulate/Colloidal fouling 17
2.2 Organic fouling 18
2.3 Inorganic fouling 19
2.4 Bio-fouling 20
3. Membrane fouling and flux redistribution of RO 21
Chapter 2. Materials and Methods 24
1. FO membrane 24
2. FO system 24
3. Organic foulant (alginate) 27
4. FO tests with different module length 27
5. Fouling tests with different module length 28
6. Effects of cross-flow directions on flux behavior 28
Chapter 3. Results and discussion 30
1. Flux distribution along the membrane channel 30
2. Membrane fouling distribution along the membrane channel 33
3. Prediction of flux and fouling distribution 35
3.1 Membrane fouling distribution in large scale FO system 35
3.2 Cleaning efficiency in large scale FO system 40
4. Effect of cross-flow directions 44
4.1 Effect of cross-flow directions on flux behavior 44
4.2 Effect of cross-flow directions on fouling behavior 44
Chapter 4. Conclusions 48
Chapter 5. References 49
Chapter 6. Acknowledgement 54
