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Effect of fouling on removal of trace organic compounds by nanofiltration
S. Hajibabania, A. Verliefde, J. E. Drewes, L. D. Nghiem, J. McDonald, S. Khan,P. Le-Clech
Drinking Water Engineering and Science (DWES) & Discussions (DWESD) , 2011, DOI: 10.5194/dwes-4-71-2011
Abstract: The fate of chemical of concern is not yet fully understood during treatment of impaired waters. The aim of this paper is to assess the impact of different organic-based fouling layers on the removal of a large range of trace organics. Both model and real water samples (mixed with trace organic contaminants at environmental concentration of 2 μg l 1) were used to simulate fouling in nanofiltration under controlled environment. The new and fouled membranes were systematically characterised for surface charge, hydrophobicity and roughness. It was observed that fouling generally reduced the membrane surface charge; however, the alterations of the membrane hydrophobicity and surface roughness were dependent on the foulants composition. The rejection of charged trace organics was observed to be improved due to the increased electrostatic repulsion by fouled membranes and the adsorption of the trace organic chemicals onto organic matters. On the other hand, the removal of nonionic compounds decreased when fouling occurred, due to the presence of cake enhanced concentration polarization. The fouling layer structure was found to play an important role in the rejection of the trace organic compounds.
Preparation and Characterization of Hydrous Zirconium Oxide Formed by Homogeneous Precipitation
Silva, G.L.J.P. da;Silva, M.L.C.P. da;Caetano, Tatiana;
Materials Research , 2002, DOI: 10.1590/S1516-14392002000200011
Abstract: this paper reports on the preparation, characterization and study of the ion exchange behavior of hydrous zirconium oxides formed by homogeneous precipitation from zirconium oxychloride. the precipitants used were obtained by thermal decomposition of urea, sodium nitrite or ammonium carbonate. seven compounds were prepared and characterized by thermal analysis, x-ray diffractometry and by surface area measurements. amorphous forms were obtained in each case, a result that agrees with those obtained by conventional gel precipitation methodology. all these materials present surface area values of >148 m2.g-1, determined after heat treatment at 50 °c. the ion exchange behavior of each hydrous zirconium oxide prepared was studied using k+ as the exchanged species and the results compared with those obtained for hydrous zirconium oxide originally precipitated by the sol gel method.
Preparation and Characterization of Hydrous Zirconium Oxide Formed by Homogeneous Precipitation
Silva G.L.J.P. da,Silva M.L.C.P. da,Caetano Tatiana
Materials Research , 2002,
Abstract: This paper reports on the preparation, characterization and study of the ion exchange behavior of hydrous zirconium oxides formed by homogeneous precipitation from zirconium oxychloride. The precipitants used were obtained by thermal decomposition of urea, sodium nitrite or ammonium carbonate. Seven compounds were prepared and characterized by thermal analysis, X-ray diffractometry and by surface area measurements. Amorphous forms were obtained in each case, a result that agrees with those obtained by conventional gel precipitation methodology. All these materials present surface area values of >148 m2.g-1, determined after heat treatment at 50 °C. The ion exchange behavior of each hydrous zirconium oxide prepared was studied using K+ as the exchanged species and the results compared with those obtained for hydrous zirconium oxide originally precipitated by the sol gel method.
Effect of fouling on removal of trace organic compounds by nanofiltration  [PDF]
S. Hajibabania,A. Verliefde,J. E. Drewes,L. D. Nghiem
Drinking Water Engineering and Science Discussions , 2011, DOI: 10.5194/dwesd-4-117-2011
Abstract: The fate of chemical of concern is not yet fully understood during treatment of impaired waters. The aim of this paper is to assess the impact of different organic-based fouling layers on the removal of a large range of trace organics. Both model and real water samples (mixed with trace organic contaminants at environmental concentration of 2 μg l 1) were used to simulate fouling in NF under controlled environment. The new and fouled membranes were systematically characterised for surface charge, hydrophobicity and roughness. It was observed that fouling generally reduced the membrane surface charge; however, the alterations of the membrane hydrophobicity and surface roughness were dependent on the foulants composition. The rejection of charged trace organics was observed to be improved due to the increased electrostatic repulsion by fouled membranes and the adsorption of the trace organic chemicals onto organic matters. On the other hand, the removal of nonionic compounds decreased when fouling occurred, due to the presence of cake enhanced concentration polarization. The fouling layer structure was found to play an important role in the rejection of the trace organic compounds.
Effect of floc characteristics on nanofiltration membrane fouling
絮体性质对纳滤膜污染的影响

Yu Yang,Zhao Changwei,Wang Yangui,Fan Weihong,Luan Zhaokun,
于洋
,赵长伟,王艳贵,范卫红,栾兆坤

环境工程学报 , 2013,
Abstract: Flocs formed by coagulation process will also affect the performance of membrane filtration. Floc characteristics of coagulants-conventional Al salt (AlCl3) and polyaluminum chloride (PAC) under different dosages were investigated by using a laser diffraction instrument. The results showed that membrane flux decline was deteriorated less than 0.20 mmol/L dosages. With the dosages increasing, membrane flux decline decreased significantly. The flux decline (J/J0) with only humic acid (HA) was 0.65. Adding 0.50 mmol/L AlCl3 and PAC coagulants, the flux declined 0.78 and 0.75, respectively. Cake resistance was more obviously affected by floc size. The bigger floc size is, the better permeability of cake is. The mechanism of nanofiltration membrane fouling was mainly pore blocking by fouling model analysis.
Selective Sorption of Sb(V) Oxoanion by Composite Sorbents Based on Cerium and Zirconium Hydrous Oxides  [PDF]
Eva Mi?tová,Martina Telecká,Helena Parschová,Luděk Jelínek
Ion Exchange Letters , 2008,
Abstract: Composite sorbents based on hydrous oxides of cerium and zirconium were used for selective removal of Sb(V) oxoanion. The effects of pH, concentration of Sb and accompanying anions in the feed solution and kinetic of the sorption were studied. Both CeO2.nH2O/XAD-7 and ZrO-PAN sorbents showed maximum sorption of Sb(V) oxoanions at pH of 3.5. Sorbent CeO2.nH2O/XAD-7 showed higher removal efficiency than ZrO-PAN. In both cases, increased concentration of sulfates and chlorides in the feed solution caused a decrease of Sb(V) removal
Selective sorption of Sb(III) oxoanion by composite sorbents based on cerium and zirconium hydrous oxides  [PDF]
Eva Mi?tová,Martina Telecká,Helena Parschová,Luděk Jelínek
Ion Exchange Letters , 2009,
Abstract: Composite sorbents based on hydrous oxides of cerium and zirconium were used for selective removal of Sb(III) oxoanion. The effects of pH, concentration of Sb and accompanying anions in the feed solution and kinetic of the sorption were studied. Both CeO2.nH2O/XAD-7 and ZrO-PAN sorbents showed similar sorption capacity at all pH value which was studied. Sorbent CeO2.nH2O/XAD-7 showed higher removal efficiency than ZrO-PAN. In both cases, increased concentration of sulfates and chlorides in the feed solution caused a decrease of Sb(III) removal.
Analysis of membrane fouling genesis in nanofiltration process for advanced treatment of dyeing and finishing wastewater
染整废水深度处理纳滤工艺膜污染成因分析

Cao Xiao-Bing,Li Tao,Zhou Liu,Yang Hai-Jun,Wang Xiao,
Cao XB
,Li T,Zhou L,Yang HJ,Wang X

环境科学 , 2012,
Abstract: In order to investigate the types and genesis of membrane fouling of nanofiltration desalination system treating dyeing and finishing wastewater of cotton knit textile, comprehensive analysis, using ICP-AES, SEM-EDX, FTIR, TGA, high optical microscope and XRF, was carried out based on tests of influent water quality, and tests of the membrane fouling states of different processes and tests of membrane cleaning. The results showed that the types of membrane fouling included inorganic fouling, organic fouling and microbial fouling. The mass percents of bound water, organic substance and inorganic substance of dry foulants, dried at 105 degrees C, were 8.2%, 41.0% and 50.8% respectively. Ferric salt was the most serious inorganic fouling salt, and the main functional groups, found from organic foulants, were -OH, -CH and -C =C. Several kinds of protozoa were found from the membrane foulants as well as metazoan. The analysis of short-term and long-term membrane fouling indicated that it need a long time cumulative effect for the formation of organic fouling and microbial fouling. The results of NF cleaning tests showed that the mainly reason lead to the decline of membrane flux were organic fouling and microbial fouling, which took 53.3%.
Fouling of nanofiltration membrane by e uent organic matter: Characterization using di erent organic fractions in wastewater

ZHANG Liqing,WANG Lei,ZHANG Gang,WANG Xudong,

环境科学学报(英文版) , 2009,
Abstract: The UF membrane with molecular weight cuto (MWCO) ranging from 2 to 100 kDa and XAD-8 resin were employed to identify the characteristic of molecular weight (MW) distribution of wastewater e uent organic matter (EfOM) in terms of TOC and UV254, as well as the amounts of the hydrophilic/hydrophobic organic fractions in di erent MW ranges. Then, the nanofiltration (NF) membrane fouling experiments were carried out using the above fractionated water to investigate the e ect of MW distribution and hydrophilic/hydrophobic characteristics of EfOM on the membrane flux decline using the fractionated water samples. The experimental results have shown that 45.61% of the total organics belongs to the low MW one, among which the percentage of the hydrophilic organics with low MW (less than 2 kDa) was up to 28.07%, while that of the hydrophobic organics was 17.54%. In particular, the hydrophilic fraction was found to be the most abundant fraction in the e uents. MW distribution has a significant e ect on the membrane fouling. When the MWwas less than 30 kDa, the lower the MW, the larger was the specific flux decline, while in the case of MW higher than 30 kDa, the higher the MW, the larger was the specific flux decline, and the decline degree of low MW organics was larger than the high MW one. With the same MW distribution range, specific flux decline of the hydrophilic organic was considerably slower than that of the hydrophobic organic, which indicated that the hydrophobic organic fractions dominantly contribute to the flux decline.
Fouling Reasons and Cleaning Methods of Nanofiltration Membrane Filtrated with the Effluent of Membrane Bioreactor
纳滤膜过滤MBR出水的污染原因与清洗方法

CHEN Jian-hua,HUANG Xia,
陈健华
,黄霞

环境科学 , 2008,
Abstract: In order to investigate the fouling reasons and cleaning methods of nanofiltration membrane fouled with the effluent of membrane bioreactor (MBR), FEG-SEM-EDS, FTIR, AFM and contact angle system, were applied to analyze the membrane fouling layer. The results showed that, the foulants included both organic and inorganic substances, which contained phosphorous (P) and magnesium (Mg). After investigations of membrane surfaces through different cleaning steps, it was showed that critic acid cleaning could remove Mg and most of P, which were inorganic; and subsequent sodium hydroxide cleaning could remove the residual P, which probably came from organic acid, organic phosphorous or protein. The roughness increased from 79.5 nm to 111.2 nm with fouling, but the hydrophilicity didn't change obviously according to the contact angle from 55.6° to 62.1°. But after acid cleaning, the roughness decreased to 51.9 nm and the contact angle changed to be 96.0°, which showed the organic foulants were exposed and the surface changed to be hydrophobic. And after subsequent alkali cleaning, the roughness and the hydrophilicity were both close to those of the new membrane. These results concluded that acid cleaning followed by alkali cleaning could remove most of the foulants. It was also suggested that organic matters fouled the membrane in the initial stage, and inorganic matters aggravated the membrane fouling subsequently.
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