Browsing by Author "Yang, Hui Ling"

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Characteristics of RO foulants in a brackish water desalination plant
(2008-03-01)
Yang, Hui Ling
;
Huang, Chihpin
;
Pan, Jill R.
;
環境工程研究所
;
Institute of Environmental Engineering
This study identified the membrane fouling of a two-stage RO process of the Bai-sha brackish water desalination plant facing serious fouling problems. Two membrane modules, one from each stage, were autopsied and diagnosed for the cause for the failure of the RO system. Different morphologies were exhibited on the fouled membrane. Results suggested that the fouling on the first-stage membrane tended to be organic and biological, while that on the second-stage membrane appeared to be scaling. Higher than 85% of the foulants on the first stage membrane were organic substances in opposed to the 5 to 8% of those on the second stage membrane. However, the total organic matter on the second stage membrane was more than that on the first stage one. The thick layer of sealants on the surface of the second-stage membrane was identified to be calcium carbonate of which the crystal was clearly seen in the SEM images. The scaling was thickest at the outlet of the membrane. Huge amount of microbes were found on both membranes. The FTIR results also suggested the existence of extracellular polymeric substance (EPS) on the first stage membrane. This study recommended that the recovery rate, pH and the potential for bio-fouling should be defined at the real operation.
Seasonal fouling on seawater desalination RO membrane
(2010-01-15)
Yang, Hui Ling
;
Huang, Chihpin
;
Lin, Justin Chun-Te
;
環境工程研究所
;
Institute of Environmental Engineering
A pilot study has been performed to investigate the seasonal characteristic of seawater reverse osmosis (RO) membrane fouling. Two batches of experiment during summer and winter were both performed 18 days to provide a clear picture on microbial population variability. The feed water of the pilot from seawater desalination plant has significant difference in temperature and silica content between the two seasons. In our experiments, scaling and biofouling are more serious in summer. And the permeate flux decline is closely related to the rise in microbial population, and it was dominated by cell multiplication rather than adhesion. In addition, the summer cell multiplication is much more abundant. Moreover, the extracellular polymeric substance (EPS) feature intensity detected by Fourier-transform infrared spectroscopy was also stronger in summer. The abundant EPS was one of the major reasons to cause the inorganic matter adsorption. Si, Al, Fe, Ca and Mg were found as the major inorganic foulants deposited on the Ro membranes. Silica and calcium in summer appeared obvious higher amounts than that in winter, which indicated that they should be affected by microbial action directly or indirectly more than other elements. In summary, there exists a seasonal effect on membrane scaling and fouling, and scaling is associated with biofouling in some degree. Further researches could be focus on actual association between microbial action and inorganic fouling. (C) 2009 Elsevier B.V. All rights reserved.