A novel thermally induced graft polymerization technique was used to modify a polyvinylidene fluoride （PVDF） hollow fibre microfiltration membrane. An artificial neural network （ANN） was applied to optimize the pr...A novel thermally induced graft polymerization technique was used to modify a polyvinylidene fluoride （PVDF） hollow fibre microfiltration membrane. An artificial neural network （ANN） was applied to optimize the prepared condition of the membrane. The optimized dosing of acrylic acid （AA）, acrylamide （AM）, N, N＇- methylenebisacrylamide （NMBA） and potassium persulphate （KSP） designed by ANN was that AA was 40.63 ml/L; AM acted as 6.25 g/L; NMBA was 1.72 g/L and KSP was 1.5 g/L, respectively. The thermal stability of the PVDF modified hollow fibre membrane （PVDF-PAA） was investigated by thermogravimetric （TG） and differential scanning calorimetry （DSC） analysis. The polycrystallinity of the PVDF-PAA membrane was evaluated by X-ray diffraction （XRD） analysis. The complex formation of the modified membrane was ascertained by Fourier transform infrared spectroscopy （FTIR）. The morphology of the PVDF-PAA membrane was studied by environmental scanning electron microscopy （ESEM）. The surface compositions of the membrane were analyzed by X-ray photoelectron spectroscopy （XPS）. The adsorption capacity of Cu^2＋ ion on the PVDF-PAA hollow fibre membrane was also investigated.展开更多
Precluding the excessive lipoproteins from plasma rapidly and effectively is highly needed for biomedical detection and reducing plasma product scrap in blood donation stations.The current centrifugation procedure is ...Precluding the excessive lipoproteins from plasma rapidly and effectively is highly needed for biomedical detection and reducing plasma product scrap in blood donation stations.The current centrifugation procedure is high-cost and time-consuming.Herein,we fabricated an anionic microfiltration polyethersulfone(PES)membrane modified by interface swelling and implanting of acrylic acid(AA)for screening out large particle lipoprotein chylomicron(CM)and adsorbing cationic very low-density lipoproteins(VLDL).To improve the separation efficiency,a two-stage filtration through carboxylated polyethersulfone microfiltration membranes with the mean pore size of 0.45 and 0.22μm respectively were conducted.Attenuated total reflection Fourier transform infrared technique(ATR-FTIR),water contact angle(WCA),Zeta potential and scanning electron microscope(SEM)were employed to characterize the modified membrane.To test the effectiveness of this membrane,plasma flux and concentration variation of plasma components were examined to study the purification effectiveness.Furthermore,the hemocompatibility of modified membranes was tested to confirm its practicability on bloodcontacting materials.The carboxylated polyethersulfone microfiltration membrane shows its promising potential application to purify chylous plasma.展开更多
Membrane microfiltration fermentation (MMF) with cell recycling was successfully applied to the production of glucose oxidase (GOD). A plate microfiltration module was found suitable for such purpose. By feeding whole...Membrane microfiltration fermentation (MMF) with cell recycling was successfully applied to the production of glucose oxidase (GOD). A plate microfiltration module was found suitable for such purpose. By feeding whole medium in MMF, the productivity of GOD was much higher than that by feeding glucose alone. With increasing dilution rate the enzyme productivity increased and average enzyme activity decreased. The enzyme productivity of MMF under D = 0.12h-1 and 0.20h-1 were 3871 and 3945U·h-1 respectively, which was about 3 times as that of batch fermentation (BF) and the average enzyme activity was still as high as STU·mL-1 under D = 0.12h-1. The relative efficiency of MMF applied to low yield strain was higher than that applied to high yield strain.展开更多
Microfiltration membrane technology has been widely used in various industries for solid-liquid separation. However, pore clogging remains a persistent challenge. This study employs (CFD) and discrete element method (...Microfiltration membrane technology has been widely used in various industries for solid-liquid separation. However, pore clogging remains a persistent challenge. This study employs (CFD) and discrete element method (DEM) models to enhance our understanding of microfiltration membrane clogging. The models were validated by comparing them to experimental data, demonstrating reasonable consistency. Subsequently, a parametric study was conducted on a cross-flow model, exploring the influence of key parameters on clogging. Findings show that clogging is a complex phenomenon affected by various factors. The mean inlet velocity and transmembrane flux were found to directly impact clogging, while the confinement ratio and cosine of the membrane pore entrance angle had an inverse relationship with it. Two clog types were identified: internal (inside the pore) and external (arching at the pore entrance), with the confinement ratio determining the type. This study introduced a dimensionless number as a quantitative clogging indicator based on transmembrane flux, Reynolds number, filtration time, entrance angle cosine, and confinement ratio. While this hypothesis held true in simulations, future studies should explore variations in clogging indicators, and improved modeling of clogging characteristics. Calibration between numerical and physical times and consideration of particle volume fraction will enhance understanding.展开更多
The advancement of direct seawater electrolysis is a significant step towards sustainable hydrogen production,addressing the critical need for renewable energy sources and efficient resource utilization.However,direct...The advancement of direct seawater electrolysis is a significant step towards sustainable hydrogen production,addressing the critical need for renewable energy sources and efficient resource utilization.However,direct seawater electrolysis has to face several challenges posed by the corrosiveness of highly concentrated chloride and the competitive chlorine evolution reaction(ClER).To overcome these issues,we designed a novel NiP_(2)@CoP electrocatalyst on a porous titanium microfiltration(Ti MF)membrane.The obtained bifunctional NiP_(2)@CoP catalyst outperforms the Pt/C and IrO_(2),as evidenced by its low overpotentials of 192 and 425 mV at a current density of 500 mA·cm^(-2) for hydrogen evolution reaction(HER)and oxygen evolution reaction(OER)in alkaline seawater(1 M KOH+0.5 M NaCl),respectively.Especially,only 231 and 569 mV overpotentials are required at the current density of 1500 mA·cm^(-2) towards HER and OER in alkaline seawater,respectively.More importantly,no ClER was observed,demonstrating its excellent selectivity to OER.The selection of porous Ti MF membrane as an electrode substrate further enhances the performance by providing a robust structure that promotes the fast generation and release of gas bubbles.Our promising outcomes obtained with NiP_(2)@CoP catalysts on Ti MF support,therefore,pave the way for the commercial viability of direct seawater electrolysis technologies at industrial-level current densities.展开更多
A study on the membrane coalescence demulsification was carried out with four working systems of water/n-butyl alcohol, water/n-octanol, water/30% TBP(in kerosene) and water/kerosene. The membranes made of polytetrafl...A study on the membrane coalescence demulsification was carried out with four working systems of water/n-butyl alcohol, water/n-octanol, water/30% TBP(in kerosene) and water/kerosene. The membranes made of polytetrafluoroethylene (PTFE) with 1.0μm pore size were used. The results indicated that the excellent demulsification efficiency for emulsions with various oil contents was obtained. A conductivity probe was used to study the demulsification mechanism. An electrode probe was designed and used to determine the oil content near the membrane surface. The obtained data showed that the oil content in the permeated stream was much higher than that in the feed emulsion. A physical mechanism to explain the membrane demulsification was put forward.展开更多
This paper reports a study on the role of fluid flow pattern and dynamic pressure on the permeate flux through a micro filtration membrane in laboratory scale.For this purpose,a dead-end membrane cell equipped with a ...This paper reports a study on the role of fluid flow pattern and dynamic pressure on the permeate flux through a micro filtration membrane in laboratory scale.For this purpose,a dead-end membrane cell equipped with a marine type impeller was used.The impeller was set to rotate in the clockwise and counter clockwise directions with the same angular velocities in order to illustrate the effect of rotation direction on permeate flux.Consequently, permeate fluxes were measured at various impeller rotational speeds.The computational fluid dynamics（CFD）predicted dynamic pressure was related to the fluxes obtained in the experiments.Using the CFD modeling,it is proven that the change in dynamic pressure upon the membrane surface has direct effect on the permeate flux.展开更多
The degradation of fulvic acid（FA） by nanoparticle TiO2 in a submerged membrane photocatalysis（SMPC） reactor was studied. In this reactor, photocatalytic oxidation and membrane separation co-occured. The continuou...The degradation of fulvic acid（FA） by nanoparticle TiO2 in a submerged membrane photocatalysis（SMPC） reactor was studied. In this reactor, photocatalytic oxidation and membrane separation co-occured. The continuous air supplier provided O2 for the photocatalytical reaction and mixed the solution through an airflow controller. The particle TiO2 could automatically settle due to gravity without particle agglomeration so it could be easily separated by microfiltration（MF） membrane. It was efficient to maintain high flux of membranes. The effects of operational parameters on the photocatalytic oxidation rate of FA were investigated. Results indicated that photocatalyst at 0.5 g/L and airflow at 0.06 m^3/h were the optimum condition for the removal of fulvic acid, the removal efficiency was higher in acid media than that in alkaline media. The effects of different filtration duration on permeate flux rate of MF with P25 powder and with nanoparticle TiO2 were compared. Experimental results indicated that the permeate flux rate of MF was improved and the membrane fouling phenomenon was reduced with the addition of nanoparticle TiO2 catalyst compared with conventional P25 powder. Therefore, this submerged membrane photocatalysis reactor can faciliate potential application of photocatalytic oxidation process in drinking water treatment.展开更多
The oily wastewater generated from pretreatment unit of electrocoating industry contains oils, phosphate, organic solvents, and surfactants. In order to improve the removal efficiencies of phosphate and oils, to mitig...The oily wastewater generated from pretreatment unit of electrocoating industry contains oils, phosphate, organic solvents, and surfactants. In order to improve the removal efficiencies of phosphate and oils, to mitigate the membrane fouling, coagulation for ceramic membrane microfiltration of oily wastewater was performed. The results of filtration tests show that the membrane fouling decreased and the permeate flux and quality increased with coagulation as pretreatment. At the coagulant Ca （OH）2 dosage of 900 mg/L, the removal efficiency of phosphate was increased from 46.4% without coagulation to 99.6%; the removal of COD and oils were 97.0% and 99.8%, respectively. And the permeate flux was about 70% greater than that when Ca（OH）2 was not used. The permeate obtained from coagulation and microfiltration can be reused as make-up water, and the recommended operation conditions for pilot and industrial application are transmembrane pressure of 0.10 MPa and cross-flow velocity of 5 m/s. The comparison results show that 0.2 μm ZrO2 microfilter with coagulation could be used to perform the filtration rather than conventional ultrafilter, with very substantial gain in flux and removal efficiency of phosphate.展开更多
Experimental investigation of the microfiltration （MF） using a revolving cross-flow membrane filter was performed under the condition of constant pressure difference, and different flat membranes made of polyvinylid...Experimental investigation of the microfiltration （MF） using a revolving cross-flow membrane filter was performed under the condition of constant pressure difference, and different flat membranes made of polyvinylidene fluoride （PVDF, 0.1 μm）, cellulose acetate （CA, 0.22 μm）, sulfonated polyethersulfone （SPES, 0.22 μm） and polyamide （PA, 0.45 μm）, respectively, were used in filtration experiments. The dependence of the filtrate mass of the cross-flow MF on time was measured on-line. The experimental results showed that the effect of the cross-flow on high viscosity medium was more significant than that on the low viscosity one.展开更多
In order to understand the effect of low temperature on the formation process of aerobic granules and contaminants removal characteristics,the aerobic granules-membrane bioreactor (AGS-MBR) has been started up and ope...In order to understand the effect of low temperature on the formation process of aerobic granules and contaminants removal characteristics,the aerobic granules-membrane bioreactor (AGS-MBR) has been started up and operated at low temperature using the carbon resource of sodium acetate. Aerobic granules cultivated in AGS-MBR possess smooth surface and compact structure in morphology as well as better settling property and higher biomass after 38 days. The average parameters of aerobic granules are: diameter 3. 1 mm,wet density 1. 041 g/mL,sludge volume index 42. 35 mL/g and settling velocity 20. 6 - 45. 2 cm/min. During the start-up of AGS-MBR,the respectively average contaminants removal efficiencies at low temperature are 91. 9% for chemical oxygen demand (COD) ,89. 2% for NH4 + -N and 86. 3% for PO43- -P,and the overgrowth of filamentous bacteria has been well controlled. In addition,the hollow fiber microfiltration (MF) membrane fouling is light and the regime membrane layer is capable of enhancing membrane filtration as well as the average growth of trans-membrane pressure (TMP) is 1. 07 kPa/d. Compared with the conventional cultivation of aerobic granules,the sludge granulation time significantly decreases from 73 days to 38 days by the application of microfiltration membrane at low temperature.展开更多
Structural regular polyaniline was synthesized via a modified-chemical oxidative polymerization reaction. Highly hydrophilic polyaniline(PANi) and polyaniline-poly(vinylidene fluoride) blend(PANi-PVDF) membranes were ...Structural regular polyaniline was synthesized via a modified-chemical oxidative polymerization reaction. Highly hydrophilic polyaniline(PANi) and polyaniline-poly(vinylidene fluoride) blend(PANi-PVDF) membranes were prepared by solution casting and phase inversion techniques. Both of the mechanical and filtration properties of the membranes depend on the polymer composition and doping level of the blends. The elasticity of the membrane is greatly improved upon introducing poly(vinylidene fluoride) into the blend. The water permeability of the blend membranes is further enhanced when the membranes are doped with hydrochloric acid. The PANi-PVDF blend membranes are capable of recovering metallic gold from the acid/halide leaching streams spontaneous and sustainably, and are promising candidates for wastewater treatments in electronic industries.展开更多
To understand the adsorption behavior of endocrine disrupting chemicals（EDCs） is important for enhancing the treatment performance and preventing potential secondary pollution caused by EDCs desorption in a microfil...To understand the adsorption behavior of endocrine disrupting chemicals（EDCs） is important for enhancing the treatment performance and preventing potential secondary pollution caused by EDCs desorption in a microfiltration system. The dynamic adsorption of four representative EDCs, namely estriol（E3）, 17β-estradiol（E2）, 17α-ethynylestradiol（EE2）, and 4-nonylphenol（4-NP） in a microfiltration system was investigated using the Thomas＇ model.The product of the equilibrium constant and the total adsorption capacity of the membrane,Ka, for E3, E2, EE2, and 4-NP were 4.91, 9.78, 15.6, and 826, respectively, strongly correlating with the compound octanol–water partition coefficient（KOW）. Adsorption appeared to be enhanced when organic fouling formed on the surface of membrane, indicating the role of an additional adsorption column for EDCs acted by a fouling layer in microfiltration. Results of a comparison between the Ka values for clean membrane and fouled membrane illustrated that the significant contribution made by fouling layers may be attributed to the foulant layer＇s hydrophobicity（in the case of calcium humate layer） and thickness（in the case of calcium alginate layer）. This study provided a novel perspective to quantitatively analyze the dynamic adsorption behavior of trace pollutants in membrane process.展开更多
This paper presents a method that is capable of predicting pore structure of coal-based microfiltration carbon membranes. The tubular carbon membranes are prepared from coal samples with different particle size and di...This paper presents a method that is capable of predicting pore structure of coal-based microfiltration carbon membranes. The tubular carbon membranes are prepared from coal samples with different particle size and distribution by using the extrusion method. According to the relationship between properties of coal samples (particle size and distribution) and pore structure parameters of coal-based carbon membranes, the experiential equations of average pore size and porosity are concluded, and the change law of pore size distribution curve is also summarized. The results show pore structure properties of coal-based carbon membranes can be exactly predicted for different separation requirements by adjusting coal particle size and distribution, which allows us to minimize cost and time consuming experiments in the development of coal-based microfiltration membranes.展开更多
Forward osmotic membrane bioreactor is an emerging technology that combines the advantages of forward osmosis and conventional membrane bioreactor. In this paper, bisphenol A removal by using a forward osmotic membran...Forward osmotic membrane bioreactor is an emerging technology that combines the advantages of forward osmosis and conventional membrane bioreactor. In this paper, bisphenol A removal by using a forward osmotic membrane bioreactor and a conventional mem- brane bioreactor that shared one biologic reactor was studied. The total removal rate of bisphenol A by the conventional membrane bioreactor and forward osmotic membrane bioreactor was as high as 93.9% and 98%, respectively. Biodegradation plays a dominant role in the total removal of bisphenol A in both processes. In comparison of membrane rejection, the forward osmosis membrane can remove approximately 70% bisphenol A from the feed, much higher than that of the microfiltration membrane （below 10%）. Forward osmosis membrane bioreactor should be operated with its BPA loading rate under 0.08 mg. g-1. d-1 to guarantee the effluent bisphenol A concentration less thanlO μg·L-1.展开更多
In the present study the membrane fouling in microfiltraiton used for cell harvesting in a deadend system has been investigated. Experimental results were analysed in terms of existing membrane filtration models and m...In the present study the membrane fouling in microfiltraiton used for cell harvesting in a deadend system has been investigated. Experimental results were analysed in terms of existing membrane filtration models and membrane resistances. The cake filtration model (CFM) and standard blocking model (SBM) have been considered in this study.Various membrane resistances were determined at different processing time, feed concentration and stirring speed. Resistances to permeation in this system include filter medium, pore blocking, adsorption, cake layer and concentration polarization.展开更多
In this research,the treatability of solids from sanitary landfill leachate by microfiltration membrane was investigated and the fouling of the membrane was carefully studied.Continuous microfiltration process was car...In this research,the treatability of solids from sanitary landfill leachate by microfiltration membrane was investigated and the fouling of the membrane was carefully studied.Continuous microfiltration process was carried out for 21 h in experimental system involved coagulation with Moringa oleifera followed by filtration using submerged hollow fibre microfiltration membrane (MFM).Coagulation with M.Oleifera,air diffusers and back flush technique were used for preventing or alleviating fouling of the membrane.The hollow fibre MFM showed high removals of 98%,91% and 99% for turbidity,colour and total suspended solids respectively.It was obtained at the beginning of the filtration.However,quality of the filtrate rapidly declined during the filtration process.Fouling was found to proceed according to the classical cake filtration model.Coagulation with M.Oleifera as well as the back-flush technique could not fully restore the deterioration occurred to the membrane.展开更多
文摘A novel thermally induced graft polymerization technique was used to modify a polyvinylidene fluoride （PVDF） hollow fibre microfiltration membrane. An artificial neural network （ANN） was applied to optimize the prepared condition of the membrane. The optimized dosing of acrylic acid （AA）, acrylamide （AM）, N, N＇- methylenebisacrylamide （NMBA） and potassium persulphate （KSP） designed by ANN was that AA was 40.63 ml/L; AM acted as 6.25 g/L; NMBA was 1.72 g/L and KSP was 1.5 g/L, respectively. The thermal stability of the PVDF modified hollow fibre membrane （PVDF-PAA） was investigated by thermogravimetric （TG） and differential scanning calorimetry （DSC） analysis. The polycrystallinity of the PVDF-PAA membrane was evaluated by X-ray diffraction （XRD） analysis. The complex formation of the modified membrane was ascertained by Fourier transform infrared spectroscopy （FTIR）. The morphology of the PVDF-PAA membrane was studied by environmental scanning electron microscopy （ESEM）. The surface compositions of the membrane were analyzed by X-ray photoelectron spectroscopy （XPS）. The adsorption capacity of Cu^2＋ ion on the PVDF-PAA hollow fibre membrane was also investigated.
基金financially supported by Natural Science Foundation of Ningbo City(2018A610026)Zhejiang Provincial Natural Science Foundation of China for Distinguished Young Scholars(LR20E030002)+1 种基金Ten thousand plan-high level talents special support plan of Zhejiang province,China(ZJWR0108020)Youth Innovation Promotion Association of Chinese Academy of Science(2014258)。
文摘Precluding the excessive lipoproteins from plasma rapidly and effectively is highly needed for biomedical detection and reducing plasma product scrap in blood donation stations.The current centrifugation procedure is high-cost and time-consuming.Herein,we fabricated an anionic microfiltration polyethersulfone(PES)membrane modified by interface swelling and implanting of acrylic acid(AA)for screening out large particle lipoprotein chylomicron(CM)and adsorbing cationic very low-density lipoproteins(VLDL).To improve the separation efficiency,a two-stage filtration through carboxylated polyethersulfone microfiltration membranes with the mean pore size of 0.45 and 0.22μm respectively were conducted.Attenuated total reflection Fourier transform infrared technique(ATR-FTIR),water contact angle(WCA),Zeta potential and scanning electron microscope(SEM)were employed to characterize the modified membrane.To test the effectiveness of this membrane,plasma flux and concentration variation of plasma components were examined to study the purification effectiveness.Furthermore,the hemocompatibility of modified membranes was tested to confirm its practicability on bloodcontacting materials.The carboxylated polyethersulfone microfiltration membrane shows its promising potential application to purify chylous plasma.
基金Supported by the National Natural Science Foundation of China(No.39170020).
文摘Membrane microfiltration fermentation (MMF) with cell recycling was successfully applied to the production of glucose oxidase (GOD). A plate microfiltration module was found suitable for such purpose. By feeding whole medium in MMF, the productivity of GOD was much higher than that by feeding glucose alone. With increasing dilution rate the enzyme productivity increased and average enzyme activity decreased. The enzyme productivity of MMF under D = 0.12h-1 and 0.20h-1 were 3871 and 3945U·h-1 respectively, which was about 3 times as that of batch fermentation (BF) and the average enzyme activity was still as high as STU·mL-1 under D = 0.12h-1. The relative efficiency of MMF applied to low yield strain was higher than that applied to high yield strain.
文摘Microfiltration membrane technology has been widely used in various industries for solid-liquid separation. However, pore clogging remains a persistent challenge. This study employs (CFD) and discrete element method (DEM) models to enhance our understanding of microfiltration membrane clogging. The models were validated by comparing them to experimental data, demonstrating reasonable consistency. Subsequently, a parametric study was conducted on a cross-flow model, exploring the influence of key parameters on clogging. Findings show that clogging is a complex phenomenon affected by various factors. The mean inlet velocity and transmembrane flux were found to directly impact clogging, while the confinement ratio and cosine of the membrane pore entrance angle had an inverse relationship with it. Two clog types were identified: internal (inside the pore) and external (arching at the pore entrance), with the confinement ratio determining the type. This study introduced a dimensionless number as a quantitative clogging indicator based on transmembrane flux, Reynolds number, filtration time, entrance angle cosine, and confinement ratio. While this hypothesis held true in simulations, future studies should explore variations in clogging indicators, and improved modeling of clogging characteristics. Calibration between numerical and physical times and consideration of particle volume fraction will enhance understanding.
基金support of the Natural Science Foundation of Tianjin for Distinguished Young Scholar(No.20JCJQJC00150)Basic Research Program of Jiangsu Province(No.BK20241845)+2 种基金the National Natural Science Foundation of China(No.21872104)Tianjin Research Innovation Project for Postgraduate Students(No.2022BKY135)the National Key Research and Development Program of China(Nos.2020YFA0211003 and 2020YFA0211002).
文摘The advancement of direct seawater electrolysis is a significant step towards sustainable hydrogen production,addressing the critical need for renewable energy sources and efficient resource utilization.However,direct seawater electrolysis has to face several challenges posed by the corrosiveness of highly concentrated chloride and the competitive chlorine evolution reaction(ClER).To overcome these issues,we designed a novel NiP_(2)@CoP electrocatalyst on a porous titanium microfiltration(Ti MF)membrane.The obtained bifunctional NiP_(2)@CoP catalyst outperforms the Pt/C and IrO_(2),as evidenced by its low overpotentials of 192 and 425 mV at a current density of 500 mA·cm^(-2) for hydrogen evolution reaction(HER)and oxygen evolution reaction(OER)in alkaline seawater(1 M KOH+0.5 M NaCl),respectively.Especially,only 231 and 569 mV overpotentials are required at the current density of 1500 mA·cm^(-2) towards HER and OER in alkaline seawater,respectively.More importantly,no ClER was observed,demonstrating its excellent selectivity to OER.The selection of porous Ti MF membrane as an electrode substrate further enhances the performance by providing a robust structure that promotes the fast generation and release of gas bubbles.Our promising outcomes obtained with NiP_(2)@CoP catalysts on Ti MF support,therefore,pave the way for the commercial viability of direct seawater electrolysis technologies at industrial-level current densities.
基金Supported by the National Natural Science Foundation of China(No.29976021).
文摘A study on the membrane coalescence demulsification was carried out with four working systems of water/n-butyl alcohol, water/n-octanol, water/30% TBP(in kerosene) and water/kerosene. The membranes made of polytetrafluoroethylene (PTFE) with 1.0μm pore size were used. The results indicated that the excellent demulsification efficiency for emulsions with various oil contents was obtained. A conductivity probe was used to study the demulsification mechanism. An electrode probe was designed and used to determine the oil content near the membrane surface. The obtained data showed that the oil content in the permeated stream was much higher than that in the feed emulsion. A physical mechanism to explain the membrane demulsification was put forward.
文摘This paper reports a study on the role of fluid flow pattern and dynamic pressure on the permeate flux through a micro filtration membrane in laboratory scale.For this purpose,a dead-end membrane cell equipped with a marine type impeller was used.The impeller was set to rotate in the clockwise and counter clockwise directions with the same angular velocities in order to illustrate the effect of rotation direction on permeate flux.Consequently, permeate fluxes were measured at various impeller rotational speeds.The computational fluid dynamics（CFD）predicted dynamic pressure was related to the fluxes obtained in the experiments.Using the CFD modeling,it is proven that the change in dynamic pressure upon the membrane surface has direct effect on the permeate flux.
文摘The degradation of fulvic acid（FA） by nanoparticle TiO2 in a submerged membrane photocatalysis（SMPC） reactor was studied. In this reactor, photocatalytic oxidation and membrane separation co-occured. The continuous air supplier provided O2 for the photocatalytical reaction and mixed the solution through an airflow controller. The particle TiO2 could automatically settle due to gravity without particle agglomeration so it could be easily separated by microfiltration（MF） membrane. It was efficient to maintain high flux of membranes. The effects of operational parameters on the photocatalytic oxidation rate of FA were investigated. Results indicated that photocatalyst at 0.5 g/L and airflow at 0.06 m^3/h were the optimum condition for the removal of fulvic acid, the removal efficiency was higher in acid media than that in alkaline media. The effects of different filtration duration on permeate flux rate of MF with P25 powder and with nanoparticle TiO2 were compared. Experimental results indicated that the permeate flux rate of MF was improved and the membrane fouling phenomenon was reduced with the addition of nanoparticle TiO2 catalyst compared with conventional P25 powder. Therefore, this submerged membrane photocatalysis reactor can faciliate potential application of photocatalytic oxidation process in drinking water treatment.
文摘The oily wastewater generated from pretreatment unit of electrocoating industry contains oils, phosphate, organic solvents, and surfactants. In order to improve the removal efficiencies of phosphate and oils, to mitigate the membrane fouling, coagulation for ceramic membrane microfiltration of oily wastewater was performed. The results of filtration tests show that the membrane fouling decreased and the permeate flux and quality increased with coagulation as pretreatment. At the coagulant Ca （OH）2 dosage of 900 mg/L, the removal efficiency of phosphate was increased from 46.4% without coagulation to 99.6%; the removal of COD and oils were 97.0% and 99.8%, respectively. And the permeate flux was about 70% greater than that when Ca（OH）2 was not used. The permeate obtained from coagulation and microfiltration can be reused as make-up water, and the recommended operation conditions for pilot and industrial application are transmembrane pressure of 0.10 MPa and cross-flow velocity of 5 m/s. The comparison results show that 0.2 μm ZrO2 microfilter with coagulation could be used to perform the filtration rather than conventional ultrafilter, with very substantial gain in flux and removal efficiency of phosphate.
基金Supported by the State Key Development Program for Basic Research of China(2003CB615705)
文摘Experimental investigation of the microfiltration （MF） using a revolving cross-flow membrane filter was performed under the condition of constant pressure difference, and different flat membranes made of polyvinylidene fluoride （PVDF, 0.1 μm）, cellulose acetate （CA, 0.22 μm）, sulfonated polyethersulfone （SPES, 0.22 μm） and polyamide （PA, 0.45 μm）, respectively, were used in filtration experiments. The dependence of the filtrate mass of the cross-flow MF on time was measured on-line. The experimental results showed that the effect of the cross-flow on high viscosity medium was more significant than that on the low viscosity one.
基金Sponsored by the National High Technology Research and Development Program of China (863 Program,Grant No.2008AA06Z304)State Water Pollution Control and Harnessing of the Major Projects (Grant No.2009ZX07424-005)International Cooperation Program (Grant No.2010DFA92460)
文摘In order to understand the effect of low temperature on the formation process of aerobic granules and contaminants removal characteristics,the aerobic granules-membrane bioreactor (AGS-MBR) has been started up and operated at low temperature using the carbon resource of sodium acetate. Aerobic granules cultivated in AGS-MBR possess smooth surface and compact structure in morphology as well as better settling property and higher biomass after 38 days. The average parameters of aerobic granules are: diameter 3. 1 mm,wet density 1. 041 g/mL,sludge volume index 42. 35 mL/g and settling velocity 20. 6 - 45. 2 cm/min. During the start-up of AGS-MBR,the respectively average contaminants removal efficiencies at low temperature are 91. 9% for chemical oxygen demand (COD) ,89. 2% for NH4 + -N and 86. 3% for PO43- -P,and the overgrowth of filamentous bacteria has been well controlled. In addition,the hollow fiber microfiltration (MF) membrane fouling is light and the regime membrane layer is capable of enhancing membrane filtration as well as the average growth of trans-membrane pressure (TMP) is 1. 07 kPa/d. Compared with the conventional cultivation of aerobic granules,the sludge granulation time significantly decreases from 73 days to 38 days by the application of microfiltration membrane at low temperature.
基金supported by the Public Welfare Technology Applied Research Projects of Zhejiang Province (2014C33G3220001)the National Natural Science Foundation of China (61674153, 51525103, 61504154, 11474295)+3 种基金the Youth Innovation Promotion Association of the Chinese Academy of SciencesNatural Science Foundation of Zhejiang Province (LR17E020001)Ningbo Science and Technology Innovation Team (2015B11001)Ningbo International Cooperation Projects (2015B11027)
文摘Structural regular polyaniline was synthesized via a modified-chemical oxidative polymerization reaction. Highly hydrophilic polyaniline(PANi) and polyaniline-poly(vinylidene fluoride) blend(PANi-PVDF) membranes were prepared by solution casting and phase inversion techniques. Both of the mechanical and filtration properties of the membranes depend on the polymer composition and doping level of the blends. The elasticity of the membrane is greatly improved upon introducing poly(vinylidene fluoride) into the blend. The water permeability of the blend membranes is further enhanced when the membranes are doped with hydrochloric acid. The PANi-PVDF blend membranes are capable of recovering metallic gold from the acid/halide leaching streams spontaneous and sustainably, and are promising candidates for wastewater treatments in electronic industries.
基金supported by the National Natural Science Foundation of China(No.51678336)the KWEF-AIT Research Grant,the President Fund for Science and Education Fusion of UCAS(No.Y552022Y00)the special fund of SKLECE,Chinese Academy of Sciences(No.KF2016-19)
文摘To understand the adsorption behavior of endocrine disrupting chemicals（EDCs） is important for enhancing the treatment performance and preventing potential secondary pollution caused by EDCs desorption in a microfiltration system. The dynamic adsorption of four representative EDCs, namely estriol（E3）, 17β-estradiol（E2）, 17α-ethynylestradiol（EE2）, and 4-nonylphenol（4-NP） in a microfiltration system was investigated using the Thomas＇ model.The product of the equilibrium constant and the total adsorption capacity of the membrane,Ka, for E3, E2, EE2, and 4-NP were 4.91, 9.78, 15.6, and 826, respectively, strongly correlating with the compound octanol–water partition coefficient（KOW）. Adsorption appeared to be enhanced when organic fouling formed on the surface of membrane, indicating the role of an additional adsorption column for EDCs acted by a fouling layer in microfiltration. Results of a comparison between the Ka values for clean membrane and fouled membrane illustrated that the significant contribution made by fouling layers may be attributed to the foulant layer＇s hydrophobicity（in the case of calcium humate layer） and thickness（in the case of calcium alginate layer）. This study provided a novel perspective to quantitatively analyze the dynamic adsorption behavior of trace pollutants in membrane process.
基金supported by the National Natural Science Foundation of China (Grant Nos. 20276008 and 20776024)Visiting Scholar Foundation of State Key Laboratory of Fine Chemicals in Dalian University of Tech-nology+1 种基金the Scientific Research Project for Higher Education Institutes of Education Department of Liaoning Province (Grant No. 2009A098)Young Teacher Foundation of Dalian Maritime University (Grant No. DLMU-ZL-200817)
文摘This paper presents a method that is capable of predicting pore structure of coal-based microfiltration carbon membranes. The tubular carbon membranes are prepared from coal samples with different particle size and distribution by using the extrusion method. According to the relationship between properties of coal samples (particle size and distribution) and pore structure parameters of coal-based carbon membranes, the experiential equations of average pore size and porosity are concluded, and the change law of pore size distribution curve is also summarized. The results show pore structure properties of coal-based carbon membranes can be exactly predicted for different separation requirements by adjusting coal particle size and distribution, which allows us to minimize cost and time consuming experiments in the development of coal-based microfiltration membranes.
文摘Forward osmotic membrane bioreactor is an emerging technology that combines the advantages of forward osmosis and conventional membrane bioreactor. In this paper, bisphenol A removal by using a forward osmotic membrane bioreactor and a conventional mem- brane bioreactor that shared one biologic reactor was studied. The total removal rate of bisphenol A by the conventional membrane bioreactor and forward osmotic membrane bioreactor was as high as 93.9% and 98%, respectively. Biodegradation plays a dominant role in the total removal of bisphenol A in both processes. In comparison of membrane rejection, the forward osmosis membrane can remove approximately 70% bisphenol A from the feed, much higher than that of the microfiltration membrane （below 10%）. Forward osmosis membrane bioreactor should be operated with its BPA loading rate under 0.08 mg. g-1. d-1 to guarantee the effluent bisphenol A concentration less thanlO μg·L-1.
文摘In the present study the membrane fouling in microfiltraiton used for cell harvesting in a deadend system has been investigated. Experimental results were analysed in terms of existing membrane filtration models and membrane resistances. The cake filtration model (CFM) and standard blocking model (SBM) have been considered in this study.Various membrane resistances were determined at different processing time, feed concentration and stirring speed. Resistances to permeation in this system include filter medium, pore blocking, adsorption, cake layer and concentration polarization.
文摘In this research,the treatability of solids from sanitary landfill leachate by microfiltration membrane was investigated and the fouling of the membrane was carefully studied.Continuous microfiltration process was carried out for 21 h in experimental system involved coagulation with Moringa oleifera followed by filtration using submerged hollow fibre microfiltration membrane (MFM).Coagulation with M.Oleifera,air diffusers and back flush technique were used for preventing or alleviating fouling of the membrane.The hollow fibre MFM showed high removals of 98%,91% and 99% for turbidity,colour and total suspended solids respectively.It was obtained at the beginning of the filtration.However,quality of the filtrate rapidly declined during the filtration process.Fouling was found to proceed according to the classical cake filtration model.Coagulation with M.Oleifera as well as the back-flush technique could not fully restore the deterioration occurred to the membrane.
