Investigation of fouling behavior in forward osmosis (FO) for seawater desalination and wastewater reclamation
- 주제(키워드) Forward Osmosis , Fouling , Seawater Desalination , Wastewater Reclamation
- 발행기관 고려대학교 대학원
- 지도교수 홍승관
- 발행년도 2011
- 학위수여년월 2011. 2
- 학위구분 석사
- 학과 일반대학원 건축·사회환경공학과
- 세부전공 환경공학
- 원문페이지 79 p
- 실제URI http://www.dcollection.net/handler/korea/000000025510
- 본문언어 영어
- 제출원본 000045641240
초록/요약
In the FO process, highly concentrated draw solution is placed opposite to the feed solution with a semi-permeable membrane being placed in between.To induce osmotic pressure gradient between the feed and draw solutions, either count or co-current channel flow is developed. Because of this operational peculiarity, water flows feed to draw side; however, the draw solutes move draw to feed side, simultaneously. The phenomenon of reverse diffusion of solute from the draw solution is inescapable in the current stage of FO technology, and attempts have been made to understand this mechanism and to quantify the amount of reverse diffusion of draw solute (Phillip et al., 2010).Since the reverse flow of draw solute is a mechanism unique to FO with respect to conventional pressure-driven membrane processes, many variables are induced and needed to be investigated. For example, the reverse solute diffusion may affect the fouling and rejection rate of FO process, and therefore have significant effects in the quality as well as quantity of product water. To date, however, very few studies on the effect of reverse solute diffusion have been reported in the literatures (Hancock et al., 2009). As a result, many critical and fundamental questions remain be answered. In this study, the FO organic/colloidal fouling characteristics are investigated with respect to the role of salt reverse diffusion. We also examine the FO organic/colloidal fouling reversibility by employing the physical impact on the organic/colloidal fouling layer. Based on the results obtained, the important mechanisms controlling the fouling in FO are elucidated and delineated.
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TABLE OF CONTENTS
ABSTRACT
LIST OF FIGURES
CHAPTER 1
INTRODUCTION
1.1 Introduction
CHAPTER 2
LITERATURE SURVEY
2.1 The source of driving force in FO process
2.1.1 Draw solution
2.1.2 Draw solution recovery methods
2.2 Flux in FO process
2.2.1 ICP (Internal Concentration Polarization
2.2.2 Membrane
2.3 Fouling in FO process
2.3.1 Mechanism
2.3.2 Reversibility
CHAPTER 3
MATERIALS AND METHODS
3.1 Organic foulants
3.2 Colloidal particle foulants
3.3 Evaluation of colloidal stability of silica particles
3.4 Measuring the resistance of membrane and colloidal fouling layer
3.4.1 Membrane resistance
3.4.2 Colloidal fouling layer resistance
3.5 FO Membrane
3.6 FO and RO systems
3.7 Fouling tests
CHAPTER 4
RESULTS AND DISCUSSION
4.1 Organic fouling in forward osmosis
4.1.1 Organic fouling in FO and RO
4.1.2 Cake-enhanced osmotic pressure is an important fouling mechanism in FO
4.1.3 Fouling in FO is reversible
4.1.4 Fouling in FO is mitigated at higher cross-flow velocities
4.2 Colloidal fouling in forward osmosis
4.2.1 Characteristics of membrane and colloidal particles
4.2.2 Flux decline is governed by cake-enhanced osmotic pressure
4.2.3 Effect of solution pH on colloidal fouling
4.2.3.1 Fouling with a monodispersecolloidal suspension
4.2.3.2 Fouling with a polydispersecolloidal suspension
4.2.4 Effect of draw solution reverse diffusion on fouling with polydisperse colloidal suspension
4.2.5 Impact of reverse diffusion of draw solution on reversibility of colloidal fouling
CHAPTER 5
CONCLUSIOS
REFERENCES
