Photocatalytic membranes hold significant potential for promoting pollutant degradation and reducing membrane fouling in filtration systems.Although extensive research has been conducted on the independent design of p...Photocatalytic membranes hold significant potential for promoting pollutant degradation and reducing membrane fouling in filtration systems.Although extensive research has been conducted on the independent design of photocatalysts or membrane materials to improve their catalytic and filtration performance,the complex structures and interface mechanisms,as well as insufficient light utilization,are still often overlooked,limiting the overall performance improvement of photocatalytic membranes.This work provides an overview of enhancement strategies involving restricted area effects,external fields,such as mechanical,magnetic,thermal,and electrical fields,as well as coupling techniques with advanced oxidation processes(e.g.,O_(3),Fenton,and persulfate oxidation)for dual enhancement of photocatalysts and membranes.In addition,the synthesis method of photocatalytic membranes and the influence of factors,such as light source type,frequency,and relative position on photocatalytic membrane performance were also studied.Finally,economic feasibility and pollutant removal performance were further evaluated to determine the promising enhancement strategies,paving the way for more efficient and scalable applications of photocatalytic membranes.展开更多
The largest amount of dairy by-products, especially the whey, comes from the manufacture of cheese. The whey proteins are used in several different industry technologies. The forage production is used for animal feedi...The largest amount of dairy by-products, especially the whey, comes from the manufacture of cheese. The whey proteins are used in several different industry technologies. The forage production is used for animal feeding in the forms of various flours mixed in feeds, and the food industry uses whey proteins as human nutrition, such as different dry soups, infant formulas and supplements. The fat components of whey may inhibit the efficient processing and might impair the use of whey in these technologies. Thus, the aim of the experiment was to investigate a cheap and economical separation of the lipid fraction of whey. This separation method was made by microfiltration, which is an inexpensive, effective and energy efficient method for this task. During the measurements, 0.2 μm and 0.45 μm microfiltration membranes were used in a laboratory tubular membrane filtration module, and the membrane separation method was combined and modified by using astatic mixer and/or air insufflation. The same pore size membranes were used in a vibrating membrane filtration equipment （VSEP）, too. The two different membrane filtration devices allowed the comparison of the effect of vibration and the effect of the static mixer and/or air insufflation. The flux values above 0.2 MPa transmembrane pressures strongly decreased on using the tubular membrane. Therefore, it can be determined that the use of the lower transmembrane pressures gave better flux combined with air insufflation and the use of static mixer. The flux values increased three times higher with using vibration during the microfiltration process than that without vibration. Comparing these methods, it can be concluded that the separation made on tubular membrane （0.2 μm） combined with statics mixer gave sufficient result according to the degreasing, retentions and flux values of the other components.展开更多
Water supply and sanitation demands are foreseen to face enormous challenges over the coming decades to meet the fast growing needs in a global perspective. Significant growth in the industry is predicted and membrane...Water supply and sanitation demands are foreseen to face enormous challenges over the coming decades to meet the fast growing needs in a global perspective. Significant growth in the industry is predicted and membrane separation technologies have been identified as one of the possible solutions to meet future demands. Application and implementation of membrane technology is expected both in production of potable water as well as in treatment of wastewater. In potable water production membranes are substituting conventional separation technologies due to the superior performance, potential for less chemical use and sludge production, as well as the potential to fulfill hygienic barrier requirements. Membrane bio-reactor （MBR） technology is probably the membrane process which has had most success and has the best prospects for the future in wastewater treatment. Trends and developments indicate that this technology is becoming accepted and is rapidly becoming the best available technology for many wastewater treatment applications. A major drawback of MBR systems is membrane fouling. Studies have shown that fouling mitigation in MBR systems can potentially be done by coupling coagulation and flocculation to the process.展开更多
This ranearch is focused on the, develonment of a simnle design model of the submerged catalysis/membrane filtration （catalysis/MF） system for phenol hydroxylation over TS-1 based on the material balance of the phen...This ranearch is focused on the, develonment of a simnle design model of the submerged catalysis/membrane filtration （catalysis/MF） system for phenol hydroxylation over TS-1 based on the material balance of the phenol under steady state and the reported kinetic studies. Based on the developed model, the theoretical phenol Conversions at steady state could be calculated using the kinetic parameters obtained from the previous batch experiments. The theoretical conversions are in good agreement with the experimental data obtained in the submerged catalysis/MF system within relative error of ±5%. The model can be used to determine the optimal experimental conditions to carry out the phenol hydroxylation over TS-1 in the submerged catalysis/MF system.展开更多
Unlike the role of the membrane in a membrane bioreactor, which is designed to replace a sediment tank, direct sewage membrane filtration（DSMF）, with the goal of concentrating organic matters, is proposed as a pretr...Unlike the role of the membrane in a membrane bioreactor, which is designed to replace a sediment tank, direct sewage membrane filtration（DSMF）, with the goal of concentrating organic matters, is proposed as a pretreatment process in a novel sewage treatment concept. The concept of membrane-based pretreatment is proposed to divide raw sewage into a concentrated part retaining most organics and a filtered part with less pollutant remaining, so that energy recovery and water reuse, respectively, could be realized by post-treatment. A pilot-scale experiment was carried out to verify the feasibility of coagulant/adsorbent addition for membrane fouling control, which has been the main issue during this DSMF process. The results showed that continuous coagulant addition successfully slowed down the increase in filtration resistance, with the resistance maintained below 1.0 × 1013m^（-1） in the first 70 hr before a jump occurred. Furthermore,the adsorbent addition contributed to retarding the occurrence of the filtration resistance jump, achieving simultaneous fouling control and chemical oxygen demand（COD）concentration improvement. The final concentrated COD amounted to 7500 mg/L after 6 days of operation.展开更多
This study evaluated three different dehydrated media for simultaneous detection and enumeration of total coliform （TC） and Escherichia coil in drinking water samples with a standard membrane filtration procedure. T...This study evaluated three different dehydrated media for simultaneous detection and enumeration of total coliform （TC） and Escherichia coil in drinking water samples with a standard membrane filtration procedure. The experiment indicated that the differential coliform agar （DCA） medium was the most effective among the tested media in enumerating TC and E. coil, without the need for extensive accompanying confirmation tests. The results for DCA medium were highly reproducible for both TC and E. coil with standard deviation of 6.0 and 6.1, respectively. A high agreement （82%） was found between DCA and m-Endo media on 152 drinking water samples in terms of TC positive. The DCA medium also reduced concealment of background bacteria.展开更多
Removal and recovery of phosphorus(P) from wastewater is of great importance to addressing the challenges of eutrophication and phosphorus shortage. The P removal and recovery performance of conventional electrochemic...Removal and recovery of phosphorus(P) from wastewater is of great importance to addressing the challenges of eutrophication and phosphorus shortage. The P removal and recovery performance of conventional electrochemical precipitation approach was constrained by the limited mass transfer rate. Herein,a cathodic membrane filtration(CMF) reactor was developed using Ti/SnO_(2)-Sb anode and titanium mesh cathodic membrane module to achieve efficient removal and recovery of P in wastewater. Compared with the flow-by mode, the CMF system in the flow-through mode exhibited excellent P removal performance due to the markedly enhanced mass transfer. At the current density of 4 A/m^(2), membrane flux of 16.6 L m^(-2)h^(-1), and Ca/P molar ratio of 1.67, the removal efficiency of P was 96.2% and the energy consumption was only 45.7 k Wh/kg P. The local high p H of cathode surface played a vital role in P removal,which substantially accelerated the nucleation of calcium phosphate(Ca P). Based on the crystalline and morphological characterization of the precipitates, the hydroxyapatite was the most stable crystalline phase of Ca P, which was transformed from intermediate phases(such as dicalcium phosphate and amorphous calcium phosphate). This study paves the way for applying electrochemical membrane filtration system for P removal and recovery from wastewater.展开更多
Direct membrane filtration(DMF)is a popular option for raw sewage pre-concentration for the subsequent organic resource recovery.It undergoes rapid and severe fouling.To achieve a fundamental understanding of the cont...Direct membrane filtration(DMF)is a popular option for raw sewage pre-concentration for the subsequent organic resource recovery.It undergoes rapid and severe fouling.To achieve a fundamental understanding of the contributions of key foulants to DMF,principal component analysis(PCA)using Fourier transform infrared spectroscopy(FTIR)was applied to identify three stages of DMF.Variance partitioning analysis(VPA)and partial least squares(PLS)were used to quantitatively determine the contributions of key foulants.Humic acid(HA)achieved the highest intersection contribution(40.5%)to the total variance of the increase in resistance.Meanwhile,HA and protein(PN)explained 20.1%in the middle stage of DMF.The overall marginal effect of HA accounted for 42.5%of the variance,in conjunction with an overall individual effect of 11.0%(which was the highest in the initial stage:15.1%).The variable importance in projection(VIP)of impact on the resistance increase of DMF were 1.16(PN),0.99(HA),and 0.82(polysaccharides,PS).HA&PN with a VIP value approaching or larger than one significantly influenced the resistance increase in DMF.Meanwhile,the VIP of impact on blocking model alteration were 1.03(PS),1.01(PN),and 0.96(HA).HA,PS,and PN were regarded as vital factors in the fouling mode alteration.PS drives the fouling mode in the initial stage,whereas HA&PN and PN play dominant roles in the middle and final stages.Measures targeting HA and PN removal can be adapted for the efficient and cost-effective fouling control of raw sewage DMF.展开更多
Bioelectrochemical systems(BES)have emerged as a dual-function technology for treating wastewater and recovering energy.A vital element of BES is the rapid formation and maintenance of electroactive biofilms(EABs).Pre...Bioelectrochemical systems(BES)have emerged as a dual-function technology for treating wastewater and recovering energy.A vital element of BES is the rapid formation and maintenance of electroactive biofilms(EABs).Previous attempts to accelerate EAB formation and improve electroactivities focused on enhancing the bacterial adhesion process while neglecting the rate-limiting step of the bacterial transport process.Here,we introduce membrane filtration into BES,establishing a dynamic membrane filtration system that enhances overall performance.We observed that optimal membrane flux considerably reduced the startup time for EAB formation.Specifically,EABs established under a 25 L m^(-2)h^(-1)flux(EAB_(25)LMH)had a formation time of 43.8±1.3 h,notably faster than the 51.4±1.6 h in the static state(EAB_(0)LMH).Additionally,EAB_(25)LMH exhibited a significant increase in maximum current density,approximately 2.2 times higher than EAB_(0)LMH.Pearson correlation analysis indicated a positive relationship between current densities and biomass quantities and an inverse correlation with startup time.Microbial analysis revealed two critical findings:(i)variations in maximum current densities across different filtration conditions were associated with redox-active substances and biomass accumulation,and(ii)the incorporation of a filtration process in EAB formation enhanced the proportion of viable cells and encouraged a more diverse range of electroactive bacteria.Moreover,the novel electroactive membrane demonstrated sustained current production and effective solid-liquid separation during prolonged operation,indicating its potential as a viable alternative in membrane-based systems.This approach not only provides a new operational model for BES but also holds promise for expanding its application in future wastewater treatment solutions.展开更多
Herein,copper ion doped calcium alginate(Cu^(2+)/CaAlg)composite hydrogel filtration membranes were prepared by using natural polymer sodium alginate(NaAlg)as raw material.The thermal stability and structure of the co...Herein,copper ion doped calcium alginate(Cu^(2+)/CaAlg)composite hydrogel filtration membranes were prepared by using natural polymer sodium alginate(NaAlg)as raw material.The thermal stability and structure of the composite membranes were characterized by thermogravimetric analysis and infrared spectroscopy.The mechanical strength,anti-fouling performance,hydrophilicity and filtration performance of the membrane were studied.The results show that Cu^(2+)/CaAlg hydrogel membrane has excelle nt mechanical properties and thermal stability.The anti-swelling ability of the membrane was greatly enhanced by doping Cu^(2+).After three alternate filtration cycles,the flux recovery rate of Cu^(2+)/CaAlg hydrogel membrane can still reach 85%,indicating that the membrane has good antipollution performance.When the operation pressure was 0.1 MPa,the rejection of coomassie brilliant blue G250 reached 99.8%with a flux of 46.3 L m^(-2)h^(-1),while the Na_(2)SO_(4) rejection was less than 10.0%.The Cu^(2+)/CaAlg membrane was recycled after 24 h in the filtration process,and its flux and rejection rate did not decrease significantly,indicating that the hydrogel membrane has long-term application potential.The Cu^(2+)/CaAlg membrane has a wide range of applications prospect in dye desalination,fine separation and biopharmaceutical technology fields.展开更多
Alginate is a natural polysaccharide polymer.Hydrogel filtration membranes prepared from alginate show excellent fouling resistance and controllable separation performance,but poor mechanical properties limit the use ...Alginate is a natural polysaccharide polymer.Hydrogel filtration membranes prepared from alginate show excellent fouling resistance and controllable separation performance,but poor mechanical properties limit the use of algae hydrogels.In this study,Ba^(2+)/Ca^(2+)co-crosslinked alginate(Ba/CaAlg)hydrogel membrane was prepared by cross-linking sodium alginate with a blend aqueous solution of barium ions and calcium ions,and the membrane was applied to the separation of dyes/salts from dyeing wastewater.Compared with the CaAlg membrane,the Ba/CaAlg hydrogel membrane exhibited more stable structure,and the mechanical properties and salt tolerance of the membrane were significantly improved.The flux of Ba/CaAlg membrane for methyl blue/sodium chloride mixed solution reached 43.5 L m^(−2) h^(−1),which was significantly higher than that of CaAlg membrane.Besides,the Ba/CaAlg membrane showed higher dye rejection(>99.6%)and lower salt rejection(<8.2%).The structure of Ba/CaAlg membrane was preliminarily simulated by molecular dynamics,and the pore size and distribution of the membrane were calculated.The Ba/CaAlg membrane has a broad application prospect in dyes/salts separation.展开更多
The polyurethane/polyacrylonitrile (PU/PAN) and polyurethane/cellulose acetate (PU/CA) blend ultra filtration membranes were prepared based on Loeb-Sourirajan phase transition method. The change of the structures and ...The polyurethane/polyacrylonitrile (PU/PAN) and polyurethane/cellulose acetate (PU/CA) blend ultra filtration membranes were prepared based on Loeb-Sourirajan phase transition method. The change of the structures and properties of the PU/PAN and PU/CA membranes with the heat treatment process was studied. The results showed: the water flux decreased and retention increased with the increase of heat treatment temperature of PU/PAN blend membrane, but the water flux of PU/CA blend membrane got the maximum with heat treatment temperature of 60℃ and decreased rapidly with the heat treatment temperature of 100 ℃. The interfacial microvoid structure and its influence on the properties of PU/PAN and PU/CA blend membranes were studied.展开更多
A novel method for on-site determination of trace iron was developed using membrane preconcentration and spectrophotometric detection. Fe（II）-ferrozine complex was reacted with cetyltrimethylammonium bromide （CTAB...A novel method for on-site determination of trace iron was developed using membrane preconcentration and spectrophotometric detection. Fe（II）-ferrozine complex was reacted with cetyltrimethylammonium bromide （CTAB） to form a Fe（II）-ferrozine-CTAB paired compound, which was collected on a membrane by filtration under vacuum. The membrane was immersed in 2 mL of ethanol-nitric acid and the absorbance of the solution measured for quantitative analysis. Various factors affecting the iron collection and determination were investigated. With different sample preconcentration volumes, the range of determination was broadened to 0.5-120 ~tg/L. The detection limit of this method reached 0.19 ktg/L and the recoveries were between 97.2 and 109% when the concentration enrichment was about 45. The relative standard deviation （n = 7） was 1.9% for samples containing 10 ~g/L Fe. Twelve seawater samples were analyzed on-site using the proposed method, and two were also analyzed in inductively coupled plasma mass spectrometry. No significant difference was shown between the two methods by the Student＇s t-test. The method has also been used on-site for iron enrichment experiments with phytoplankton and concluded to be simple, accurate and inexpensive.展开更多
Membrane filtration is one of the effective approaches to harvest microalgae for industrial biofuel production.However,during the filtration process,microalgae cells and extracellular organic matter(EOM)will deposit o...Membrane filtration is one of the effective approaches to harvest microalgae for industrial biofuel production.However,during the filtration process,microalgae cells and extracellular organic matter(EOM)will deposit on the membrane surface leading to reversible membrane fouling that can be removed by physical methods.When hydrophobic EOM is adsorbed on the membrane surface or inside pores,it will build up a gel layer,causing irreversible membrane fouling.Irreversible fouling can only be removed using chemical methods that will decrease membrane lifespan and increase operational costs.Here,we introduce a versatile superhydrophilic membrane with photo-Fenton self-cleaning property,which can prevent the reversible fouling and remove the irreversible fouling.Tannic acid(TA)and 3-aminopropyltriethoxysilane(APTES)were co-deposited on the polyvinylidene fluoride(PVDF)membrane via Schiff base and Michael addition reactions,andβ-FeOOH nanorods were inlaid on the membrane surface by in situ mineralization.The water contact angle of the modified membrane is reduced from 120°to 0°Under 60 min visible light,the hydroxyl radical(·OH)generated by the photo-Fenton reaction degraded the irreversible fouling that blocked membrane pores.The irreversible fouling rates of modified membrane was reduced from 39.57%to 3.26%,compared with the original membrane.Microalgae harvesting results illustrated that the membrane has a high flux recovery rate(FRR)of 98.2%,showed excellent passive antifouling and active antifouling performance.We believe this work will spark a novel platform for optimizing energy-efficient microalgae harvesting separation membrane modules.In addition,this method of anti-fouling filtration for microorganisms can be extended to the industrial production of various bioenergy sources and will have very promising practical applications.展开更多
Aluminum salt coagulants were used prevalently in various water works. In this article, the effects of filtration on residual aluminum concentration and species distribution were researched by determining the concentr...Aluminum salt coagulants were used prevalently in various water works. In this article, the effects of filtration on residual aluminum concentration and species distribution were researched by determining the concentration of different aluminum species before and after single layer filter, double layer filter, and membrane filtration units. In the research, size exclusion chromatography （SEC） was used to separate colloidal and soluble aluminum, ion exchange chromatography （IEC） was used to separate organic and inorganic aluminum, and inductivity coupled plasma-atomic emission spectrometry （ICP-AES） was used to determine the aluminum concentration. The results showed that the rapid filtration process had the ability of removing residual aluminum from coagulant effluent water, and that double layer filtration was more effective in residual aluminum removal than single layer filtration, while nano filtration was more effective than micro filtration. It was found that when the residual aluminum concentration was below lmg/L in sediment effluent, the residual aluminum concentration in treated water was above 0.2 mg/L. The direct rapid filtration process mainly removed the suspended aluminum. The removal of soluble and colloidal aluminum was always less than 10% and the natural small particles that adsorbed the amount of soluble or small particles aluminum on their surface were difficult to be removed in this process. Micro filtration and nano filtration were good technologies for removing aluminum; the residual aluminum concentration in the effluent was less than 0.05 mg/L.展开更多
Dye desalination is a challenge in the treatment of textile wastewater with high salt concentration. It is imperative to develop salt resistance membrane that is from sustainable materials to effectively treat dye/sal...Dye desalination is a challenge in the treatment of textile wastewater with high salt concentration. It is imperative to develop salt resistance membrane that is from sustainable materials to effectively treat dye/salt mixtures. And most polymer membrane materials are non-renewable petrochemical resources.In this paper, a green hydrogel membrane(CMCS-OA-Na Alg) was prepared by non-metallic ions of oxalic acid(OA) cross-linking of two natural macromolecules of sodium alginate(Na Alg) and carboxymethyl chitosan(CMCS). The membrane showed excellent anti-swelling at high salt concentration(swelling rate less than 8.0% in 10.0 wt% Na Cl solution) and good anti-fouling performance. The membrane exhibited a rejection higher than 95.0% for dyes(bright blue, direct black, direct red, and Congo red) and lower than7.0% for Na Cl, which can achieve better dye/Na Cl separation performance. This study provides a promising membrane material for high salt textile wastewater treatment only using water and carbohydrates as raw materials without any organic solvents.展开更多
Cyanobacterial bloom has many adverse effects on source water quality and drinking water production. The traditional water treatment process can hardly achieve satisfactory removal of algae cells. This review examines...Cyanobacterial bloom has many adverse effects on source water quality and drinking water production. The traditional water treatment process can hardly achieve satisfactory removal of algae cells. This review examines the impact of pre-oxidation on the removal of cyanobacteria by solid-liquid separation processes. It was reported that the introduction of chemical oxidants such as chlorine, potassium permanganate, and ozone in algae-laden water pretreatment could improve algae removal by the subsequent solid-liquid separation processes. However, over dosed oxidants can result in more serious water quality risks due to significant algae cell lysis and undesirable intracellular organic matter release. It was suggested that moderate pre-oxidation may enhance the removal of cyanobacteria without damaging algae cells. In this article, effects of moderate pretreatment on the solid-liquid separation processes(sedimentation, dissolved air flotation, and membrane filtration) are reviewed.展开更多
The catalytic hydrogenation of p-nitrophenol to p-aminophenol was investigated over Ni/Al2O3 catalyst on alumina support with different particle size. It is found that support particle size has significant influences ...The catalytic hydrogenation of p-nitrophenol to p-aminophenol was investigated over Ni/Al2O3 catalyst on alumina support with different particle size. It is found that support particle size has significant influences on physiochemical properties and catalytic activity of the resulting Ni/Al2O3 catalyst, but little influence on the selec-tivity. At a comparable amount of Ni loading, the catalytic activity of Ni/Al2O3 prepared with alumina support of smaller particle size is lower. The reduction behavior of the catalyst is a key factor in determining the catalytic activity of Ni/Al2O3 catalyst. The supported nickel catalyst 10.3Ni/Al2O3-3 improves the life span of the membrane by reducing fouling on the membrane surface compared to nano-sized nickel.展开更多
The process of using flat-sheet membrane for simultaneous sludge thickening and digestion （MSTD） was employed. The variations of sludge concentration and rheology were characterized and simulated. Based on mass bala...The process of using flat-sheet membrane for simultaneous sludge thickening and digestion （MSTD） was employed. The variations of sludge concentration and rheology were characterized and simulated. Based on mass balance analysis, mathematical models were developed and successfully used to predict and evaluate the variations of sludge concentration and the digestion efficiency in the MSTD process. The apparent viscosity of sludge could be modeled as functions of mixed liquor suspended solids and shear rates. The sludge in the MSTD process showed both shear-thinning and viscoplastic behaviour, and under various shear rates different rheological models could be chosen to predict their flow behaviour. It was also found that sludge concentration and viscosity had significant correlations with membrane fouling in the MSTD process.展开更多
A new type of membrane bioreactor named 'airliftmembrane-bioreactor' is discussed. For municipal wastewaterreclamation, the preliminary study on airlift membrane-bioreactorshows its good performance such as hi...A new type of membrane bioreactor named 'airliftmembrane-bioreactor' is discussed. For municipal wastewaterreclamation, the preliminary study on airlift membrane-bioreactorshows its good performance such as higher flux and lower energyconsumption. The airlift membrane-bioreactor is potentiallyapplicable in bioengineer- ing and environmental protection fields.展开更多
基金supported by the BRICS STI Framework Programme(No.52261145703)the Higher Education Discipline Innovation Project(National 111 Project,No.B16016)the Guangxi Key Research and Development Plan Project(AB24010117).
文摘Photocatalytic membranes hold significant potential for promoting pollutant degradation and reducing membrane fouling in filtration systems.Although extensive research has been conducted on the independent design of photocatalysts or membrane materials to improve their catalytic and filtration performance,the complex structures and interface mechanisms,as well as insufficient light utilization,are still often overlooked,limiting the overall performance improvement of photocatalytic membranes.This work provides an overview of enhancement strategies involving restricted area effects,external fields,such as mechanical,magnetic,thermal,and electrical fields,as well as coupling techniques with advanced oxidation processes(e.g.,O_(3),Fenton,and persulfate oxidation)for dual enhancement of photocatalysts and membranes.In addition,the synthesis method of photocatalytic membranes and the influence of factors,such as light source type,frequency,and relative position on photocatalytic membrane performance were also studied.Finally,economic feasibility and pollutant removal performance were further evaluated to determine the promising enhancement strategies,paving the way for more efficient and scalable applications of photocatalytic membranes.
文摘The largest amount of dairy by-products, especially the whey, comes from the manufacture of cheese. The whey proteins are used in several different industry technologies. The forage production is used for animal feeding in the forms of various flours mixed in feeds, and the food industry uses whey proteins as human nutrition, such as different dry soups, infant formulas and supplements. The fat components of whey may inhibit the efficient processing and might impair the use of whey in these technologies. Thus, the aim of the experiment was to investigate a cheap and economical separation of the lipid fraction of whey. This separation method was made by microfiltration, which is an inexpensive, effective and energy efficient method for this task. During the measurements, 0.2 μm and 0.45 μm microfiltration membranes were used in a laboratory tubular membrane filtration module, and the membrane separation method was combined and modified by using astatic mixer and/or air insufflation. The same pore size membranes were used in a vibrating membrane filtration equipment （VSEP）, too. The two different membrane filtration devices allowed the comparison of the effect of vibration and the effect of the static mixer and/or air insufflation. The flux values above 0.2 MPa transmembrane pressures strongly decreased on using the tubular membrane. Therefore, it can be determined that the use of the lower transmembrane pressures gave better flux combined with air insufflation and the use of static mixer. The flux values increased three times higher with using vibration during the microfiltration process than that without vibration. Comparing these methods, it can be concluded that the separation made on tubular membrane （0.2 μm） combined with statics mixer gave sufficient result according to the degreasing, retentions and flux values of the other components.
文摘Water supply and sanitation demands are foreseen to face enormous challenges over the coming decades to meet the fast growing needs in a global perspective. Significant growth in the industry is predicted and membrane separation technologies have been identified as one of the possible solutions to meet future demands. Application and implementation of membrane technology is expected both in production of potable water as well as in treatment of wastewater. In potable water production membranes are substituting conventional separation technologies due to the superior performance, potential for less chemical use and sludge production, as well as the potential to fulfill hygienic barrier requirements. Membrane bio-reactor （MBR） technology is probably the membrane process which has had most success and has the best prospects for the future in wastewater treatment. Trends and developments indicate that this technology is becoming accepted and is rapidly becoming the best available technology for many wastewater treatment applications. A major drawback of MBR systems is membrane fouling. Studies have shown that fouling mitigation in MBR systems can potentially be done by coupling coagulation and flocculation to the process.
基金Supported by the National-Basic Research Program of China （2009CB623406）, the National High Technology Research and Development Program of China （2007AA06A402） and the National Natural Science Foundation of China （20636020）.
文摘This ranearch is focused on the, develonment of a simnle design model of the submerged catalysis/membrane filtration （catalysis/MF） system for phenol hydroxylation over TS-1 based on the material balance of the phenol under steady state and the reported kinetic studies. Based on the developed model, the theoretical phenol Conversions at steady state could be calculated using the kinetic parameters obtained from the previous batch experiments. The theoretical conversions are in good agreement with the experimental data obtained in the submerged catalysis/MF system within relative error of ±5%. The model can be used to determine the optimal experimental conditions to carry out the phenol hydroxylation over TS-1 in the submerged catalysis/MF system.
基金supported by the Major Science and Technology Program for Water Pollution Control and Treatment of China (No. 2012ZX07205-002)the Tsinghua University Initiative Scientific Research Program (No. 20121087922)the Program for Changjiang Scholars and Innovative Research Team in University (No. IRT1152)
文摘Unlike the role of the membrane in a membrane bioreactor, which is designed to replace a sediment tank, direct sewage membrane filtration（DSMF）, with the goal of concentrating organic matters, is proposed as a pretreatment process in a novel sewage treatment concept. The concept of membrane-based pretreatment is proposed to divide raw sewage into a concentrated part retaining most organics and a filtered part with less pollutant remaining, so that energy recovery and water reuse, respectively, could be realized by post-treatment. A pilot-scale experiment was carried out to verify the feasibility of coagulant/adsorbent addition for membrane fouling control, which has been the main issue during this DSMF process. The results showed that continuous coagulant addition successfully slowed down the increase in filtration resistance, with the resistance maintained below 1.0 × 1013m^（-1） in the first 70 hr before a jump occurred. Furthermore,the adsorbent addition contributed to retarding the occurrence of the filtration resistance jump, achieving simultaneous fouling control and chemical oxygen demand（COD）concentration improvement. The final concentrated COD amounted to 7500 mg/L after 6 days of operation.
文摘This study evaluated three different dehydrated media for simultaneous detection and enumeration of total coliform （TC） and Escherichia coil in drinking water samples with a standard membrane filtration procedure. The experiment indicated that the differential coliform agar （DCA） medium was the most effective among the tested media in enumerating TC and E. coil, without the need for extensive accompanying confirmation tests. The results for DCA medium were highly reproducible for both TC and E. coil with standard deviation of 6.0 and 6.1, respectively. A high agreement （82%） was found between DCA and m-Endo media on 152 drinking water samples in terms of TC positive. The DCA medium also reduced concealment of background bacteria.
基金National Natural Science Foundation of China (Nos. 51925806&51838009)the Shanghai Sailing Program(No. 22YF1450700)for the financial support。
文摘Removal and recovery of phosphorus(P) from wastewater is of great importance to addressing the challenges of eutrophication and phosphorus shortage. The P removal and recovery performance of conventional electrochemical precipitation approach was constrained by the limited mass transfer rate. Herein,a cathodic membrane filtration(CMF) reactor was developed using Ti/SnO_(2)-Sb anode and titanium mesh cathodic membrane module to achieve efficient removal and recovery of P in wastewater. Compared with the flow-by mode, the CMF system in the flow-through mode exhibited excellent P removal performance due to the markedly enhanced mass transfer. At the current density of 4 A/m^(2), membrane flux of 16.6 L m^(-2)h^(-1), and Ca/P molar ratio of 1.67, the removal efficiency of P was 96.2% and the energy consumption was only 45.7 k Wh/kg P. The local high p H of cathode surface played a vital role in P removal,which substantially accelerated the nucleation of calcium phosphate(Ca P). Based on the crystalline and morphological characterization of the precipitates, the hydroxyapatite was the most stable crystalline phase of Ca P, which was transformed from intermediate phases(such as dicalcium phosphate and amorphous calcium phosphate). This study paves the way for applying electrochemical membrane filtration system for P removal and recovery from wastewater.
基金supported by the National Natural Science Foundation of China(No.51608298)the Open Research Fund Program of Cultivation Project of Double First-Class Disciplines of Environmental Science and Engineering,Beijing Technology&Business University(BTBU,ESE2022YB07)the Graduate Research and Practice Projects of Minzu University of China.We would like to thank Editage for English language editing。
文摘Direct membrane filtration(DMF)is a popular option for raw sewage pre-concentration for the subsequent organic resource recovery.It undergoes rapid and severe fouling.To achieve a fundamental understanding of the contributions of key foulants to DMF,principal component analysis(PCA)using Fourier transform infrared spectroscopy(FTIR)was applied to identify three stages of DMF.Variance partitioning analysis(VPA)and partial least squares(PLS)were used to quantitatively determine the contributions of key foulants.Humic acid(HA)achieved the highest intersection contribution(40.5%)to the total variance of the increase in resistance.Meanwhile,HA and protein(PN)explained 20.1%in the middle stage of DMF.The overall marginal effect of HA accounted for 42.5%of the variance,in conjunction with an overall individual effect of 11.0%(which was the highest in the initial stage:15.1%).The variable importance in projection(VIP)of impact on the resistance increase of DMF were 1.16(PN),0.99(HA),and 0.82(polysaccharides,PS).HA&PN with a VIP value approaching or larger than one significantly influenced the resistance increase in DMF.Meanwhile,the VIP of impact on blocking model alteration were 1.03(PS),1.01(PN),and 0.96(HA).HA,PS,and PN were regarded as vital factors in the fouling mode alteration.PS drives the fouling mode in the initial stage,whereas HA&PN and PN play dominant roles in the middle and final stages.Measures targeting HA and PN removal can be adapted for the efficient and cost-effective fouling control of raw sewage DMF.
基金financially supported by the National Natural Science Foundation of China(52200059 and 22036004)“the Fundamental Research Funds for the Central Universities,”Nankai University(Grant 63231127).
文摘Bioelectrochemical systems(BES)have emerged as a dual-function technology for treating wastewater and recovering energy.A vital element of BES is the rapid formation and maintenance of electroactive biofilms(EABs).Previous attempts to accelerate EAB formation and improve electroactivities focused on enhancing the bacterial adhesion process while neglecting the rate-limiting step of the bacterial transport process.Here,we introduce membrane filtration into BES,establishing a dynamic membrane filtration system that enhances overall performance.We observed that optimal membrane flux considerably reduced the startup time for EAB formation.Specifically,EABs established under a 25 L m^(-2)h^(-1)flux(EAB_(25)LMH)had a formation time of 43.8±1.3 h,notably faster than the 51.4±1.6 h in the static state(EAB_(0)LMH).Additionally,EAB_(25)LMH exhibited a significant increase in maximum current density,approximately 2.2 times higher than EAB_(0)LMH.Pearson correlation analysis indicated a positive relationship between current densities and biomass quantities and an inverse correlation with startup time.Microbial analysis revealed two critical findings:(i)variations in maximum current densities across different filtration conditions were associated with redox-active substances and biomass accumulation,and(ii)the incorporation of a filtration process in EAB formation enhanced the proportion of viable cells and encouraged a more diverse range of electroactive bacteria.Moreover,the novel electroactive membrane demonstrated sustained current production and effective solid-liquid separation during prolonged operation,indicating its potential as a viable alternative in membrane-based systems.This approach not only provides a new operational model for BES but also holds promise for expanding its application in future wastewater treatment solutions.
基金supported by National Natural Science Foundation of China(Nos.51678409,51708406,51708407)Tianjin Science Technology Research Funds of China(Nos.16JCZDJC37500,15JCZDJC38300)Tianjin Science and Technology Plan Project(No.18ZXJMTG00120)。
文摘Herein,copper ion doped calcium alginate(Cu^(2+)/CaAlg)composite hydrogel filtration membranes were prepared by using natural polymer sodium alginate(NaAlg)as raw material.The thermal stability and structure of the composite membranes were characterized by thermogravimetric analysis and infrared spectroscopy.The mechanical strength,anti-fouling performance,hydrophilicity and filtration performance of the membrane were studied.The results show that Cu^(2+)/CaAlg hydrogel membrane has excelle nt mechanical properties and thermal stability.The anti-swelling ability of the membrane was greatly enhanced by doping Cu^(2+).After three alternate filtration cycles,the flux recovery rate of Cu^(2+)/CaAlg hydrogel membrane can still reach 85%,indicating that the membrane has good antipollution performance.When the operation pressure was 0.1 MPa,the rejection of coomassie brilliant blue G250 reached 99.8%with a flux of 46.3 L m^(-2)h^(-1),while the Na_(2)SO_(4) rejection was less than 10.0%.The Cu^(2+)/CaAlg membrane was recycled after 24 h in the filtration process,and its flux and rejection rate did not decrease significantly,indicating that the hydrogel membrane has long-term application potential.The Cu^(2+)/CaAlg membrane has a wide range of applications prospect in dye desalination,fine separation and biopharmaceutical technology fields.
基金supported by the National Natural Science Foundation of China(No.22078244)Scientific research and development project of SINOPEC(No.222443)the Science and Technology Plans of Tianjin(No.20JCYBJC00120).
文摘Alginate is a natural polysaccharide polymer.Hydrogel filtration membranes prepared from alginate show excellent fouling resistance and controllable separation performance,but poor mechanical properties limit the use of algae hydrogels.In this study,Ba^(2+)/Ca^(2+)co-crosslinked alginate(Ba/CaAlg)hydrogel membrane was prepared by cross-linking sodium alginate with a blend aqueous solution of barium ions and calcium ions,and the membrane was applied to the separation of dyes/salts from dyeing wastewater.Compared with the CaAlg membrane,the Ba/CaAlg hydrogel membrane exhibited more stable structure,and the mechanical properties and salt tolerance of the membrane were significantly improved.The flux of Ba/CaAlg membrane for methyl blue/sodium chloride mixed solution reached 43.5 L m^(−2) h^(−1),which was significantly higher than that of CaAlg membrane.Besides,the Ba/CaAlg membrane showed higher dye rejection(>99.6%)and lower salt rejection(<8.2%).The structure of Ba/CaAlg membrane was preliminarily simulated by molecular dynamics,and the pore size and distribution of the membrane were calculated.The Ba/CaAlg membrane has a broad application prospect in dyes/salts separation.
文摘The polyurethane/polyacrylonitrile (PU/PAN) and polyurethane/cellulose acetate (PU/CA) blend ultra filtration membranes were prepared based on Loeb-Sourirajan phase transition method. The change of the structures and properties of the PU/PAN and PU/CA membranes with the heat treatment process was studied. The results showed: the water flux decreased and retention increased with the increase of heat treatment temperature of PU/PAN blend membrane, but the water flux of PU/CA blend membrane got the maximum with heat treatment temperature of 60℃ and decreased rapidly with the heat treatment temperature of 100 ℃. The interfacial microvoid structure and its influence on the properties of PU/PAN and PU/CA blend membranes were studied.
基金Supported by State Key Laboratory of Marine Environmental Science(MEL)Funds(No.MELRI1001)
文摘A novel method for on-site determination of trace iron was developed using membrane preconcentration and spectrophotometric detection. Fe（II）-ferrozine complex was reacted with cetyltrimethylammonium bromide （CTAB） to form a Fe（II）-ferrozine-CTAB paired compound, which was collected on a membrane by filtration under vacuum. The membrane was immersed in 2 mL of ethanol-nitric acid and the absorbance of the solution measured for quantitative analysis. Various factors affecting the iron collection and determination were investigated. With different sample preconcentration volumes, the range of determination was broadened to 0.5-120 ~tg/L. The detection limit of this method reached 0.19 ktg/L and the recoveries were between 97.2 and 109% when the concentration enrichment was about 45. The relative standard deviation （n = 7） was 1.9% for samples containing 10 ~g/L Fe. Twelve seawater samples were analyzed on-site using the proposed method, and two were also analyzed in inductively coupled plasma mass spectrometry. No significant difference was shown between the two methods by the Student＇s t-test. The method has also been used on-site for iron enrichment experiments with phytoplankton and concluded to be simple, accurate and inexpensive.
基金supported by the Fujian Provincial Science and Technology Cooperation Project(No.20210002)National Natural Science Foundation of China(No.31870994).
文摘Membrane filtration is one of the effective approaches to harvest microalgae for industrial biofuel production.However,during the filtration process,microalgae cells and extracellular organic matter(EOM)will deposit on the membrane surface leading to reversible membrane fouling that can be removed by physical methods.When hydrophobic EOM is adsorbed on the membrane surface or inside pores,it will build up a gel layer,causing irreversible membrane fouling.Irreversible fouling can only be removed using chemical methods that will decrease membrane lifespan and increase operational costs.Here,we introduce a versatile superhydrophilic membrane with photo-Fenton self-cleaning property,which can prevent the reversible fouling and remove the irreversible fouling.Tannic acid(TA)and 3-aminopropyltriethoxysilane(APTES)were co-deposited on the polyvinylidene fluoride(PVDF)membrane via Schiff base and Michael addition reactions,andβ-FeOOH nanorods were inlaid on the membrane surface by in situ mineralization.The water contact angle of the modified membrane is reduced from 120°to 0°Under 60 min visible light,the hydroxyl radical(·OH)generated by the photo-Fenton reaction degraded the irreversible fouling that blocked membrane pores.The irreversible fouling rates of modified membrane was reduced from 39.57%to 3.26%,compared with the original membrane.Microalgae harvesting results illustrated that the membrane has a high flux recovery rate(FRR)of 98.2%,showed excellent passive antifouling and active antifouling performance.We believe this work will spark a novel platform for optimizing energy-efficient microalgae harvesting separation membrane modules.In addition,this method of anti-fouling filtration for microorganisms can be extended to the industrial production of various bioenergy sources and will have very promising practical applications.
基金Project supported by the National Natural Science Foundation of China(No. 50238020)the American Aluminum Foundation.
文摘Aluminum salt coagulants were used prevalently in various water works. In this article, the effects of filtration on residual aluminum concentration and species distribution were researched by determining the concentration of different aluminum species before and after single layer filter, double layer filter, and membrane filtration units. In the research, size exclusion chromatography （SEC） was used to separate colloidal and soluble aluminum, ion exchange chromatography （IEC） was used to separate organic and inorganic aluminum, and inductivity coupled plasma-atomic emission spectrometry （ICP-AES） was used to determine the aluminum concentration. The results showed that the rapid filtration process had the ability of removing residual aluminum from coagulant effluent water, and that double layer filtration was more effective in residual aluminum removal than single layer filtration, while nano filtration was more effective than micro filtration. It was found that when the residual aluminum concentration was below lmg/L in sediment effluent, the residual aluminum concentration in treated water was above 0.2 mg/L. The direct rapid filtration process mainly removed the suspended aluminum. The removal of soluble and colloidal aluminum was always less than 10% and the natural small particles that adsorbed the amount of soluble or small particles aluminum on their surface were difficult to be removed in this process. Micro filtration and nano filtration were good technologies for removing aluminum; the residual aluminum concentration in the effluent was less than 0.05 mg/L.
基金supported by the National Natural Science Foundation of China (Nos. 51708407 and 51803150)the Science and Technology Plans of Tianjin (Nos. 19JCQNJC02900, 18ZXJMTG00120,20JCYBJC00120)。
文摘Dye desalination is a challenge in the treatment of textile wastewater with high salt concentration. It is imperative to develop salt resistance membrane that is from sustainable materials to effectively treat dye/salt mixtures. And most polymer membrane materials are non-renewable petrochemical resources.In this paper, a green hydrogel membrane(CMCS-OA-Na Alg) was prepared by non-metallic ions of oxalic acid(OA) cross-linking of two natural macromolecules of sodium alginate(Na Alg) and carboxymethyl chitosan(CMCS). The membrane showed excellent anti-swelling at high salt concentration(swelling rate less than 8.0% in 10.0 wt% Na Cl solution) and good anti-fouling performance. The membrane exhibited a rejection higher than 95.0% for dyes(bright blue, direct black, direct red, and Congo red) and lower than7.0% for Na Cl, which can achieve better dye/Na Cl separation performance. This study provides a promising membrane material for high salt textile wastewater treatment only using water and carbohydrates as raw materials without any organic solvents.
基金supported by the National Key Research and Development Project (No. 2018YFE0204101)National Natural Science Foundation of China (No. 51808531)。
文摘Cyanobacterial bloom has many adverse effects on source water quality and drinking water production. The traditional water treatment process can hardly achieve satisfactory removal of algae cells. This review examines the impact of pre-oxidation on the removal of cyanobacteria by solid-liquid separation processes. It was reported that the introduction of chemical oxidants such as chlorine, potassium permanganate, and ozone in algae-laden water pretreatment could improve algae removal by the subsequent solid-liquid separation processes. However, over dosed oxidants can result in more serious water quality risks due to significant algae cell lysis and undesirable intracellular organic matter release. It was suggested that moderate pre-oxidation may enhance the removal of cyanobacteria without damaging algae cells. In this article, effects of moderate pretreatment on the solid-liquid separation processes(sedimentation, dissolved air flotation, and membrane filtration) are reviewed.
基金Supported by the Special Funds for Major State Basic Research Program of China （No.2003CB615702）, the National Natural Science Foundation of China （No.20636020） and the Natural Science Foundation of Jiangsu Province （No.BK2006722）.
文摘The catalytic hydrogenation of p-nitrophenol to p-aminophenol was investigated over Ni/Al2O3 catalyst on alumina support with different particle size. It is found that support particle size has significant influences on physiochemical properties and catalytic activity of the resulting Ni/Al2O3 catalyst, but little influence on the selec-tivity. At a comparable amount of Ni loading, the catalytic activity of Ni/Al2O3 prepared with alumina support of smaller particle size is lower. The reduction behavior of the catalyst is a key factor in determining the catalytic activity of Ni/Al2O3 catalyst. The supported nickel catalyst 10.3Ni/Al2O3-3 improves the life span of the membrane by reducing fouling on the membrane surface compared to nano-sized nickel.
基金supported by the Foundation of Chinese State Key Laboratory of Pollution Control and Resource Reuse for Young Scholars (No. PCRRY08005)by the Science and Technology Commission of Shanghai Municipality (No. 08231200200)
文摘The process of using flat-sheet membrane for simultaneous sludge thickening and digestion （MSTD） was employed. The variations of sludge concentration and rheology were characterized and simulated. Based on mass balance analysis, mathematical models were developed and successfully used to predict and evaluate the variations of sludge concentration and the digestion efficiency in the MSTD process. The apparent viscosity of sludge could be modeled as functions of mixed liquor suspended solids and shear rates. The sludge in the MSTD process showed both shear-thinning and viscoplastic behaviour, and under various shear rates different rheological models could be chosen to predict their flow behaviour. It was also found that sludge concentration and viscosity had significant correlations with membrane fouling in the MSTD process.
文摘A new type of membrane bioreactor named 'airliftmembrane-bioreactor' is discussed. For municipal wastewaterreclamation, the preliminary study on airlift membrane-bioreactorshows its good performance such as higher flux and lower energyconsumption. The airlift membrane-bioreactor is potentiallyapplicable in bioengineer- ing and environmental protection fields.
