Earticle

초록

영어

The issues of water shortage and depletion of fresh water supply due to climate change place a great demand on alternative water resources. The increased need to secure a high quality water supply from various sources has resulted in the emergence of advanced membrane technologies, especially seawater desalination by reverse osmosis (RO). Compared with typical thermal driven desalination processes like MSF and MED, RO process requires less energy consumption, for this reason, the global RO market has been increasing more than 10 % annually. Despite the major advancements in RO desalination technology, which resulted in significant reductions in cost and energy use, its efficiency and sustainable operation are hampered by membrane fouling and by the considerable energy consumption [1].A recently resurgent membrane process, forward osmosis (FO) is considered to be a potential, sustainable alternative to conventional pressure-driven membrane processes. The advantages of FO technology include; (i) it operates without hydraulic pressure, thus with lower energy consumption, (ii) it can achieve high rejection of a wide range of contaminants, and (iii) it may have lower fouling potential than pressure-driven membrane processes because of the absence of applied hydraulic pressure. This presentation will discuss the future of seawater desalination technologies which would overcome limitations of current RO-based desalting process. More specifically, the concept of FO-RO hybrid desalination process is first explored to improve the energy efficiency and to increase water recovery and productivity. Recent research topics and developments in FO technology are also presented with focusing on the opportunities and challenges. Fouling behavior in FO has been investigated systematically, and the governing mechanism inducing the decline in the productivity of FO process is delineated. In FO, salt reversely diffused from the draw to the feed side results in an accelerated cake-enhanced osmotic pressure (CEOP) and corresponding severe permeate flux decline. Colloidal fouling in FO is also enhanced by reverse salt diffusion because it creates salinity-rich environment near the membrane surface, which prompts particle destabilization and aggregation. Fouling reversibility was also examined by varying the cross-flow velocity during the FO fouling runs. The permeate flux during organic/colloidal fouling in FO recovered almost completely with increasing cross-flow velocity. Our results suggest that fouling in FO could be controlled effectively by optimizing the hydrodynamics in the feed stream without employing chemical cleaning [2]. As a new concept to improve the productivity of FO process, PA-FO (Pressure- added FO) is suggested and its mechanistic features are investigated. In PA-FO, in addition to the chemical osmotic pressure, a low mechanical pressure is applied to increase the driving force for the water separation and corresponding the permeate water flux. The experimentally measured water fluxes generated in PA-FO are consistently lower than those predicted by modeling equation calculating the water flux in PA-FO process which accounts for the effects of applied hydraulic pressure. This result can be explained by the effect of the permeate water flux on the severity of internal concentration polarization (ICP) within the membrane support layer. As the permeate water flux increases, draw solution within the membrane support layer becomes more diluted, which in turn, decreases the effective osmotic pressure gradient at the interface between the support layer and the active layer. Based on the results obtained, we propose new concept to interpret the process efficiency of PA-FO.

키워드

저자

• Seungkwan HONG [ School of Civil, Environmental & Architectural Engineering, Korea University, 1-5 Ga, Anam-Dong, Sungbuk-Gu, Seoul 136-713, Republic of Korea. ]
• Chanhee BOO [ School of Civil, Environmental & Architectural Engineering, Korea University, 1-5 Ga, Anam-Dong, Sungbuk-Gu, Seoul 136-713, Republic of Korea. ]
• DaAe KIM [ School of Civil, Environmental & Architectural Engineering, Korea University, 1-5 Ga, Anam-Dong, Sungbuk-Gu, Seoul 136-713, Republic of Korea. ]
• Yoontaek OH [ School of Civil, Environmental & Architectural Engineering, Korea University, 1-5 Ga, Anam-Dong, Sungbuk-Gu, Seoul 136-713, Republic of Korea. ]

참고문헌

발행기관

간행물

표지보기 관심저널 등록

• 간행물명

  한국생물공학회 학술대회

• 간기

  반년간

• 수록기간

  1985~2013

• 십진분류

  KDC 476 DDC 576