Browsing by Author "Pan, Jill R."

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A hybrid electrochemical advanced oxidation/microfiltration system using BDD/Ti anode for acid yellow 36 dye wastewater treatment
(2013-12-13)
Juang, Yaju
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Nurhayati, Ervin
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Huang, Chihpin
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Pan, Jill R.
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Huang, Shihming
Conductive diamond is an excellent electrode material due to its resistance to corrosion, wide potential window, and mechanical stability. Diamond doped with boron (BDD) as the anode in electrooxidation (EO) reactor to degrade trace but refractory pollutants from wastewater has received enormous attention recently. In this study, an innovative BDD/Ti electrooxidation-microfiltration (EO/MF) hybrid system was designed and tested for simultaneous removal of refractory organics and particles in dye wastewater. The system was fabricated in a tubular fashion with BDD/Ti as the anode, stainless steel (SS) as the cathode, and a ceramic membrane in between for filtration practice. The synthetic dye wastewater contained acid yellow 36 (AY-36) as the model organic pollutant while kaolin was added to make up the particles in the suspension. The experiments were operated in a continuous up-flow mode at pH 3 with a current density of 30 mA/cm(2). A complete COD removal and more than 90% removals of color and turbidity from the dye wastewater were achieved, suggesting that particles can be removed via MF would not hinder the performance of EO. In conclusion, the single stage hybrid system of BDD/Ti-EO/MF can be a potent treatment process for dye wastewater. (C) 2013 Elsevier B.V. All rights reserved.
Characteristics of membrane fouling in submerged membrane bioreactor under sub-critical flux operation
(2008)
Su, Y. C.
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Huang, C. P.
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Pan, Jill R.
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Lee, H. C.
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環境工程研究所
Recently, the membrane bioreactor ( MBR) process has become one of the novel technologies to enhance the performance of biological treatment of wastewater. Membrane bioreactor process uses the membrane unit to replace a sediment tank, and this can greatly enhance treatment performance. However, membrane fouling in MBR restricts its widespread application because it leads to permeate flux decline, making more frequent membrane cleaning and replacement necessary, which then increases operating and maintenance costs. This study investigated the sludge characteristics in membrane fouling under sub- critical flux operation and also assessed the effect of shear stress on membrane fouling. Membrane fouling was slow under sub- critical flux operation. However, as filamentous microbes became dominant in the reactor, membrane fouling increased dramatically due to the increased viscosity and polysaccharides. A close link was found between membrane fouling and the amount of polysaccharides in soluble EPS. The predominant resistance was the cake resistance which could be minimized by increasing the shear stress. However, the resistance of colloids and solutes was not apparently reduced by increasing shear stress. Therefore, smaller particles such as macromolecules ( e. g. polysaccharides) may play an important role in membrane fouling under sub- critical flux operation.
Characteristics of RO foulants in a brackish water desalination plant
(2008-03-01)
Yang, Hui Ling
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Huang, Chihpin
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Pan, Jill R.
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環境工程研究所
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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.
Coagulation behavior of Al-13 aggregates
(2008-10-01)
Lin, Jr-Lin
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Chin, Ching-Ju M.
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Huang, Chihpin
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Pan, Jill R.
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Wang, Dongsheng
The coagulation behavior of Al-13 aggregates formed in coagulation of kaolin was investigated by small angle static light scattering (SASLS), solid-state Al-27 NMR and tapping mode atomic force microscope (TM-AFM). A kaolin suspension was coagulated by PACl containing high content of Al-13 polycation (PACl-Al-13). The results indicated that Al-13 was predominant in destabilizing kaolin particles for PACl-Al-13 coagulation even though at alkaline pH (pH 10). At such high pH, Al-13 aggregates were observed when the dosage of PACl-Al-13 was increased. In addition, the mechanism of coagulation by PACl-Al-13 at alkaline pH was affected by dosage. When the dosage was insufficient, coagulation was caused by electrostatic patch, which led to compact flocs with high fractal dimension (D-f) Interparticle bridging dominated the coagulation when the coagulant dosage approached the plateau of adsorption, which caused the looser flocs with low Df. The in-situ AFM scanning in liquid system proved that the existence of linear A113 aggregates composed of a chain of coiled Al-13 in coagulation by PACl-Al-13 at a high dosage and alkaline pH. Meanwhile, several coiled Al-13 aggregates with various dimensions were observed at such condition. Crown Copyright (C) 2008 Published by Elsevier Ltd. All rights reserved.
Coagulation dynamics of fractal flocs induced by enmeshment and electrostatic patch mechanisms
(2008-11-01)
Lin, Jr-Lin
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Huang, Chihpin
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Chin, Ching-Ju M.
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Pan, Jill R.
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環境工程研究所
The size and structure of flocs during floc formation were monitored for various coagulation mechanisms. Two distinctive mechanisms, namely, enmeshment and electrostatic patch, govern the dynamics of kaolin particles coagulation by polyaluminurn. chloride (PACl). They were investigated by small angle static light scattering (SASLS) and solid-state Al-27 NMR. In addition, a novel wet SEM (WSEM) was used in-situ to image the morphology of the aggregate in aqueous solution. Synthetic suspended particles were coagulated by two PACl products, a commercial product (PACl) and one laboratory product (PACl-E). The PACl-E contained more than 60% Al-13 while the PACI contained only 7% Al-13, with large percentage of colloidal Al. For coagulation by PACI at neutral pH and high dosage where the strong repulsion between particles occurs, the enmeshment ruled by reaction-limited aggregation (RLA) results in larger sweep flocs as well as higher fractal dimensional structure. For coagulation by PACl-E at alkaline pH and low dosage, the flocs were coagulated predominately by electrostatic patch with Al-13 aggregates. At such condition, it is likely that diffusion-limited aggregation (DLA) predominately rule PACl-E coagulation. The fractal dimension (D-s) values of PACl and PACl-E flocs formed at enmeshment and electrostatic patch increased with dosage, respectively. When breakage of flocs occurs, the breakage rate of PACI-E flocs is slower than that of sweep flocs. By WSEM imaging, the adsorption of spherical Al precipitates onto the particles was observed to form sweep flocs with a rough and ragged contour, while the PACI-E flocs were formed with a smooth and glossy structure. (C) 2008 Elsevier Ltd. All rights reserved.
Effect of coagulation mechanism on membrane permeability in coagulation-assisted microfiltration for spent filter backwash water recycling
(2011-03-20)
Huang, Chihpin
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Lin, Jr-Lin
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Lee, Wen-Shan
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Pan, Jill R.
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Zhao, Bingqing
Coagulation is an effective pre-treatment process in membrane filtration for recycling spent filter backwash water (SFBW). To optimize the operation of the coagulation/filtration process for SFBW recycling, it is important to understand the critical role of coagulation mechanism on membrane filtration. In this study, SFBW samples were coagulated with polyaluminum chloride (PACI), followed by a dead-end micro-filtration (MF), and the mean permeate flux and permeate quality were determined. The results showed that pre-coagulation improved the flux decline and the degree of the improvement was closely related to coagulation mechanisms. The permeate flux was enhanced most effectively by precipitation charge neutralization (PCN) coagulation, followed by charge neutralization and then sweep flocculation. Close examination of cake properties indicated that the reduced cake resistance (R(c)) was subjected to the coagulated SFBW flocs in response to different coagulation mechanism. Smaller flocs, induced by PCN, were more compact and stronger, forming less compressible cake, which facilitated membrane filtration, while slower membrane filtration was observed when more compressible cake formed from larger flocs of looser and weaker structure. Coagulation mechanism also governed the size distribution of SFBW floc, which is strongly related to the subsequent cake compressibility as well as membrane permeability in membrane filtration. (C) 2011 Elsevier B.V. All rights reserved.
Enhanced particle destabilization and aggregation by flash-mixing coagulation for drinking water treatment
(2013-08-30)
Lin, Jr-Lin
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Pan, Jill R.
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Huang, Chihpin
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環境工程研究所
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生物科技學系
In water treatment plants (WTPs), the operation of rapid mixing in coagulation units dominates particle destabilization and the formation of flocs. The goal of this study was to investigate the effect of enhanced rapid-mixing intensity (velocity gradient [G]) on the performance of coagulation for natural turbid water treatment. Two surface-water samples of low and high turbidity were coagulated by using polyaluminum chloride (PACl), with G values ranging from 200 to 800 s(-1),and the destabilization of particles and dissolved organic matter (DOM) was determined, followed by measurement of filterability of the supernatant. Furthermore, the effect of high rapid mixing on the coagulation efficiency was studied by using a pilot-scale, in-line instantaneous flash mixer (IFM) which could generate much higher G than a conventional mechanical mixing of WTP. The results of Jar test showed that the enhanced reduction in turbidity was accompanied by the improved filterability of the supernatant, which was due to the formation of larger flocs with strong structure in response to higher rapid-mixing intensity, especially for low-turbidity water. It was found that the fractal dimension (D-f) of coagulated flocs is inversely proportional to the recovery factor of broken flocs. The in-line IFM with intensive mixing (G > 5000 s(-1)) substantially improved the removal of particles and DOM, as a result of the formation of large flocs. Crown Copyright (C) 2013 Published by Elsevier B.V. All rights reserved.
Factors affecting phenol transfer through polydimethylsiloxane composite membrane
(2008-12-31)
Lee, Mao-Sung
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Huang, Chihpin
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Lee, Kueir-Rarn
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Pan, Jill R.
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Chang, Wang-Kuan
Polydimethylsiloxane composite membrane was employed for the separation of phenol and sodium chloride in synthetic wastewater. The major operational parameters affecting phenol transfer through this composite membrane were screened by the orthogonal array and range analysis. The results showed that the significance of parameters on the permeate flux followed the order of phenol concentration, membrane skin layer thickness, recirculation rate, and sodium chloride concentration after 6 and 48 h operations. Optimal operation range was determined by the response surface methodology coupled with central composite design. The higher was the phenol concentration in the influent or the thicker was the membrane skin layer thickness, the higher was the permeate flux through membrane. Also, the higher was the recirculation rate, the higher was the permeate flux through membrane.
Operation of fixed-bed bioreactor for polluted surface water treatment
(2007)
Lee, Tinlai
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Huang, Chihpin
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You, Hueysong
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Pan, Jill R.
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環境工程研究所
Dissolved organic matters and ammonia nitrogen are serious contaminants of surface water in Taiwan. These contaminants can interfere with the water treatment process and cause biological instability in the finished water. One solution is to employ a biological treatment stage prior to the conventional water treatment process. A continuous flow biological filter packed with reticulated PU foam was used to remove ammonia nitrogen and organic materials before the conventional water treatment practice. The effect of its operation mode, namely, empty bed contact time (EBCT) and backwash, on the removal efficiencies of ammonia and organic matter was examined. The results suggested that ammonia nitrogen and organic nitrogen can be effectively removed by controlling the operation mode of the biological fixed bed. Efficient ammonia nitrogen removal was achieved upon the combination of the backwash mode with short EBCT or extended EBCT without the backwash. Efficient organic nitrogen and DOC removals were observed at short EBCT without the backwash. This study provides insights into the function of biofiltration, which benefits the design of a fixed-bed bioreactor for the treatment of polluted surface water.
Operational performance of sludge blanket in clarification: effect of organic matter
(2007-05-01)
Huang, Chihpin
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Lee, Tinlai
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Pan, Jill R.
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Hon, Jaiwai
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環境工程研究所
Sludge blanket clarifiers (SBC) are presently an important unit of the water treatment process in Taiwan. Most studies concerning SBC have revolved around the treatment efficiency on turbidities. In Taiwan most of the raw water sources for water treatment plants are contaminated with organic substances, which often interfere with the operation Of SBC. in this study, the effects of organic materials on the formation of the sludge blanket and its were examined. Humic acid and salicylic acid were added in water to simulate natural waters polluted with organic materials of high and low molecular weights. The addition of humic acid accelerated the formation of a stable sludge blanket, however, the sludge blanket so formed contained less solid. Opposite effects were discovered with salicylic acid. Nevertheless, both organics enhanced the efficiency of turbidity removal by SBC. Large organic molecules were easily removed by SBC. Coagulant addition had no significant effect on turbidity removal although the formation time for a sludge blanket was shortened. To successfully operate SBC, the occurrence and types of organic materials must be monitored.
Recycling MSWI bottom and fly ash as raw materials for Portland cement
(2008)
Pan, Jill R.
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Huang, Chihpin
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Kuo, Jung-Jen
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Lin, Sheng-Huan
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環境工程研究所
Municipal solid waste incineration (MSWI) ash is rich in heavy metals and salts. The disposal of MSWI ash without proper treatment may cause serious environmental problems. Recently, the local cement industry in Taiwan has played an important role in the management of solid wastes because it can utilize various kinds of wastes as either fuels or raw materials. The objective of this study is to assess the possibility of MSWI ash reuse as a raw material for cement production. The ash was first washed with water and acid to remove the chlorides, which could cause serious corrosion in the cement kiln. Various amounts of pre-washed ash were added to replace the clay component of the raw materials for cement production. The allowable limits of chloride in the fly ash and bottom ash were found to be 11.75% and 3.50% respectively. The results indicate that cement production can be a feasible alternative for MSWI ash management. It is also evident that the addition of either fly ash or bottom ash did not have any effect on the compressive strength of the clinker. Cement products conformed to the Chinese National Standard (CNS) of Type II Portland cement with one exception, the setting time of the clinker was much longer. (c) 2007 Elsevier Ltd. All rights reserved.
The origin of Al(OH)(3)-rich and Al(13)-aggregate flocs composition in PACl coagulation
(2009-09-01)
Lin, Jr-Lin
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Huang, Chihpin
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Chin, Ching-Ju M.
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Pan, Jill R.
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環境工程研究所
The composition of hydrolyzed Al species is essential for the understanding of coagulation with Al-based coagulants. Surface characteristics of flocs formed by coagulation with two distinct polyaluminum chloride (PACl) coagulants were identified. One commercial coagulant (PACl-C) with voluminous monomeric Al and colloidal Al(OH)(3) and a custom-made PACl (PACl-Al(13)) containing high Al(13) content were applied to destabilize kaolin particles. The flocs formed by PACl-C and PACl-Al(13) at neutral and alkaline pH ranges, respectively, were observed by FE-SEM and HR-TEM. In addition, the Al composition of these flocs was characterized by XPS and HR-XRD, and the imaging of Al(OH)(3) precipitates and Al(13) aggregates were conducted by SEM as well as tapping mode AFM in liquid system. The observations of flocs indicate that the morphology of Al(OH)(3)-rich flocs are fluffy and porous around the edge of flocs, while the Al(13)-aggregate flocs have a glossy contour and irregular structure. Both Al(OH)(3)-rich and Al(13)-aggregate flocs do not possess well-formed crystalline structure except for the Al(13)-like crystal exists in the Al(13)-aggregate flocs. Among Al(OH)(3) precipitates, colloidal Al(OH)(3) is micro-scale in size, while amorphous Al(OH)(3) is nano-scale. During the formation of Al(13) aggregates, some coiled and clustered Al(13) aggregates with smoother surface were observed. The XPS study on floc surface showed that tetrahedral (Al(IV))/octahedral (Al(VI)) Al ratio on the surfaces of PACl-C and PACl-Al(13) flocs is 1:1.6 and 1:9.9, respectively. Of the in situ formed Al(13), almost half of Al-hydroxide precipitates on the surface of Al(OH)(3)-rich flocs possess the Al(IV) center. It also found that the irregularly aggregated Al(13) with a similar Al(13) Crystalline structure subsists on the surface of Al(13)-aggregate flocs. (C) 2009 Elsevier Ltd. All rights reserved.
The origin of Al(OH)(3)-rich and Al-13-aggregate flocs composition in PACl coagulation
(2009-09-01)
Lin, Jr-Lin
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Huang, Chihpin
;
Chin, Ching-Ju M.
;
Pan, Jill R.
;
環境工程研究所
The composition of hydrolyzed Al species is essential for the understanding of coagulation with Al-based coagulants. Surface characteristics of flocs formed by coagulation with two distinct polyaluminum chloride (PACl) coagulants were identified. One commercial coagulant (PACl-C) with voluminous monomeric Al and colloidal Al(OH)(3) and a custom-made PACl (PACl-Al-13) containing high Al-13 content were applied to destabilize kaolin particles. The flocs formed by PACl-C and PACl-Al-13 at neutral and alkaline pH ranges, respectively, were observed by FE-SEM and HR-TEM. In addition, the Al composition of these flocs was characterized by XPS and HR-XRD, and the imaging of Al(OH)(3) precipitates and Al-13 aggregates were conducted by SEM as well as tapping mode AFM in liquid system. The observations of flocs indicate that the morphology of Al(OH)(3)-rich flocs are fluffy and porous around the edge of flocs, while the Al-13-aggregate flocs have a glossy contour and irregular structure. Both Al(OH)(3)-rich and Al-13-aggregate flocs do not possess well-formed crystalline structure except for the Al-13-like crystal exists in the Al-13-aggregate flocs. Among Al(OH)(3) precipitates, colloidal Al(OH)(3) is micro-scale in size, while amorphous Al(OH)(3) is nano-scale. During the formation of Al-13 aggregates, some coiled and clustered Al-13 aggregates with smoother surface were observed. The XPS study on floc surface showed that tetrahedral (Al-IV)/octahedral (Al-VI) Al ratio on the surfaces of PACl-C and PACl-Al-13 flocs is 1:1.6 and 1:9.9, respectively. Of the in situ formed Al-13, almost half of Al-hydroxide precipitates on the surface of Al(OH)(3)-rich flocs possess the Al-IV center. It also found that the irregularly aggregated Al-13 with a similar Al-13 Crystalline structure subsists on the surface of Al-13-aggregate flocs. (C) 2009 Elsevier Ltd. All rights reserved.
Treatment of high-level arsenic-containing wastewater by fluidized bed crystallization process
(2007-03-01)
Huang, Chihpin
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Pan, Jill R.
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Lee, Maosung
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Yen, Shihming
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環境工程研究所
Gallium arsenide technology has been widely applied in the communication and optical electronics industries. The process of chip manufacturing produces a stream of wastewater unique in its low flow rate and high arsenic concentration. Fluidized bed crystallization (FBC) technology combines the advantages of a fluidized bed reactor and crystallization. It is highly efficient with low capital and operational costs, while producing no sludge. The waste from the FBC is small in volume, high in crystal purity and recyclable. Jar tests were first performed to evaluate the precipitation of arsenic sulfide. Then a lab-scale fluidized bed reactor was applied to screen critical operational parameters and the process was optimized to meet the wastewater discharge standard. The results obtained in this study confirmed that the FBC process is capable of treating wastewater containing high concentrations of arsenic, reducing the concentration to mu g L-1 levels. Sulfide dosage and operating pH are the two most significant parameters determining the residual arsenic concentration of the effluent, with optimum conditions of pH = 2 and S/As = 2.2 to meet the local discharge limit. (c) 2007 Society of Chemical Industry