Performance evaluation of two-stage spiral wound forward osmosis elements at various operation conditions

2016 ◽  
Vol 57 (51) ◽  
pp. 24583-24594 ◽  
Author(s):  
Sung-Ju Im ◽  
Gyeong-Wan Go ◽  
Sang-Hak Lee ◽  
Gi-Ho Park ◽  
Am Jang
Membranes ◽  
2020 ◽  
Vol 10 (3) ◽  
pp. 53
Author(s):  
Sungyun Lee

Forward osmosis (FO) technology has increasingly attracted attention owing to its low operational energy and low fouling propensity. Despite extensive investigations on FO, very few module-scale FO studies on the operation and design of the FO process have been conducted. In this paper, a simple and practical FO process design parameter called normalized membrane area is suggested based on a performance analysis of spiral-wound FO elements. The influence of operation factors on operating pressures and water recovery was investigated using 8-inch spiral wound elements in the continuous operation mode. The membrane area was adjusted by series connection of FO elements to a maximum value of 46 m2 (three elements). The feed and draw flow rates were varied between 5 and 15 LPM under various feed (10, 20, and 30 g/L) and draw (58.4 and 233.8 g/L) concentration combinations. The analysis of flow rates (feed, draw, and permeate flow rates) indicated not only high flow channel resistance on the draw side but also high permeate flow rates can induce higher operating pressures owing to strong mutual interaction of the feed and the draw streams. Feed water recovery was focused on as a key performance index, and the experimental recovery (RExp) and theoretical maximum recovery (RTh) values were compared. The results revealed the significance of the feed flow rate and the membrane area in terms of enhancing the water recovery performance. In addition, a clear relationship was observed between the membrane area normalized by the initial feed flow rates and the water recovery ratio (RExp/RTh), even though the applied operation conditions were different. Finally, an empirical equation to estimate the required membrane area of spiral-wound FO was proposed for the FO process design. The equation can be used to predict water recovery of FO systems as well, for example, if an FO system is operated at 0.08 m2L−1h of the normalized membrane area, the system is expected to offer 78% of the RTh value.


2011 ◽  
Vol 102 (10) ◽  
pp. 5645-5652 ◽  
Author(s):  
A.O. Babatunde ◽  
Y.Q. Zhao ◽  
R.J. Doyle ◽  
S.M. Rackard ◽  
J.L.G. Kumar ◽  
...  

Author(s):  
Hoda Golshani ◽  
Mohammad Khoveyni ◽  
Hadi Bagherzadeh Valami ◽  
Robabeh Eslami

2020 ◽  
Author(s):  
Na Du ◽  
Man Yuan ◽  
Peng Wu ◽  
Zhiwu Li

Abstract Background: In the context of China’s aging population, comprehensive medical care, convenient diagnosis, comprehensive medical care and elderly care services are increasingly needed. But China's medical care and elderly care service system is still immature. This study aims to build a performance evaluation index/criteria system for the combination of medical care and elderly care services and present an empirical approach to assess them.Methods: A two-stage DEA approach is taken: 1) establish a performance evaluation index system for the combination of medical care and elderly care services, 2) adopt a two-stage DEA to evaluate the performance of 30 pension institutions in China, and 3) Determine and identify important criteria to improve the efficiency of pension institutions. Results: The results show that the two-stage DEA accounted for a relatively high affiance of medical and nursing care services, but resource allocation still needs to be further optimized. Institutions with ineffective DEA need to reduce the five factors of operations, management, fixed assets, technology and services in the input dimension. In the output dimension, the service evaluation effect and safety management effect need to be improved. The performance of combined old-age care and medical care in old-age institutions can be improved in terms of investment in fixed assets, methods of capital subsidies, supervision and management, as well as standardized operations.Conclusions: This study establish a performance evaluation index system for the combination of medical care and elderly care services and present a two-stage DEA empirical approach to evaluate the performance of 30 pension institutions in China, which provides the method supports for decision-makers and researchers in performing evaluation of pension institutions in China, outlines the suggestions in improving them.


1995 ◽  
pp. 1219-1220
Author(s):  
I. Gorostiza ◽  
M. Zallo ◽  
A. I. San Vicente ◽  
E. Quintana ◽  
I. Muguruza

Desalination ◽  
2018 ◽  
Vol 433 ◽  
pp. 120-131 ◽  
Author(s):  
Jongmin Jeon ◽  
Jaehak Jung ◽  
Sangho Lee ◽  
Joon Young Choi ◽  
Suhan Kim

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