Browsing by Author "Tran-Ngoc-Phu Nguyen"

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Comparison of membrane foulants occurred under different sub-critical flux conditions in a membrane bioreactor (MBR)
(2014-08-01)
Tran-Ngoc-Phu Nguyen
;
Su, Yu-Chun
;
Pan, Jill Ruhsing
;
Huang, Chihpin
;
環境工程研究所
Membrane fouling precludes the widespread application of membrane filtration system from treating wastewater and drinking water, and occurs even under sub-critical flux operations. Hence the characteristics and behavior of membrane foulants should be thoroughly investigated, so as to find ways to reduce membrane fouling in membrane bioreactors. The purpose of this study is to compare the membrane fouling potential at different sub-critical flux operations and for different hydrophobic/hydrophilic membranes, and to investigate the vertical distribution of membrane foulants in a cake layer. Results showed that higher fouling propensity which occurred under 80% of critical flux of hydrophilic membrane was associated with the soluble fraction of proteins and polysaccharides, compared with 60% of critical flux. The cell-bound components were dominant under hydrophobic membrane operation. The highest concentration of proteins and polysaccharides was found between 40% and 80% of the depth of the cake layer. (C) 2014 Elsevier Ltd. All rights reserved.
Effects of electro-coagulation on fouling mitigation and sludge characteristics in a coagulation-assisted membrane bioreactor
(2015-12-01)
Hua, Lap-Cuong
;
Huang, Chihpin
;
Su, Yu-Chun
;
Tran-Ngoc-Phu Nguyen
;
Chen, Pei-Chung
Although much research effort has focused on methods to mitigate fouling of membrane bioreactors (MBRs), fouling is still inevitable. This paper aims to corroborate the roles of electro-coagulation approach within a coagulation-assisted MBR, termed electro-MBR. The effects of electro-coagulation on sludge characteristics and fouling behavior were investigated. A batch-scale experiment was carried out to identify an optimum electric current condition for electro-MBR study, in which the electro-MBR and a traditional MBR were identically set for numerous comparisons. The average fouling rate was substantially reduced 7.8 fold resulting in no chemical cleaning requirements during the entire operation of the electro-MBR. Enhanced sludge compressibility and controlled growth of filamentous bacteria positively affected by electro-coagulation were also obtained in the electro-MBR. This paper suggests that fouling mitigation in electro-MBR can be attributed to two mechanisms; (i) charge neutralization and adsorption for soluble foulants; (ii) electro-chemical oxidation for bound foulants. Furthermore, we conclude that electro-coagulation can simultaneously alter morphology and microbial structure of sludge flocs to become more compressible with lower fouling tendency, which would be beneficial for the mitigation of membrane fouling in electro-MBR. (C) 2015 Elsevier B.V. All rights reserved.
Nitrate removal and extracellular polymeric substances of autohydrogenotrophic bacteria under various pH and hydrogen flow rates
(2018-01-01)
Tran-Ngoc-Phu Nguyen
;
Chen, Pei-Chung
;
Huang, Chihpin
;
環境工程研究所
;
Institute of Environmental Engineering
In recent years there has been an increasing interest in the use of autohydrogenotrophic bacteria to treat nitrate from wastewater. However, our knowledge about the characteristics of extracellular polymeric substances (EPS) releasing by these activities is not yet very advanced. This study aimed to investigate the change in EPS compositions under various pH values and hydrogen flow rates, taking into consideration nitrogen removal. Results showed that pH 7.5 and a hydrogen flow rate of 90 mL/min were the optimal operating conditions, resulting in 100% nitrogen removal after 6 hr of operation. Soluble and bound polysaccharides decreased, while bound proteins increased with increasing pH. Polysaccharides increased with increasing hydrogen flow rate. No significant change of bound proteins was observed at various hydrogen flow rates. (C) 2017 The Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences. Published by Elsevier B.V.