Browsing by Author "Huang, Chihpin"

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A dual TiO2/Ti-stainless steel anode for the degradation of orange G in a coupling photoelectrochemical and photo-electro-Fenton system
(2019-04-01)
Liu, Ching-Fang
;
Huangb, C. P.
;
Hu, Chi-Chang
;
Huang, Chihpin
;
環境工程研究所
A dual-anode consists of stainless steel and TiO2/Ti electrodes is used to study the kinetics of the degradation of hazardous chemicals exemplified by azo dye orange G (OG) using a coupling photoelectrochemical catalytic and photoelectro-Fenton (PEC/PEF) system. Concurrent generation of hydroxyl radicals on the TiO2/Ti photocatalyst and in-situ generation of Fenton reagents on the stainless steel electrode greatly enhances the performance of the PEC/PEF electrodes over that of the PEC and the PEF alone process. The efficiency of the PEC/PEF process is a function of Fe2+ and H2O2 concentration OH center dot in the solution bulk, which promotes the oxidative degradation of OG and its byproducts. The mean carbon oxidation state (COS) is estimated to reflect the degree of mineralization. Based on the pseudo first-order kinetics with respect to OH center dot, OG, Fe2+, the corresponding reaction rates is established. UV-Vis spectrometry reveals the presence of four major intermediates, which helps establish the OG degradation pathways. (c) 2018 Elsevier B.V. All rights reserved.
A hybrid electrochemical advanced oxidation/microfiltration system using BDD/Ti anode for acid yellow 36 dye wastewater treatment
(2013-12-13)
Juang, Yaju
;
Nurhayati, Ervin
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Huang, Chihpin
;
Pan, Jill R.
;
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.
Algal removal from cyanobacteria-rich waters by preoxidation-assisted coagulation-flotation: Effect of algogenic organic matter release on algal removal and trihalomethane formation
(2018-01-01)
Lin, Jr-Lin
;
Lap-Cuong Hua
;
Shih Kai Hung
;
Huang, Chihpin
;
環境工程研究所
The cyanobacteria-bloom in raw waters frequently causes an unpredictable chemical dosing of preoxidation and coagulation for an effective removal of algal cells in water treatment plants. This study investigated the effects of preoxidation with NaOCl and ClO2 on the coagulation-flotation effectiveness in the removal of two commonly blooming cyanobacteria species, Microcystis aeruginosa (MA) and Cylindrospermopsis raciborskii (CR), and their corresponding trihalomethane (THM) formation potential. The results showed that dual dosing with NaOCl plus ClO2 was more effective in enhancing the deformation of cyanobacterial cells compared to single dosing with NaOCl, especially for CR-rich water. Both preoxidation approaches for CR-rich water effectively reduced the CR cell count with less remained dissolved organic carbon (DOC), which benefited subsequent coagulationflotation. However, preoxidation led to an adverse release of algogenic organic matter (AOM) in the case of MA-rich water. The release of AOM resulted in a poor removal in MA cells and a large amount of THM formation after oxidation-assisted coagulation-flotation process. The reduction in THMformation potential of CR-richwaters is responsible for effective algae and DOC removal by alum coagulation. It is concluded that the species-specific characteristic of cyanobacteria and their AOM released during chlorination significantly influences the performance of coagulation-flotation for AOM removal and corresponding THM formation. (C) 2017 The Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences. Published by Elsevier B.V.
Algogenic organic matter derived DBPs: Precursor characterization, formation, and future perspectives - A review
(2019-10-02)
Hua, Lap-Cuong
;
Lai, Chun-Hsi
;
Wang, Gen-Shuh
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Lin, Tsair-Fuh
;
Huang, Chihpin
Algogenic organic matter (AOM) in water is a critical issue for sustainable treatment of drinking water, especially when algal eutrophication occurs because it is not amenable to removal by traditional coagulation/sedimentation/filtration processes. AOM is thus proved as a major precursor of disinfection by-products (DBPs). Its occurrence in water is undesirable and impacts the safety of drinking water. This review paper aims to broaden our current knowledge on the formation of AOM-derived DBPs and its precursor characterization. The future perspectives of research needs on AOM-DBP precursor characterization for an effective prediction are also given by this review. AOMs from various algal species have high-yielding potentials to produce both carbonaceous and nitrogenous DBPs upon chlorination, especially for the intracellular OM (IOM) from the algal cell. The practical treatment of eutrophic water with preoxidation thus should be used in caution to avoid the release of IOM from ruptured cells. Characterization of the physiochemical properties, such as basic parameters, optical properties, molecular weight distribution, and chemical functional groups, of AOM can give advantages for the better understanding of AOM-derived DBPs. Among the characterization tools, the fluorescent technique is highly recommended for the application of AOM-DBP prediction.
Anodic fabrication of advanced titania nanotubes photocatalysts for photoelectrocatalysis decolorization of Orange G dye
(2016-02-01)
Juang, Yaju
;
Liu, Yijin
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Nurhayati, Ervin
;
Nguyen Thi Thuy
;
Huang, Chihpin
Titania nanotubes (TNTs) were fabricated on Ti mesh substrates by the anodizing technique. The effects of preparation variables, such as anodizing voltage, time and calcination temperature on the textural characteristics and photocatalytic activity of TNTs were investigated. The surface morphology, crystalline phase, and chemical composition were analyzed using field emission-scanning electron microscopy and X-ray diffraction. The photo-electrochemical properties of TNTs were examined by voltammetry. The TNTs were tested as a photoanode for advanced oxidation processes, such as photocatalytic, electrocatalytic, and photoelectrocatalytic decolorization of Orange G dye. The well-arranged TNTs electrode prepared in this work showed a high photocurrent density of 101 mu A cm(-2) at an optimum length-to-diameter aspect ratio of 31.2. In dye decolorization tests, the electrochemical photocatalytic system using TNTs as the photoanode achieved total decolorization and 64% mineralization under extended reaction time. These results show that TNTs prepared by this method is greatly stable in prolonged use and suitable as a photoanode in the photocatalytic/photoelectrocatalytic treatments of dye wastewater. (C) 2015 Elsevier Ltd. All rights reserved.
Application of nanosilver surface modification to RO membrane and spacer for mitigating biofouling in seawater desalination
(2009-08-01)
Yang, Hui-Ling
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Lin, Justin Chun-Te
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Huang, Chihpin
;
環境工程研究所
;
Institute of Environmental Engineering
Biofouling is one the most critical problems in seawater desalination plants and science has not yet found effective ways to control it. Silver compounds and ions are historically recognized for their effective antimicrobial activity. Nanosilver particles have been applied as a biocide in many aspects of disinfection, including healthcare products and water treatment. This study proposes an innovative biofouling control approach by surface modification of the RO membrane and spacer with nanosilver coating. A chemical reduction method was used for directly coating nanosilver particles on the membrane sheet and spacer. The surface-modified membrane and spacer were tested for their antifouling performance in a cross-flow flat-sheet membrane cell, which is a part of a pilot plant in Wukan desalination plant. The silver-coating membranes and spacers, along with an unmodified membrane sheet, were tested in the membrane cell and compared on the basis of their antifouling performance. Permeate flux decline and salt rejection was continuously monitored through the testing period. Meanwhile regrowth of microbial populations on the membrane cell was quantified by a unique microbial counting every three to four days. The results showed that both silver-coated membrane (Ag-cM) with uncoated spacer and silver-coated spacer (Ag-cS) with uncoated membrane perforemed better than the unmodified membrane and spacer (Un-MS), in terms of much slower decrease in permeate flux and TDS rejection. However, the effect of silver-coated spacer on antimicrobial activity was more lasting. In the silver-coated spacer test, there was almost no multiplication of cells detected on the membrane during the whole testing period. Besides, the cells adhering to the membrane seemed to lose their activity quickly. According to the RO performance and microbial growth morphology, the nanosilver coating technology is valuable for use in biofouling control in seawater desalination. (C) 2009 Elsevier Ltd. All rights reserved.
Application of TiO(2) photocatalytic oxidation and non-woven membrane filtration hybrid system for degradation of 4-chlorophenol
(2009-09-15)
Horng, Ren-Yang
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Huang, Chihpin
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Chang, Min-Chao
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Shao, Hsin
;
Shiau, Be-Lain
A system coupling photocatalytic oxidation of titanium dioxide particles separated by non-woven membrane for the degradation of 4-chlorophenol in an aqueous solution was studied. Non-woven membranes with three different pore sizes were applied to compare their specific flux and permeate turbidity. The results showed that when the pore size was slightly smaller than secondary particles of photocatalyst, higher specific flux and lower turbidity permeate were obtained. Four different applied fluxes, 0.25, 0.5, 1.0 and 2.0 m(3)/m(2)/d, were used with a 2.0 mu m pore size non-woven membrane in a continuous system. The results revealed that the transmembrane pressure (TMP) was less than 10 kPa in all applied fluxes, due to the formation of a porous dynamic cake layer on the surface of the membrane. Based on the filtration characteristics of non-woven membranes, we found that cake formation, rather than pore blocking or pore narrowing, was the dominant factor. This phenomenon also resulted in permeate turbidity ranging from 0.5 to 1.5 NTU and non-detectable concentration of TiO(2) in the permeate. At the same time the experimental results indicated that the concentrations of TOC and 4-chlorophenol decreased with decreasing applied flux, and that the concentration of chloride ions increased with decreasing applied flux in a 4-chlorophenol photodegradation test. It showed that 4-chlorophenol could be effectively degraded by this hybrid system with lower TMP and stable applied flux.
Characteristic of an innovative TiO(2)/Fe(0) composite for treatment of azo dye
(2007-12-01)
Huang, Chihpin
;
Hsieh, Wen-Pin
;
Pan, Jill Ruhsing
;
Chang, Sue-Min
;
環境工程研究所
The major problem for Fe(0) application is the degradation of performance as time due to the formation of a surface oxide layer and that for TiO(2), is the limit of the efficiency due to the recombination phenomenon. To overcome the problems as well as to improve the performance, our laboratory has been inventing a novel catalyst, which was developed by coating synthesized sol-gel-derived TiO(2) nanoparticles onto the surface of Fe(0). This composite was employed on the degradation of azo dye (Acid Black-24) in the aqueous solution. Results from XPS, XRD and FE-SEM analysis indicated that the laboratory-prepared nanoscale TiO(2)/Fe(0) material is a composite of TiO(2) and Fe(0). The nanoscale TiO(2)/Fe(0) composite with UV irradiation can efficiently decolour and reduce TOC from the simulated wastewater containing Acid Black-24. The efficiency of the TiO(2)/Fe(0) composite with UV irradiation on AB-24 reduction is much more efficient than microscale, and nanoscale Fe(0) and TiO(2) particle (P-25). The evidence shows that TiO(2) particles by sol-gel process were coated on the Fe(0) particles surface, which is attributed to the longer life cycle of Fe(0) reactivity. (c) 2007 Elsevier B.V. All rights reserved.
Characteristic of an innovative TiO2/Fe-0 composite for treatment of azo dye
(2007-12-01)
Huang, Chihpin
;
Hsieh, Wen-Pin
;
Pan, Jill Ruhsing
;
Chang, Sue-Min
;
環境工程研究所
The major problem for Fe-0 application is the degradation of performance as time due to the formation of a surface oxide layer and that for TiO2, is the limit of the efficiency due to the recombination phenomenon. To overcome the problems as well as to improve the performance, our laboratory has been inventing a novel catalyst, which was developed by coating synthesized sol-gel-derived TiO2 nanoparticles onto the surface of Fe-0. This composite was employed on the degradation of azo dye (Acid Black-24) in the aqueous solution. Results from XPS, XRD and FE-SEM analysis indicated that the laboratory-prepared nanoscale TiO2/Fe-0 material is a composite of TiO2 and Fe-0. The nanoscale TiO2/Fe-0 composite with UV irradiation can efficiently decolour and reduce TOC from the simulated wastewater containing Acid Black-24. The efficiency of the TiO2/Fe-0 composite with UV irradiation on AB-24 reduction is much more efficient than microscale, and nanoscale Fe-0 and TiO2 particle (P-25). The evidence shows that TiO2 particles by sol-gel process were coated on the Fe-0 particles surface, which is attributed to the longer life cycle of Fe-0 reactivity. (c) 2007 Elsevier B.V. All rights reserved.
Characteristics of low and high SUVA precursors: Relationships among molecular weight, fluorescence, and chemical composition with DBP formation
(2020-07-20)
Hua, Lap-Cuong
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Chao, Shu-Ju
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Huang, Kochin
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Huang, Chihpin
;
環境工程研究所
Disinfection by-products (DBPs) formed upon water treatment is an emerging issue worldwide. While monitoring of DBP precursors can easily be achieved for high specific UV absorbance (SUVA) organic (>6 L/mg.m), low and extremely low SUVA precursors (<2 L/mg.m) are difficult to monitor or even to predict their DBP formation behaviour. This study investigated the relationships among NOM characteristics, such as molecular weight (MW), fluorescence, and chemical composition, with DBP formation resulting from the chlorination of relatively high and low SUVA precursors. High SUVA precursors were formed by C-rich substances (82-85% of total mass) corresponding with high C/N and C/O (>100 and >5, respectively). Such precursors exhibited the fluorescence of long-wavelength humic-like signal and occurred at a high MW range (>30 kDa). By contrast, low SUVA precursors were either N-rich and/or O-rich substances, associated with much lower carbon content (40-70%). Low SUVA, N-rich precursors particularly also occurred at a high MW region (>100 kDa) and produced a strong protein-like fluorescence signal. When SUVA values of O-rich precursors were extremely low (<1 L/mg.m) they were accompanyied by short-wavelength humic-like fluorescence. During DBP tests, high SUVA produced only high yields of carbonaceous DBPs (e.g trichloromethane, haloacetic acids, haloketones), whereas low SUVA Nrich precursors yielded high levels of both C and NDBPs (e.g. haloacetonenitrile, chloropicrin). By contrast, extremely low SUVA precursors produced significantly lowlevels of both C and NDBPs (total <30 mu g/mgC). Furthermore, 19 of 20 regression models of DBP formation using log-transformed MW gave R-2 = 0.50-0.97. The strong regressions and correlations of NOM characteristics with DBPs in this study provide a better understanding of the influence of precursors characteristics on DBP monitoring, especially for low SUVA NOM. (C) 2020 Elsevier B.V. All rights reserved.
Characteristics of RO foulants in a brackish water desalination plant
(2008-03-01)
Yang, Hui Ling
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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.
Characteristics of soluble microbial products in membrane bioreactor and its effect on membrane fouling
(2010-01-15)
Pan, Jill Ruhsing
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Su, Yuchun
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Huang, Chihpin
;
環境工程研究所
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生物科技學系
In this study, the accumulation and characteristics of soluble microbial products (SMP) in the mixed liquor and the effluent of the membrane bioreactor (MBR) were measured and compared. It was found that the concentration of SMP decreased when the SRT was increased from 10 days to 30 days, and then stabilized as SRT was increased to 60 days. The molecular weight (MW) distributions of SMP indicated that the SMP of larger MW (> 30 kDa) was the most abundant fraction in the MBR. The similar MW distributions of SMP in the mixed liquor and effluent implied that membrane fouling due to SMP in the initial slow fouling stage was not due to size sieving. After the MBR was operated for a period of time, only the SMP of relatively large MW (> 30 kDa) was detected in the mixed liquor. The result indicated that size sieving of SMP occurred only after a cake layer was formed on the membrane surface although the effect was not significant and only worked on larger molecules. The accumulation of hydrophilic components of SMP in the mixed liquor of the bioreactor suggested that the hydrophilic fraction (in carbohydrates) could be the major cause for membrane fouling. (C) 2009 Elsevier B.V. All rights reserved.
Chemical structures of extra- and intra-cellular algogenic organic matters as precursors to the formation of carbonaceous disinfection byproducts
(2017-11-15)
Hua, Lap-Cuong
;
Lin, Jr-Lin
;
Chen, Pei-Chung
;
Huang, Chihpin
;
環境工程研究所
Algal eutrophication in reservoirs is frequently accompanied by a remarkable increase in the concentration of algogenic organic matter (AOM). Because AOM is well-known as an important precursor to disinfection by-products (DBPs) in drinking water, algal eutrophication poses severe concerns for public health. This study aimed to characterize the chemical properties of AOM from two major origins, i.e. extra-(EOM) and intracellular organic matter (IOM), of a commonly found green alga Chlorella sp. as precursors to trihalomethanes (THMs) and haloacetic acids (HAAs). Particularly, the corresponding relation between the chemical functional structure of EOM and IOM and their THM and HAA formation potential (THMFP and HAAFP) was comprehensively investigated. Results show that IOM chiefly comprised of aromatic and other aliphatic protein-like materials (high organic nitrogen content) those have high activity for chlorine substitution (high UV253/UV203 value) due to the high hydroxyl and amide contents in its chemical structures. EOM alternatively exhibited the characteristics of humic-and fulvic-like materials accompanying with high DOC/DON ratio and aromaticity. However, the chemical structure of EOM had a low tendency for chlorine substitution (low UV253/UV203 value); it was also accompanied by a considerable content of carboxylic moisture, which likely resulted in an unfavorable substitution reaction of EOM with chlorine. As a result, the carbonaceous DBP formation potential (C-DBPFP) showed that IOM yielded higher levels of both THMFP and HAAFP than that yielded by EOM.
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.
;
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
;
Huang, Chihpin
;
Chin, Ching-Ju M.
;
Pan, Jill R.
;
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.
Comparison of membrane foulants occurred under different sub-critical flux conditions in a membrane bioreactor (MBR)
(2014-08-01)
Tran-Ngoc-Phu Nguyen
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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.
Dark fermentation production of volatile fatty acids from glucose with biochar amended biological consortium
(2020-05-01)
Lu, Jia-Hsun
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Chen, Chuan
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Huang, Chihpin
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Zhuang, Huichuan
;
Leu, Shao-Yuan
Effects of adding biochars on dark fermentation production of volatile fatty acids (VFAs) from glucose were investigated. Nine biochars were synthesized and applied, together with an activated carbon, as the testing amendment to enhance preferable fermentation. Biochars were porous materials with internal pores and excess surface functional groups, which would lead to enrichment of acetate over butyrate in the VFA production. Biochar coconut and biochar longan shell showed excess functional groups and high bulk internal crystallinity, presented 109.6% and 71.8% enrichments of acetate production, respectively. The syntrophic growth of fermentative bacteria and homoacetogens on biochar surfaces via direct interspecies electron transfer mechanism was assumed to interpret the noted enhanced acetate production. The excess functional groups on biochar surface to facilitate biofilm development and the high crystallinity of biochar bulk to ease electron transfer favored the production of acetate.
Effect of Al(III) speciation on coagulation of highly turbid water
(2008-05-01)
Lin, Jr-Lin
;
Huang, Chihpin
;
Pan, Jill Ruhsing
;
Wang, Dongsheng
;
環境工程研究所
In Taiwan, the turbidity of raw water for fresh water treatments can sometimes reach as high as 40000 NTU due to intensive rainfall, especially in typhoon seasons. In response, water works often apply large quantities of coagulants such as polyaluminium chloride (PACl). In this study, simulated and natural highly turbid water was coagulated with two PACls, a commercial product (PACl-1) and a laboratory product (PACl-E). The Al species distributions of PACl-1 and PACl-E under various pH conditions were determined, and the corresponding coagulation efficiency was evaluated. The PACl-E has a wider range of operational pH, while the efficiency of PACl-1 peaks at around neutral pH. For simulated water up to 5000 NTU, the PACl-E was superior to PACl-1 at low dosage and in the pH range studied. Similar results were discovered with natural water, except that when the turbidity was extremely high, the coagulation efficiency of PACl-E decreased significantly due to the presence of large amounts of organic matter. The coagulation of PACl-E was closely related to the content of polycationic aluminium (Al-13) while that of PACl-1 was dictated by the amount of Al, The sludge from PACl-E coagulation had better dewaterability when the optimum dosage was applied. The experimental results suggest that for natural water up to 5000 NTU, PACl containing high Al-13 species is recommended for coagulation. In cases when the water contains high organic matter, efficient coagulation depends upon enmeshment by amorphous aluminium hydroxide. (C) 2008 Elsevier Ltd. All rights reserved.
Effect of cell integrity on algal destabilization by oxidation-assisted coagulation
(2015-09-04)
Lin, Jr-Lin
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Huang, Chihpin
;
Wang, W. M.
;
環境工程研究所
;
Institute of Environmental Engineering
A hybrid oxidation-coagulation process is commonly adopted to destabilize algae and subsequently improve the removal of algae from water through sedimentation and filtration in water treatment plants (WTPs). Preoxidation is crucial to improving algae removal by a coagulation-sedimentation process. The goal of this study was to investigate the effect of oxidation with NaOCl and ClO2 on the cell integrity of algae (i.e. diatoms) and the destabilization of algae by means of Alum coagulation. The effects of oxidation-assisted coagulation on the performance of sedimentation as well as filtration were evaluated. The results show that ClO2 reduces cell integrity more severely than NaOCl during oxidation. The degradation of chlorophyll a and humic-like substances generated by cells ruptured by ClO2 oxidation is stronger than that by NaOCl oxidation. During oxidation both NaOCl and ClO2 fail to cause significant cell lysis, while cell settleability can be improved markedly by using only ClO2. Preoxidation with ClO2 is more effective in destabilizing the particles and algae when applying Alum coagulation at low dosages. It was found that the residual algae counts in the supernatants are inversely well-correlated to its filterability instead of its residual turbidity. The reduced cell integrity resulting from ClO2 preoxidation effectively improves the performance of coagulation-sedimentation for algae (diatoms) removal and reduces the burden of filtration operation in the WTPs. (C) 2015 Elsevier B.V. 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
;
Lin, Jr-Lin
;
Lee, Wen-Shan
;
Pan, Jill R.
;
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.