Ceramic Membranes

As the performance of ceramic membrane relies very much on its
structure, thus this study focus on the investigation effect of
thermodynamic properties by changing its fabrication parameters, i.e.
composition and temperature on the membrane’s surface
morphologies. Phase inversion method which commonly used for
polymeric membrane, has been employed in this work with some
modification to prepare kaolin flat sheet ceramic membrane. Kaolin
with 25µm average particle size was used as the main constituent for
membrane preparation, besides polyethersulfone as polymer binder
and N-methylpyrolidone as organic solvent. The composition of
kaolin in dope suspension were varied from 60g to 80g while the
phase inversion process was carried out at two temperatures, i.e. room
temperature (28oC) and low temperature (3oC). In this study, the
surface structure of ceramic membrane was characterized in term of
surface roughness and morphology. Result of atomic force
microscopy (AFM) showed that by decreasing phase inversion
temperature, the surface roughness decreased from 0.136µm to
0.093µm for membrane prepared at kaolin composition of 80g.
Similar trend was observed for the composition, which the roughness
decreased by the reduction of kaolin content. In addition, the SEM
images explained that membrane surface morphology obviously
changes with the effect of phase inversion temperature. Membrane
prepared at low temperature (3oC) possessed the smallest pore size of
0.043µm at kaolin composition of 80g. These experimental
observations were not predicted by any current theories of membrane
preparation and surface characterization of previous ceramic
membrane fabricated through phase inversion system, but appear to
mimic the effect of thermodynamic properties that applied in previous
study (Harun et al. 2014). In addition, this method also have been
reported to improve the problem of unsolidified ceramic membrane.
We therefore propose that the modification in this study controlled the
desired membrane surface roughness, hence called the method as
‘modified phase inversion’.

the microporous material is deposited as a thin layer on the Aqueous sodium silicate solutions and hydrochloric acid were top of a porous support which consists generally of a similar used to prepare silica gels without any additives. In order to estabmaterial with a coarser pore structure.

Membrane bioreactor (MBR) is a reliable and promising technology for wastewater treatment and reclamation applications. In spite of more than a decade of significant advances in developing fouling mitigation methods, different physical and cleaning protocols are still necessary to be developed to limit the membrane fouling. The use of scouring agents in MBR applications has been paid attention as a new approach as an energy-efficient way to control membrane fouling. Recently, mechanical cleaning by scouring agents is becoming as intense research area considering high efficiency of fouling reduction while requiring low energy consumption. In this review, fundamental and comprehensive assessments of the mechanical cleaning concepts and their applications with porous and nonporous scouring agents for MBR system are critically reviewed. The existing challenges and future research prospects on the mechanical cleaning technology associated with scouring agents for the MBR applications are also discussed.

Heterogeneous photocatalysis is a promising technology especially for environmental remediation. Despite more than a decade of worldwide research in developing photocatalytic efficiency improving techniques, many questions regarding the large scale application of photocatalytic reactors still remain unanswered. Recently, improving the photocatalytic efficiency has gained scientific attention because it might lead to more economical and robust photocatalytic operation for environmental remediation. In this review, fundamental and comprehensive assessments of the photocatalytic concepts and their applications for environmental remediation are reviewed. The existing challenges and strategies to improve the photocatalytic efficiency are discussed. Further, recent developments and future research prospects on photocatalytic systems for environmental applications are also addressed.

The need for sustainable alternatives to oil has been of deep concern to many countries around the world, and especially the U.S. due to the rapidly rising cost of oil. As a result, many nations face significant energy security challenges stemming from their dependence on imported oil. To achieve future energy security and independence
and in the long run to prepare for the post-oil energy resources, biomass is considered as one of the most important renewable energy resources in a projected sustainable energy future. The key bottleneck for lignocellulosic-derived biofuels is the lack of technology for efficient conversion of biomass in to readily usable fuel products. Current
work provides a detailed theoretical and experimental analysis of two (air and steam only) gasification technologies which are carbon neutral that can be used to overcome this hurdle.

This work also examines the use of mixed ion-electron conductors (MIEC) membranes as a significant option to enhance the production of H2 from biomass feedstock. Currently there are technologies that produce H2 by using renewable energy sources other than biomass as feedstock but they could not provide a long term solution
because of their adverse effects on eco-system. Thin film SrCe0.7Zr0.2Eu0.1 O3-δ membranes were developed and supported using NiO-SrCe0.8 Zr0.2 O3-δ tubular structure, using Dr. Eric Wachsman’s group’s work at UF. The main advantage of this
membrane setup is that it acts as WGS reactor and also separates the H2 from the gas stream, thus avoiding the need for two stage reactor setup requiring WGS and H2 separation independently. The possibility of sequestering the isolated CO2 stream is also another attribute to such membrane reactors. The overall objective of this current work is to analyze the air gasification and steam only gasification technology in detail and to investigate the performance of proton conducting ceramic membranes at high temperatures. Current research also analyzed a
simplistic model of a concept system, which is a self-sustaining H2 fuel production system that integrates the gasification technology and the MIEC membrane technology. The proposed system enhances the H2 produced from the biomass feed stock by carrying out WGS.

In biodiesel production, downstream purification is an important step in the overall process. This article is a critical review of the most recent research findings pertaining to biodiesel refining technologies. Both conventional refining technologies and the most recent biodiesel membrane refining technology are reviewed. The results obtained through membrane purification showed some promise in term of biodiesel yield and quality. Also, membranes presented low water consumption and less wastewater discharges. Therefore, exploration and exploitation of membrane technology to purify crude biodiesel is necessary. Furthermore, the success of membrane technology in the purification of crude biodiesel could serve as a boost to both researchers and industries in an effort to achieve high purity and quality biodiesel fuel capable of replacing non-renewable fossil fuel, for wide range of applications.

The present paper describes the integration of oxygen membranes in cement plants both from an energy, exergy and economic point of view. Different configurations for oxygen enrichment of the tertiary air for combustion in the pre-calciner and full oxy-fuel combustion in both pre-calciner and kiln are examined. The economic figures of merit are compared with those from a standard cryogenic plant. Both oxygen enriched air and full oxy-fuel cases allow for an increase in clinker production, use of alternative fuels as well as on-site electricity production. In addition, the full oxy-fuel cases generate a concentrated CO 2 source that can be used for enhanced oil recovery, in combination with biomass gasification and electrolysis for synthesis gas production, or possibly sequestered. The cases with oxygen enriched air provide very promising economic figures of merit with discounted payback periods slightly higher than one year. The full oxy-fuel cases have a discounted payback period of approximately 2.3 years assuming a CO 2 selling price of 35 US$/ton. The sensitivity analysis of full oxy-fuel cases clearly shows that for the discounted payback period, the most sensitive parameters are the CO 2 price and the clinker selling price.

In this present study, the root extracts of Withania somnifera were subjected to a comparative evaluation of the membrane stabilization and thrombolytic activity on human blood sample. The thrombolytic and membrane stabilizing activities were assessed by using human erythrocyte and the results were compared with standard streptokinase (SK) and standard anti-inflammatory drug, acetyl salicylic acid (ASA), respectively. The Methanol extract showed the highest thrombolytic activity (68.14%). On the other hand hypotonic solution induced haemolysis, at a concentration of 1.0 mg/ mL, the methanol extract inhibited 71.90% haemolysis of RBCs as compared to 73.56% produced by acetyl salicylic acid (0.10 mg/mL). And in case of heat induced condition different organic soluble materials of Withania somnifera demonstrated 54.03%, 53.13% and 38.54% inhibition of hemolysis of RBCs, respectively whereas ASA inhibited 48.10%.

In biodiesel production, downstream purification is an important step in the overall process. This article is a critical review of the most recent research findings pertaining to biodiesel refining technologies. Both conventional refining technologies and the most recent biodiesel membrane refining technology are reviewed. The results obtained through membrane purification showed some promise in term of biodiesel yield and quality. Also, membranes presented low water consumption and less wastewater discharges. Therefore, exploration and exploitation of membrane technology to purify crude biodiesel is necessary. Furthermore, the success of membrane technology in the purification of crude biodiesel could serve as a boost to both researchers and industries in an effort to achieve high purity and quality biodiesel fuel capable of replacing non-renewable fossil fuel, for wide range of applications. (C) 2011 Elsevier Ltd. All rights reserved

http://www.sciencedirect.com/science/article/pii/S0306261911003242

Membrane fouling was observed using microbial suspensions obtained from a sequencing batch reactor operated for simultaneous partial nitrification and anammox. Combined  effects of particle size distributions in microbial suspensions taken from the SBR and membrane pore sizes on membrane fouling are presented. With the smallest membrane pore size tested (0.1 lm), a supernatant solution led to higher fouling rate than the mixed liquor suspension having relatively bigger particle sizes and larger quantity. However, the fouling rate with two different solutions was not different significantly as the glass-fiber filter (1.2 lm pore size) was used. For the smallest membrane pore size, best fittings based upon pore blocking models showed that cake filtration played a key role in the membrane fouling. However, intermediate pore blocking was classified as dominant fouling mechanisms for the glass-fiber
filter tested. This study showed that the surface morphology of the fouling layer deposited on membrane surface could vary depending upon the surface properties of the fresh membranes and glass-fiber filter such as surface roughness. A higher surface roughness of the membrane resulted in a higher fouling rate with rougher surface of the fouling layer formed on the membrane. This study also suggested that soluble microbial products (SMP) resulted in a higher flux decline than that observed with extracellular polymeric substances (EPS) in the supernatant solution taken from the anammox SBR.

The development of new membranes with improved separation properties, high mechanical and thermal stability using inexpensive and naturally abundant materials is of utmost importance for sustainable development and environmental applications. Ceramic materials due to their high chemical, mechanical and thermal stability in combination to their facile surface functionalization have inspired material scientists to design innovative low-cost ceramic-based membrane supports. This study focuses on the preparation and characterization of novel asymmetric ultrafiltration ceramic membrane coated with single separation layer made of TiO 2 nanoparticles, and its application to removal of alizarin dye from aqueous solutions. The membrane was prepared by a simple and one-step deposition of micrometer-thick titania layer on the internal surface of the tubular-shape porous clay-alumina membrane support from an aqueous colloidal suspension of titanium oxide (TiO 2) nanoparticles with size of 10 nm. The colloidal suspension was prepared in the presence of 0.2 wt.% of Dolapix, and 30 g of an aque-ous solution of polyvinyl alcohol at 12 wt.% and 66 mL of H 2 O. Microfiltration tubular supports of 10 mm/7 mm (outer/inner diameter) were prepared through an extrusion method followed by a sintering process using China Clay Rajmahal grade and alumina, as mineral precursors. The composition of 25% of clay and 75% of alumina was selected in this work as it showed a lower sintering temperature (T f = 1350 °C) which could ensure low cost elaboration process, an average water flux of 850 L h À1 m À2 bar À1 as well as enhanced mechanical performance (%37 MPa) and large porosity (48%) with an average pore diameter of 0.75 mm. SEM characterization showed that at the sintering temperature of 800 °C, the TiO 2 nanoparticles coated densely and homogeneously the ceramic support forming a thin layer of about 4.2 mm in thickness and leading to a clear reduction of the mean pore size (50 nm approximatively) while providing a water permeability of 117 L h À1 m À2 bar À1. The so-designed ultrafil-tration (UF) tubular ceramic membrane has proved efficient for alizarin red dye removal with a retention rate of 99% and a permeate flux of 70 L h À1 m À2 at pH 9 and a transmembrane pressure of 5 bar.

To cite this article: Ganesh C. Sahoo, Rupa Halder, Ilyes Jedidi, Abdallah Oun, Hassen Nasri, Piyali Roychoudhurry, Swachchha Majumdar, Sibdas Bandyopadhyay & Raja Ben Amar (2016): Preparation and characterization of microfiltration apatite membrane over low cost clay-alumina support for decolorization of dye solution, Desalination and Water Treatment, A B S T R A C T Apatite material obtained from natural sources of Tunisian mineral has been used for the development of membrane over clay–alumina-based microporous supports. For this purpose, supports of single-channel and 19-channel circular configurations were used. The apatite powder used for membrane preparation had average pore diameter of 4.02 μm. Coating formulation has been optimized to obtain stable suspension. Powder loading of 4 wt.% was found as optimum for obtaining a proper microfiltration membrane with 0.2 μm pore diameter. Single-channel membrane was used for characterization. The application to color removal from synthetic reactive dye solution was performed using membrane with 19-channel configuration. An average water flux of 200 and 80 l/m 2 h was obtained for 19-channel support and membrane , respectively, in laboratory scale setup. Reactive red dye removal from synthetic dyeing solution was achieved up to 99%. Resulting saturated membrane was successfully regenerated using H 2 O 2 at various concentrations and contact time. Color separation efficiency of the membrane (g/m 2) has been evaluated as an indicator of membrane regeneration. Moreover, apatite membrane-based separation of reactive red dye has been compared with adsorption using the apatite powder followed by membrane separation. Apatite membrane-based separation was found to be more efficient compared to adsorptive separation using apatite powder.

Three different graphite powders with different particles sizes were tested to synthesize tubular monochannel carbon supports for micro and ultrafiltration membranes using a new process. Carbon graphite powders and organic additives were mixed with an ethanolic solution of Resol s type phenolic resin. The extruded tubes were firstly consolidated by curing the resin at 150 1C then carbonized under nitrogen stream (1 mL min −1 ) for graphitization and pores opening.

This work describes manufacturing of low-cost tubular ceramic microfiltration membrane made from natural pozzolan. Firstly, the tubular ceramic support was prepared by extrusion technique followed by sintering at low temperature of 950°C. The extruded paste is essentially composed of pozzolan powder (< 200 μm), clay (< 68 μm), some organic additives and water. This formulation is conducted to obtain a ceramic support with uniform porous structure and high water permeability. Secondly, the membrane layer was prepared by cross-flow filtration of suspension containing the pozzolan powder (< 45 μm), polyvinyl alcohol and water, thereafter the membrane was dried and sintered at 950°C. Scanning electron microscope analysis showed that the membrane has homogenous structure and is free from any defect. In addition, the average pore size and water permeability parameters were respectively 0.36 μm and 1444.7 L/h·m 2 .bar. Manufactured membrane is expected to have challenge application in pretreatment of seawater for desalination. Membrane performance was evaluated by filtration of raw seawater in the aim of reducing its turbidity and its chemical oxygen demand. Experimental results showed a high rejection of turbidity (98.25%) as well as a good retention of chemical oxygen demand (70.77%).

In biodiesel production, downstream purification is an important step in the overall process. This article is a critical review of the most recent research findings pertaining to biodiesel refining technologies. Both conventional refining technologies and the most recent biodiesel membrane refining technology are reviewed. The results obtained through membrane purification showed some promise in term of biodiesel yield and quality. Also, membranes presented low water consumption and less wastewater discharges. Therefore, exploration and exploitation of membrane technology to purify crude biodiesel is necessary. Furthermore, the success of membrane technology in the purification of crude biodiesel could serve as a boost to both researchers and industries in an effort to achieve high purity and quality biodiesel fuel capable of replacing non-renewable fossil fuel, for wide range of applications.

In this work, the ultrafiltration of macromolecules was analysed using a response surface methodological approach. The behaviour of two different inorganic membranes was investigated. The membranes selected were a Carbosep M2 membrane (Orelis, France) with a molecular weight cut-off (MWCO) of 15 kDa and a Tami MSKT membrane (Tami Industries, France) with a MWCO of 5 kDa. The solute employed was polyethylene glycol of 35 kDa molecular weight. The influence of transmembrane pressure (0.1, 0.2, 0.3, 0.4 and 0.5 MPa), crossflow velocity (1, 2 and 3 m/s) and feed concentration (5, 10 and 15 g/L) on permeate flux and permeate flux decline was investigated. Analysis of variance was proved to be a useful tool to determine the effect of operating variables on both parameters. The method used demonstrated the presence of coupled effects between factors as well as squared effects that are relevant to the ultrafiltration process. The surface contours obtained from fitted models were used for the optimization of the operating conditions. The goal was to simultaneously maximize the average permeate flux and minimize the flux decline. The optimal operating conditions for the Carbosep M2 membrane were a transmembrane pressure of 0.38 MPa and a crossflow velocity of 3 m/s. The optimal operating conditions for the Tami MSKT membrane could not be determined by means of multiple response optimization due to the low accuracy of the regression model obtained for the cumulative permeate flux decline (SFD) response variable.

A novel reduced graphene oxide composite membrane was successfully prepared on ceramic pozzolan support by chemical grafting and spin-coating method. The graphite was firstly oxidized and exfoliated to form graphene oxide (GO) that was grafted on modified ceramic surface using 3-Glycidoxypropyltrimethoxysilane (GLYMO). Then, the GO layer was thermally treated to obtain reduced graphene oxide (rGO) membrane. The concentration effect of GLYMO grafting agent was studied in the range of 0.01 to 0.1 M in ethanol. The composite membrane was characterized using XRD, FTIR, Contact angle, SEM, EDX, and AFM Techniques. The morphology analysis showed that rGO layer is homogenously adhered on pozzolan support with 2.0 μm ± 0.1 in thickness using 0.05 M of GLYMO. The experimental results indicated that water permeability decreases from 75 to 2 L/m 2 .h.bar when GLYMO concentration is increased from 0.01 to 0.1 M. The prepared membranes were applied for filtration of bromothymol blue, methyl orange and murexide solutions under pressure of 4 bar during 2 h. The membranes showed a good efficiency in rejection of soluble dyes. For membrane prepared with 0.1 M of GLYMO (optimized membrane), experimental values of rejection achieved 94, 93 and 97% for bromothymol blue, methyl orange and murexide respectively.

An aluminum dioxide (Al2O3) ceramic membrane was used in a single-stage anaerobic fluidized ceramic membrane bioreactor (AFCMBR) for low-strength wastewater treatment. The AFCMBR was operated continuously for 395 days at 25 °C using a synthetic wastewater having a chemical oxygen demand (COD) averaging 260 mg/L. A membrane net flux as high as 14.5–17 L/m2.h was achieved with only periodic maintenance cleaning, obtained by adding 25 mg/L of sodium hypochlorite solution. No adverse effect of the maintenance cleaning on organic removal was observed. An average SCOD in the membrane permeate of 23 mg/L was achieved with a 1 h hydraulic retention time (HRT). Biosolids production averaged 0.014±0.007 gVSS/gCOD removed. The estimated electrical energy required to operate the AFCMBR system was 0.038 kWh/m3, which is only about 17% of the electrical energy that could be generated with the methane produced.

Gas sparging is used as a traditional way to control membrane fouling in submerged membrane bioreactors (MBRs) in wastewater treatment. However, the gas sparging accounts for the largest fraction in operational cost to run the MBR systems. In this study, membrane fouling was controlled by integrating scouring media with gas sparging to reduce fouling rate at relatively low operational energy. Comparative study was performed using a fluidized membrane reactor treating synthetic feed solutions between polyethylene terephthalate (PET) scouring media (SM) fluidized by gas sparging (GS), liquid recirculation (LR), and combination of them to control membrane fouling. Addition of PET scouring media reduced the gas flow rate by 67% more with 30% less in fouling rate than gas sparing only. Combined usage of gas sparging and liquid recirculation to fluidize the PET scouring media (LR + GS + SM) showed 37% lower in fouling rate than that obtained by the scouring media fluidized by liquid recirculation (LR + SM) only through the reactor. The LR + GS + SM configuration reduced energy consumption by 90% more than that required by gas sparging alone. Mechanical cleaning driven by fluidizing PET scouring media could reduce membrane fouling due to removing deposit of inorganic particles from membrane surface effectively. However, the PET scouring media was not very effective to reduce membrane fouling caused by organic colloids which are expected to contribute pore fouling significantly.

Nowadays, integrated microfiltration (MF) membrane systems treatment is becoming widely popular due to its feasibility, process reliability, commercial availability, modularity, relative insensitivity in case of wastewater of various industrial sources as well as raw water treatment and lower operating costs. The well thought out, designed and implemented use of membranes can decrease capital cost, reduce chemical usage, and require little maintenance. Due to their resistance to extreme operating conditions and cleaning protocols, ceramic MF membranes are gradually becoming more employed in the drinking water and wastewater treatment industries when compared with organic and polymeric membranes. Regardless of their many advantages, during continuous operation these membranes are susceptible to a fouling process that can be detrimental for successful and continuous plant operations. Chemical and microbial agents including suspended particles, organic matter particulates, microorganis...

In biodiesel production, downstream purification is an important step in the overall process. This article is a critical review of the most recent research findings pertaining to biodiesel refining technologies. Both conventional refining technologies and the most recent biodiesel membrane refining technology are reviewed. The results obtained through membrane purification showed some promise in term of biodiesel yield and quality. Also, membranes presented low water consumption and less wastewater discharges. Therefore, exploration and exploitation of membrane technology to purify crude biodiesel is necessary. Furthermore, the success of membrane technology in the purification of crude biodiesel could serve as a boost to both researchers and industries in an effort to achieve high purity and quality biodiesel fuel capable of replacing non-renewable fossil fuel, for wide range of applications.

A method for polydimethylsiloxane (PDMS) grafting of alumina powders is described which involves chemical modification of the surface of mesoporous (5 nm) γ-alumina flakes with a linker (3-aminopropyltriethoxysilane: APTES). The systems are analyzed by FTIR, gas adsorption/desorption and TGA. Grafting is proven by FTIR for all cases, meaning that a covalent bond exists between inorganic particle and organic moiety. It is demonstrated that the way of applying APTES hass an effect on the morphology of linker as well as of PDMS. Stability tests on these PDMS grafted alumina show no degradation after 14 days soaking in a wide range of solvents.
Surface modification of metal oxide particles by organic moieties via a chemical reaction can adapt its interfacial properties and renders a high chemical stability of these inorganic-organic hybrids. This validates the use of these materials under severe applications like in membranes for solvent nanofiltration or for protein immobilization and resin modification in e.g. chromatographic applications.

Link: https://drive.google.com/file/d/1j4FG7qlZXzgMV1egShQhHstuCdyoUtvW/view?usp=sharing

The purpose of this work is to investigate pore structure of ceramic membrane fabricated from activated natural zeolite. It is shown that the resulting membrane has quite complex structure with varying type of pores formed and of varying sizes. However, macropore system dominates micro-mesopore system. This is shown by calculating macroporosity of the membrane based on flow test measurement (permeability test) and comparing it with porosity as measured by nitrogen gas adsorption apparatus. In the calculation it’s shown that macropore channel has almost an exponent higher order of magnitude compared to micro-mesopore channel system. A simple calculation on ion adsorption as function of permeability, using effective model lattice was also demonstrated to show how in experimental setup, the quantity of percolation function and open edge probability may be experimentally determined. This experimental quantity may be more of interest in tailoring membrane into specific application with solute specific filtrate.

In this study, a ceramic membrane with a pore size of 0.02μm was used to purify crude biodiesel to achieve biodiesel product that meet both ASTM D6751 and EN 14241 standards specifications. The membrane system was successfully developed and used for the purification process. Process operating parameters such as transmembrane pressure, flow rate and temperature were investigated. Application of central composite design (CCD) coupled with Response Surface Methodology (RSM) was found to provide clear understanding of the interaction between various process parameters. Thus, the process operating parameters were then optimized. The optimum conditions obtained were transmembrane pressure, 2bar, temperature, 40°C and flow rate, 150L/min with corresponding permeate flux of 9.08 (kg/m 2h). At these optimum conditions, the values of free glycerol (0.007wt%) and potassium (0.297mg/L) were all below ASTM standard specifications for biodiesel fuel. In addition the physical properties of biodiesel at the optimum conditions met both ASTM D6751 and EN 14214. This work showed that with ceramic membrane of pore size 0.02μm, biodiesel with high qualities that meet the stringent standards specifications more than those currently in application can be achieved. © 2012 Elsevier B.V.

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An alkali-assisted CEB cleaning method in AnMBR was developed. 0.05-1.30 mmol-NaOH/L had positive impacts on anaerobic biomass under short-term exposure. 10-20 mmol-NaOH/L backflushing significantly reduced membrane fouling rates and slightly improved methanogenic activities. 12 mmol-NaOH/L is cost-efficient and fouling-control dosage.

Nowadays, integrated microfiltration (MF) membrane systems treatment is becoming widely popular due to its feasibility, process reliability, commercial availability, modularity, relative insensitivity in case of wastewater of various industrial sources as well as raw water treatment and lower operating costs. The well thought out, designed and implemented use of membranes can decrease capital cost, reduce chemical usage, and require little maintenance. Due to their resistance to extreme operating conditions and cleaning protocols, ceramic MF membranes are gradually becoming more employed in the drinking water and wastewater treatment industries when compared with organic and polymeric membranes. Regardless of their many advantages, during continuous operation these membranes are susceptible to a fouling process that can be detrimental for successful and continuous plant operations. Chemical and microbial agents including suspended particles, organic matter particulates, microorganis...

In biodiesel production, downstream purification is an important step in the overall process. This article is a critical review of the most recent research findings pertaining to biodiesel refining technologies. Both conventional refining technologies and the most recent biodiesel membrane refining technology are reviewed. The results obtained through membrane purification showed some promise in term of biodiesel yield and quality. Also, membranes presented low water consumption and less wastewater discharges. Therefore, exploration and exploitation of membrane technology to purify crude biodiesel is necessary. Furthermore, the success of membrane technology in the purification of crude biodiesel could serve as a boost to both researchers and industries in an effort to achieve high purity and quality biodiesel fuel capable of replacing non-renewable fossil fuel, for wide range of applications.

There has been upsurge of interests in anaerobic membrane bioreactor (AnMBR) for low-strength wastewater treatments. However, biofouling is still a long-standing problem in the AnMBR because it can increase a frequency of chemical cleaning while shortening membrane life-time. Foulants present in the AnMBR complicate analyses of the membrane fouling due to their wide-ranged particle size distributions present in microbial suspensions and various compressible colloidal materials produced by microbial activities. In general, gas sparging with a biogas produced in the bioreactor or applying very high hydraulic shear conditions along the membrane surfaces is being widely adopted to control biofouling in the AnMBR. However, each physical method requires much high energy consumptions, weakening many advantages of the AnMBR system to achieve energy-positive wastewater treatment. The anaerobic fluidized membrane bioreactor (AFMBR) is to combine anaerobic fluidized bed bioreactor (AFBR) with submerged membrane technology. Granular activated carbon (GAC) particles are used as fluidized media to control membrane fouling by their physical scouring actions and adsorptive capabilities on membrane surfaces. Since GAC particles are fluidized by a recirculation of bulk fluid alone through the reactor, the energy required to reduce membrane fouling can be about one-tenth of it obtained by existing method such as biogas sparing or cross-flow filtration. Nevertheless, both biofouling and energy requirements for fluidization in the AFMBR system can vary significantly depending upon the particle size distributions of the microbial suspensions and GAC sizes applied. This study focuses on combined effect of particle size distributions of the microbial suspensions from the AFBR system and GAC sizes as fluidized media on membrane fouling and energy consumptions using a laboratory-scale AFMBR. Effluents from a pilot-scale AFBR operated in a domestic sewage treatment plant were applied as test solutions to the AFMBR. Our results showed that larger GAC sizes resulted in less membrane fouling in the AFMBR combined with hollow-fiber membranes having 0.03 µm nominal pore size. However, smaller fouling components than 0.1 µm were not affected significantly by GAC fluidization, causing an irreversible membrane fouling. Most of these small colloidal materials consisted of polysaccharide and proteins which are main components in soluble microbial products and/or extracellular polymeric substances. The use of smaller GAC particles which are almost close to powdered activated carbon did not provide any beneficial effect on the reduction of the membrane fouling. As GAC sizes became smaller, the binding interactions between the GAC particles and membrane surface were very strong, accelerating additional external fouling on membrane surface. Energy consumption for fluidization increased exponentially with increasing GAC sizes in the AFMBR system, suggesting that a trade-off exist between fouling control and energy expenditure for GAC fluidization.

Nowadays, integrated microfiltration (MF) membrane systems treatment is becoming widely popular due to its feasibility, process reliability, commercial availability, modularity, relative insensitivity in case of wastewater of various industrial sources as well as raw water treatment and lower operating costs. The well thought out, designed and implemented use of membranes can decrease capital cost, reduce chemical usage, and require little maintenance. Due to their resistance to extreme operating conditions and cleaning protocols, ceramic MF membranes are gradually becoming more employed in the drinking water and wastewater treatment industries when compared with organic and polymeric membranes. Regardless of their many advantages, during continuous operation these membranes are susceptible to a fouling process that can be detrimental for successful and continuous plant operations. Chemical and microbial agents including suspended particles, organic matter particulates, microorganis...

Synthetic solutions assimilating irrigated groundwater containing varying concentrations of humic acid (10 mg/L), saline (10–35 g/L) and metal agents (5–10 mg/L), were processed through a ceramic microfiltration membrane (Sterilox Ltd., 0.5 μm). This was done with enrichment schemes using polymeric coagulants (PDADMAC) applied to enhance the removal of the above-mentioned pollutants. The study was conducted with the scope of investigating the feasibility of sequential and hybrid coagulation and microfiltration as a method of choice for drinking water treatment. Membrane microfiltration is easily scalable into various arrangements, allowing versatility in operation and enrichment schemes, with a relatively lower cost which other treatment practices do not allow. The highest humic acid removal, 91.11% was achieved with hybrid coagulation.

Oxygen–steam biomass gasification produces a high quality syngas with a high H 2 /CO ratio that is suitable for upgrading to liquid fuels. Such a gas is also well suited for use in conjunction with solid oxide fuel cells giving rise to a system yielding high electrical efficiency based on biomass. However, high costs for both oxygen supply equipment and operation are significant challenges for the commercial implementation of this technology. Mixed ionic and electronic conducting (MIEC) membranes can be used for oxygen separation from air at a lower energy consumption compared to cryogenic distillation, especially for small to medium scale plants. This paper examines different configurations for oxygen production using MIEC membranes where the oxygen partial pressure difference is achieved by creating a vacuum on the permeate side, compressing the air on the feed side or a combination of the two. The two configurations demonstrating the highest efficiency are then thermally integrated into an oxygen– steam biomass gasification plant. The energy demand for oxygen production and the membrane area required for a 6 MW th biomass plant are calculated for different operating conditions. Increasing the air feed pressure increases the energy consumption but decreases the membrane area. As an example, for the highest efficiency configuration working at a membrane temperature of 850 C, 6 bar of air feed pressure and 0.3 bar of permeate side pressure, 150 m 2 are needed to generate the oxygen for the 6 MW th plant at an energy consumption of 100 kW h per t O 2 .

Biodiesel is a clean-burning fuel derived from vegetable oils, animal fats, or grease. The chemical structure of commercial biodiesel is fatty acid alkyl esters (FAAE) [1]. Due to renewability, low gaseous emissions and biodegradability, biodiesel is becom-ing very popular in the European Union (EU) which has set an objective to secure for motor biofuels a market share of 20% of the total motor fuel consumption by 2020 [2].