Browsing by Author "Su, Yu-Chun"

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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.
Effect of sludge characteristics on membrane fouling in membrane bioreactors
(2010-03-01)
Pan, Jill Ruhsing
;
Su, Yu-Chun
;
Huang, Chihpin
;
Lee, Hsin-Chieh
;
環境工程研究所
In this study, the impact of sludge characteristics on membrane fouling in a submerged membrane bioreactor (MBR) was investigated. Bulking sludge due to excess growth of filamentous bacteria was changed to normal sludge by use of an aerobic selector. Excellent effluent quality was achieved in the MBR regardless of the quality of the sludge of the bioreactor. The removal rates of total organic carbon (TOC) and ammonia nitrogen were maintained at around 98 and 99%, respectively, during the entire experiment. However, serious fouling was observed during the occurrence of the bulking sludge despite having larger particle size distribution. Capillary suction time (CST) was found highly related to the amount of soluble microbial products (SMP) and membrane fouling. Therefore, it could be used as a simple indicator for SMP and fouling potential. Filamentous bacteria were found to produce more SMP including soluble polysaccharides and soluble proteins in the mixed liquor, which resulted in severe fouling. In particular, the release of high concentration of soluble polysaccharides resulted in serious fouling in bulking sludge. Bound EPS which was found similar in the normal sludge and bulking sludge was not the main cause for membrane fouling. In conclusion, solutes in mixed liquor such as SMP are responsible for membrane fouling, which cannot be prevented by increasing shear stress. (C) 2009 Elsevier B.V. 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
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Huang, Chihpin
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Su, Yu-Chun
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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.
Enhance the photocatalytic activity for the degradation of organic contaminants in water by incorporating TiO(2) with zero-valent iron
(2010-01-01)
Hsieh, Wen-Pin
;
Pan, Jill Ruhsing
;
Huang, Chihping
;
Su, Yu-Chun
;
Juang, Ya-Ju
Titanium dioxide (TiO(2)) has become the most popular photocatalyst in treating persistent organic pollutants. The main disadvantage of TiO(2) is the diminishing photocatalytic activity over time due to the electron-hole pair recombination. Many studies have aimed to prolong the photocatalytic life of TiO(2). Among them, incorporation of zero-valent iron (ZVI) is one of the approaches. In this study, a novel nano TiO(2)/Fe(0) composite (NTFC) was synthesized from a nano neutral TiO(2) sol and a nano zero-valent iron (nZVI), both prepared in our laboratory. The structure, composition and physical property of the NTFC are characterized. The photocatalytic activity of the NTFC was evaluated by the reductive decolourization of an azo dye, Acid Black-24 (AB-24), and was found superior to those of nZVI and nano neutral TiO(2) sol. Evidence suggests that the enhanced activity of NTFC is highly correlated to the ratio of ferrous to ferric ion in the system. The quantities of ferrous and ferric ions in the nZVI and NTFC systems were monitored separately. In the nZVI system, the concentration of ferric ions decreased significantly with time while a high level of ferrous ions was maintained in the NTFC suspension. The ferrous/ferric ratio of the NTFC suspension was substantially increased after irradiation by UV. Evidence from EPR analysis suggests that the excited electrons in the conduction band of the TiO(2) can be trapped by the half reaction of Fe(3+)/Fe(2+). reducing the probability of electron-electron hole pair recombination and sustaining the catalytic life of TiO(2). Corrosion tests further proved that by incorporating TiO(2) with zero-valent iron the surface oxidation of nZVI can be effectively prevented. (C) 2009 Elsevier B.V. All rights reserved.
Enhance the photocatalytic activity for the degradation of organic contaminants in water by incorporating TiO2 with zero-valent iron
(2010-01-01)
Hsieh, Wen-Pin
;
Pan, Jill Ruhsing
;
Huang, Chihping
;
Su, Yu-Chun
;
Juang, Ya-Ju
Titanium dioxide (TiO2) has become the most popular photocatalyst in treating persistent organic pollutants. The main disadvantage of TiO2 is the diminishing photocatalytic activity over time due to the electron-hole pair recombination. Many studies have aimed to prolong the photocatalytic life of TiO2. Among them, incorporation of zero-valent iron (ZVI) is one of the approaches. In this study, a novel nano TiO2/Fe-0 composite (NTFC) was synthesized from a nano neutral TiO2 sol and a nano zero-valent iron (nZVI), both prepared in our laboratory. The structure, composition and physical property of the NTFC are characterized. The photocatalytic activity of the NTFC was evaluated by the reductive decolourization of an azo dye, Acid Black-24 (AB-24), and was found superior to those of nZVI and nano neutral TiO2 sol. Evidence suggests that the enhanced activity of NTFC is highly correlated to the ratio of ferrous to ferric ion in the system. The quantities of ferrous and ferric ions in the nZVI and NTFC systems were monitored separately. In the nZVI system, the concentration of ferric ions decreased significantly with time while a high level of ferrous ions was maintained in the NTFC suspension. The ferrous/ferric ratio of the NTFC suspension was substantially increased after irradiation by UV. Evidence from EPR analysis suggests that the excited electrons in the conduction band of the TiO2 can be trapped by the half reaction of Fe3+/Fe2+. reducing the probability of electron-electron hole pair recombination and sustaining the catalytic life of TiO2. Corrosion tests further proved that by incorporating TiO2 with zero-valent iron the surface oxidation of nZVI can be effectively prevented. (C) 2009 Elsevier B.V. All rights reserved.
Fouling Mitigation by TiO2 Composite Membrane in Membrane Bioreactors
(2012-03-01)
Su, Yu-Chun
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Huang, Chihpin
;
Pan, Jill Ruhsing
;
Hsieh, Wen-Pin
;
Chu, Min-Chia
Membrane bioreactors (MBRs) have attracted widespread attention in advanced water treatment because of their production of consistent and high-quality effluent. However, membrane fouling during operation has greatly hindered their application. Studies have suggested that a coating of TiO2 nanoparticles on membranes may reduce membrane fouling by enhancing the hydrophilicity of the membrane. In this study, two membranes were coated with TiO2 nanoparticles for membrane fouling mitigation. To evaluate the filtration performance of the TiO2 composite membranes, a synthetic wastewater was prepared to model the municipal wastewater for the MBR operation. The mixed liquor from the MBR was used in the filtration test to evaluate the performance of the TiO2 composite membrane. Filtration tests showed that membrane fouling was reduced substantially, which was attributable to the increased hydrophilicity of the membrane. Results also shows that optimal amount of coating is important in fouling mitigation. An ultrasonic washing test suggests that most of the TiO2 particles were firmly coated on the surface of the composite membrane. DOI: 10.1061/(ASCE)EE.1943-7870.0000419. (C) 2012 American Society of Civil Engineers.
Transient Performance of MBR with Flux Enhancing Polymer Addition
(2010)
Zhang, Jin Song
;
Zhou, Ji Ti
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Su, Yu-Chun
;
Fane, Anthony G.
;
環境工程研究所
The polymeric membrane performance enhancer (MPE50) was applied in two parallel submerged membrane bioreactors to test its effect on membrane fouling. Although the flux enhancer showed significant benefit, the effect of dosage termination caused a dramatic drop in performance relative to the control. The MBRs were compared in three carefully controlled runs performed over 155 days. The total organic carbon (TOC), EPS, and particle size data were collected at regular intervals during the entire operation. In run 1, after a start-up period of 62 days, a stable state was achieved in both MBRs. In run 2, a one-off 400mg/L MPE and 15mg/L MPE daily maintenance dosage were applied in one reactor for 60 days. The ocritical fluxo determined by the flux stepping test was increased by 50% from 20 LMH to 30 LMH after the addition of MPE. Long-term experiments were implemented at three separate levels of constant flux, namely 20, 30, and 40 LMH. At the flux of 20 LMH (below the ocritical fluxo of both reactors with and without MPE), the performance in both reactors was similar. At the flux of 30 LMH (above the ocritical fluxo of the MBR without MPE but below the ocritical fluxo of the MBR with MPE), the addition of MPE was found to mitigate membrane fouling. At a flux of 40 LMH (above the critical flux for both reactors), the TMP rise in the MBR with MPE was slower than the MBR without MPE, although the performance of both MBRs was poor. The performance differences correlated with the increase in the particle size distribution of the activated sludge as well as the low level of SMP and EPS (mainly polysaccharides) concentrations in the supernatant during steady state. In run 3, after terminating the MPE addition, the membrane performance was found to be significantly worse than the MBR without MPE, which suggests that the continuous maintenance dose of MPE is essential upon MPE application to the MBR.
Treatment of Reactive Black 5 by combined electrocoagulation-granular activated carbon adsorption-microwave regeneration process
(2010-03-15)
Chang, Shih-Hsien
;
Wang, Kai-Sung
;
Liang, Hsiu-Hao
;
Chen, Hsueh-Yu
;
Li, Heng-Ching
Treatment of an azo dye, Reactive Black 5 (RB5) by combined electrocoagulation-activated carbon adsorption-microwave regeneration process was evaluated. The toxicity was also monitored by the Vibrio fischeri light inhibition test. GAC of 100 g L(-1) sorbed 82% of RB5 (100 mg L(-1)) within 4h. RB5-loaded GAC was not effectively regenerated by microwave irradiation (800W, 30s). Electrocoagulation showed high decolorization of RB5 within 8 min at pH(0) of 7, current density of 277 A m(-2), and NaCl of 1 g L(-1). However, 61% COD residue remained after treatment and toxicity was high (100% light inhibition). GAC of 20g L(-1) effectively removed COD and toxicity of electrocoagulation-treated solution within 4h. Microwave irradiation effectively regenerated intermediate-loaded GAC within 30s at power of 800 W, GAC/water ratio of 20 g L(-1), and pH of 7.8. The adsorption capacity of GAC for COD removal from the electrocoagulation-treated solution did not significantly decrease at the first 7 cycles of adsorption/regeneration. The adsorption capacity of GAC for removal of both A(265) (benzene-related groups) and toxicity slightly decreased after the 6th cycle. (C) 2009 Elsevier B.V. All rights reserved.