Ceramic Microfiltration Membranes Research Articles

Comparative Assessment of Tubular Ceramic, Spiral Wound, and Hollow Fiber Membrane Microfiltration Module Systems for Milk Protein Fractionation.

The fractionation efficiency of hollow fiber membranes (HFM) for milk protein fractionation was compared to ceramic tubular membranes (CTM) and spiral wound membranes (SWM). HFM combine the features of high membrane packing density of SWM and the more defined flow conditions and better control of membrane fouling in the open flow channel cross-sections of CTM. The aim was to comparatively analyze the effect of variations in local pressure and flow conditions while using single industrially sized standard modules with similar dimensions and module footprints (module diameter and length). The comparative assessment with varied transmembrane pressure was first applied for a constant feed volume flow rate of 20 m3 h−1 and, secondly, with the same axial pressure drop along the modules of 1.3 bar m−1, similar to commonly applied crossflow velocity and wall shear stress conditions at the industrial level. Flux, transmission factor of proteins (whey proteins and serum caseins), and specific protein mass flow per area membrane and per volume of module installed were determined as the evaluation criteria. The casein-to-whey protein ratios were calculated as a measure for protein fractionation effect. Results obtained show that HFM, which so far are under-represented as standard module types in industrial dairy applications, appear to be a competitive alternative to SWM and CTM for milk protein fractionation.

Anti-fouling effect by internal air injection in plate-type ceramic membrane fabricated for the treatment of agro-industrial wastewater

The ceramic microfiltration membrane which composed of membrane body having macro pore and active layer having micro pore was fabricated successfully by the process including the sintering of tape-casted and laminated mixture of zirconia and polyvinyl butyral binder, and re-sintering after screen coating of zirconia. The average pore size and porosity of the fabricated membrane were 0.1855 μm and 40 %, respectively. A novel membrane microfiltration system adopting the fabricated ceramic membrane was also devised for the treatment of agro-industrial wastewater, and the effects of external air sparging and internal air injection were investigated. A significant improvement of permeability by external air sparging was not observed, and the permeate flux was about 20 L/m2/h. Despite the abnormal biomass status resulted from low water temperature and poor maintenance of facility, however, the system operated at the initial TMP of 0.4 bar and internal air injection intervals of 5 min showed excellent permeability of 100 L/m2/h. In addition, although several periodic internal air injections with inverse pressure was carried out, structural defects of fabricated ceramic membrane were not observed. Thus, it confirmed that the anti-fouling effect by optimum back-flushing strategy in fabricated ceramic membrane was effective for stability enhancement of agro-industrial complex wastewater treatment process suffering from maintenance.

Determination of the Optimal Conditions for the Purification of Water from Iron and Manganese by Microfiltration Ceramic Membranes, Based on Theoretical Calculations

Determination of the Optimal Conditions for the Purification of Water from Iron and Manganese by Microfiltration Ceramic Membranes, Based on Theoretical Calculations

Preparation of microfiltration ceramic membranes

The main factors affecting the physicochemical properties of microfiltration ceramic membranes based on natural quartz sand were studied. It was found that samples of large-porous ceramics with a content of 11.0 wt. % of the aluminosilicate binder and 10.0 wt. % of the burning additive are characterized by average pore size of 22±3.02 µm, water capacity of 54±5.0 m3/(h×m2×bar), and tensile strength of 9.0±0.6 bar. The optimal conditions for membrane layers coating were determined, which allowed obtaining microfiltration ceramic membranes with average pore size of 2.3±0.2 µm, water capacity of 26±1.0 m3/(h×m2×bar) and tensile strength of 6.5±0.3 bar.

Changing the conventional clarification method in metal sulfide precipitation by a membrane-based filtration process

The metal sulfide precipitation process is a widely studied technology used to recover metals or remove pollutants from different aqueous sources. However, the conventional clarification stage used to separate the generated precipitates cannot effectively remove them from recovered solutions. Taking this into account, the current study focuses on developing a new separation method applied in metal sulfide precipitates, based on a membrane filtration process. Different operating conditions and metal concentration in the feed solution were evaluated for the separation of copper sulfide precipitates formed from synthetic cyanide solutions in ceramic microfiltration membranes. Results showed attractive values of flux and copper recovery. Flux results ranged between 0.9 L/m2s and 1.2 L/m2s for copper concentrations above 500 mg/L, and copper recoveries resulted closer to 100% at the determined optimal operating conditions (4.5 pH, 120% NaHS stoichiometric dosage, and 2 bar feed pressure). These flux values decreased up to one order of magnitude for diluted copper concentrations, due to a change of aggregation capacity of precipitates. This study has demonstrated that the membrane filtration process can be a suitable alternative for the conventional gravitational clarification, promoting better performance results in terms of equipment capacity, metal recovery, and process safety.

Comparison of Polypropylene and Ceramic Microfiltration Membranes Applied for Separation of 1,3-PD Fermentation Broths and Saccharomyces cerevisiae Yeast Suspensions.

In recent years, microfiltration (MF) has gained great interest as an excellent technique for clarification of biological suspensions. This paper addresses a direct comparison of efficiency, performance and susceptibility to cleaning of the ceramic and polymeric MF membranes applied for purification of 1,3-propanediol (1,3-PD) fermentation broths and suspensions of yeast Saccharomyces cerevisiae. For this purpose, ceramic, titanium dioxide (TiO2) based membranes and polypropylene (PP) membranes were used. It has been found that both TiO2 and PP membranes provide sterile permeate during filtration of 1,3-PD broths. However, the ceramic membrane, due to the smaller pore diameter, allowed obtaining a better quality permeate. All the membranes used were highly susceptible to fouling with the components of the clarified broths and yeast suspensions. The significant impact of the feed flow velocity and fermentation broth composition on the relative permeate flux has been demonstrated. Suitable cleaning agents with selected concentration and duration of action effectively cleaned the ceramic membrane. In turn, the use of aggressive cleaning solutions led to degradation of the PP membranes matrix. Findings of this study add to a growing body of literature on the use of ceramic and polypropylene MF membranes for the clarification of biological suspensions.

Harvesting of Microalgae Biomass Using Ceramic Microfiltration at High Cross-Flow Velocity.

This study aimed to investigate the harvesting of microalgae by microfiltration (MF) on a ceramic membrane at relatively high cross-flow velocity (CFV) of interest for commercial processes. Pilot-scale harvesting was conducted with algal suspensions (Chlorella vulgaris and Tisochrysis lutea (T-Iso)) and algal supernatants (Porphyridium cruentum) to assess the effect of feedstock characteristics and understand flux decline mechanisms. In total recycle mode (C. vulgaris, 1g/L), high steady-state permeation flux around 200L/m2/h was achieved. Total filtration resistance was mainly due to cake resistance (Rc, 57%) and pore adsorption and blocking (Ra, 40%). The process hydrodynamic conditions seemed to have relatively little effect on Chlorella cell integrity. In concentration mode, average permeate flux decreased from 441 to 73L/m2/h with increasing feed concentration (C. vulgaris, 0.25-1g/L); the contribution of Rc decreased (82 to 57%), while that of Ra rose (7 to 40%). With T-Iso suspensions and P. cruentum supernatants at 1g/L, average permeate flux was 59 and 49L/m2/h, respectively, with predominance of Rc and Ra, respectively. Distinct fouling mechanisms were inferred to explain the superior filterability of C. vulgaris. The results show that ceramic membrane MF at relatively high CFV could be a suitable option for harvesting certain microalgae including C. vulgaris.

Fabrication of a Cost Effective Ceramic Microfiltration Membrane by Utilizing Local Kashmir Clay

ABSTRACT In this work, we have reported the preparation of a flat circular ceramic membrane (53 mm diameter and 5 mm thick) by paste casting method from locally available Kashmir clay. The membrane was obtained by sintering the clay disc at 850oC for 5 h. The raw material and the membrane were characterized by X-ray fluorescence (XRF), X-ray diffraction (XRD), thermo-gravimetric analysis (TGA), Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), porosity, and pure water permeability. The XRF and XRD analysis of the clay confirmed the presence of components required for ceramic membrane preparation. Average pore size, apparent porosity, and pure water permeability of the membrane was obtained as 5.88 µm, 24.30%, and 0.9865 l.m–2.h–1.kPa–1, respectively. Chemical stability was carried out by keeping the membrane in HCl (pH=1) and NaOH (pH=14) solutions for one week. The prepared membrane showed excellent chemical resistance in both the media. The overall fabrication cost of the membrane was estimated as 301 $/m2. These results indicate that the clay used in this work could serve as an alternative raw material to kaolin based ceramic microfiltration membranes for cheaper use in different chemical and biochemical processes.

Purification of Alkaline Solutions from Dyes by Microfiltration Ceramic Membranes Made of Clay Minerals Modified by Montmorillonite

We determined the physicochemical regularities of the process of purification of an alkaline solution of a cationic dye (Methylene Blue) and anionic dyes (Direct Brown and Direct Red) using a microfiltration ceramic membrane based on clay minerals, which is dynamically modified with montmorillonite. This membrane retained 99.6% of Methylene Blue at specific productivity of 0.08 m3/(m2 h) at an initial concentration of the dye of 50 mg/dm3, pH0 12.5, P 1.0 MPa, and a permeate selection factor of 80%. The high retention capacity of the ceramic membrane to Methylene Blue is due to the presence of a modifying layer of montmorillonite on its surface, ensuring the adsorption of dyes in the form of an additional retention gel-like layer of dye associates. The modified microfiltration ceramic membranes made of clay minerals, developed at the Dumansky Institute of Colloidal Chemistry and Water Chemistry, National Academy of Sciences of Ukraine, are comparable to modified microfiltration membranes of oxide ceramics from Rauschert (Germany) in the efficiency of water purification from cationic dyes but are much more productive and cheaper than the latter. Under similar conditions, the modified membrane of clay minerals also showed a high retention capacity to Direct Brown and Direct Red anionic dyes. The mechanism of their retention is associated with the electrostatic repulsion of like-charged anions of dyes and montmorillonite particles. A clay-based ceramic membrane modified with montmorillonite is proposed for the pretreatment of alkaline washing solutions of banknote factories.

Low-cost ceramic microfiltration membranes made from Moroccan clay for domestic wastewater and Congo Red dye treatment

Low-cost ceramic microfiltration membranes made from Moroccan clay for domestic wastewater and Congo Red dye treatment

Preparation and characterization of ceramic membrane using waste almond shells as pore forming agent

In this work, a kaolin based ceramic microfiltration membrane prepared by uniaxial compaction method using locally available waste almond shells as a natural pore-forming agent is reported. The powder (60ASTM Mesh) prepared from waste almond shells was added to the raw mix as a pore-forming agent. The disc prepared from the raw mix at 150 MPa was sintered at 850℃ for 4 h to obtain the membrane. The raw material and the membrane were characterized by X-ray diffraction (XRD), thermogravimetric analysis (TGA), Fourier transform infrared (FT-IR) spectroscopy and field emission scanning electron microscopy (FE-SEM). The pore diameter and porosity of the membrane were obtained as 0.290 μm and 46.45% with good chemical stability. The fabrication cost of the membrane based on the cost of raw material was estimated to be Rs. 2083.33/m2. These results show that the almond shells can be utilized as an economical and green material in the fabrication of low-cost ceramic membranes.

Ozonation-assisted electro-membrane hybrid reactor for oily wastewater treatment: A methodological approach and synergy effects

Abstract Wastewater produced from oil and gas industries contains high levels of organic and inorganic pollutants in the form of emulsions sized below 10 μm. The beneficial reuse of oily wastewater requires advanced treatment methods to remove these emulsions and promote cleaner production. This work has attempted to investigate the hybridization of electrocoagulation (EC) process, ceramic microfiltration membrane, and ozonation as a one-pot solution for the treatment of oily wastewater. The variables in this study included hydraulic retention time (HRT), aeration, current density (CD), mode of power supply, and initial pH of the sample. Aerated electro-membrane reactor contributed to a maximum COD reduction of 18.0% as opposed to 53.1% for the ozonated reactor. The effectiveness of the novel hybrid reactor could be attributed to the enhancement of electrocoagulation process by the ozone, which facilitated size-exclusion by the submerged membrane. Scanning electron microscope (SEM) and energy-dispersive X-ray spectroscopy (EDS) were performed to characterize the generated foam, electrodes, and sludge. The present findings indicate that the ozonation-assisted electro-membrane hybrid method has the potential to be employed for the treatment of oily wastewater.

Elaboration and properties of low-cost ceramic microfiltration membrane from local Tunisian clay for wastewater treatment

Abstract This study focused on the development and preparation of a microfiltration membrane, based on a low-cost natural Tunisian clay powder, deposited on macro-porous ceramic support. The deposit was made through a dip-coating technique, followed by a drying process and sintering at 700 °C. Results revealed that the obtained membrane was characterized by a good adhesion between the membrane layer and the ceramic support, an average pore diameter of 0.34 mm, and a porosity of 39%. This membrane was applied in the treatment of wastewater generated by the wastewater treatment plant of Sfax, Tunisia. The performances in terms of permeate flux and efficiency were determined in order to reduce the pollutant content expressed in terms of turbidity, biochemical oxygen demand (BOD5), and suspended matter (MES). Results showed an MES retention value of about 15%, and turbidity and BOD5 retention rate of 99% and ~100%, respectively.

A novel monolithic mullite microfiltration membrane for oil-in-water emulsion separation

Monolithic ceramic microfiltration membranes made up of an interlocking network of mullite crystals have been developed from low-cost raw materials, consisting of China clay, AlF3·3H2O and Al2O3. The characteristics of the developed membranes have been studied. The membrane made from clay+40 wt% AlF3·3H2O powder mixture with 10 wt% Al2O3 displayed excellent properties, with apparent porosity of 64%, median pore diameter of 0.3 μm, flexural strength of 43 MPa, and pure water permeance of 1031 L/m2 h bar. The membrane also displayed excellent pore connectivity and chemical stability owing to the crosslinked needle-like mullite microstructure. The performance of the mullite microfiltration (MF) membrane in oil-in-water emulsion separation was studied with three test solutions having oil concentrations of 200 mg/L, 500 mg/L and 1000 mg/L. The membrane showed excellent permeate flux of more than 200 L/m2. h at a transmembrane pressure of 2 bar and high oil rejection of more than 96% with all the feed concentrations. The fabrication of the monolithic mullite MF membrane in comparison to the conventional asymmetric ceramic MF membranes is highly economical and can be used as a cost-effective alternative for oil-in-water emulsion separation.

Pilot‐scale microalgae harvesting with ceramic microfiltration modules: evaluating the effect of operational parameters and membrane configuration on filtration performance and membrane fouling

AbstractBACKGROUNDMembrane fouling is one of the major drawbacks in microalgae harvesting that prevents the widespread application of membrane filtration. This study investigates the effects of operating parameters on the filtration performance and the fouling phenomenon of a pilot‐scale microfiltration (MF) system equipped with different ceramic membranes for Chlorella vulgaris culture harvesting.RESULTSA higher permeate flux was obtained with increasing the transmembrane pressure, resulting in lower irreversible and reversible filtration resistances. On the other hand, at a higher crossflow velocity above 4 m s−1, a high amount of extracellular organic matter (EOM) released by microalgal cells led to a higher irreversible resistance which, in turn, caused severe membrane fouling and a lower filtration flux. Furthermore, the membrane configuration and pore size have also significantly affected the permeate flux. Compared to the tubular membranes, and regardless of pore sizes, the multichannel MF membrane (pore size: 0.2 μm) exhibited a higher permeate flux that resulted in lower membrane resistances due to the lower release of EOM by microalgae cells. Moreover, the tubular membrane (pore size: 0.8 μm) showed a higher flux reduction with higher pore size because of the increase in the irreversible resistance with a high amount of EOM release.CONCLUSIONThe results revealed that the amount of EOM significantly associated with filtration conditions plays an important role in membrane fouling control. Considering the membrane configurations, the multichannel ceramic MF membrane (pore size: 0.2 μm) demonstrated a higher permeate flux due to its lower fouling property. © 2020 Society of Chemical Industry (SCI)

Low-cost ceramic microfiltration membrane made from natural phosphate for pretreatment of raw seawater for desalination

A novel ceramic microfiltration (MF) membrane was prepared from natural phosphate and its properties were thoroughly characterized. An investigation of the effect of sintering temperature on the features of phosphate membrane was carried out in the range from 900 to 1100 °C. The optimized membrane sintered at 1000 °C exhibits 697 L h−1 m-2 bar−1 of permeability, 25.6 % of porosity, 0.26 μm of average pore size and 19.7 MPa of flexural strength. When evaluated for filtration of raw seawater as a potential pretreatment for reverse osmosis desalination, the prepared membrane reduced total organic carbon (TOC) and turbidity by 73 and 98 %, respectively, as well as reducing silt density index (SDI) from 5.41 to 3.25. Furthermore, the fouling mechanism and the flux recovery were also studied. Finally, simple cleaning of the prepared membrane performed after the MF experiment led to recover 74 % of its original water flux.

Ceramic Microfiltration Membranes in Wastewater Treatment: Filtration Behavior, Fouling and Prevention.

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, microorganisms and heavy metals mainly contribute to fouling, a complex multifactorial phenomenon. Several strategies, such as chemical cleaning protocols, turbulence promoters and backwashing with air or liquids are currently used in the industry, mainly focusing around early prevention and treatment, so that the separation efficiency of MF membranes will not decrease over time. Other strategies include combining coagulation with either inorganic or organic coagulants, with membrane treatment which can potentially enhance pollutants retention and reduce membrane fouling.

Low-cost ceramic membrane made from alumina- and silica-rich water treatment sludge and its application to wastewater filtration

Drinking water treatment sludge (DWTS) was used for the preparation of ceramic microfiltration membrane. The DWTS powder was firstly characterized to determine its chemical and mineralogical composition, and to understand its thermal behavior. DWTS powder was mixed with clay as binder and starch as porosity agent, then pressed to shape flat membrane, and sintered at different temperatures from 950 to 1150 °C. The optimal sintering temperature (1050 °C) provides ceramic membrane with a porosity of 46.7%, a pore size of 0.92 μm, a mechanical strength of 14.5 MPa and a permeability of 724.5 L/h.m2.bar. This membrane was successfully used to clarify a synthetic baking powder suspension and an textile effluent. DWTS-based membrane was able to remove completely the turbidity from feeds, to reduce significantly the chemical oxygen demand (COD), and to discolor completely textile wastewater. Furthermore, four empirical models were applied to describe the fouling mechanism occurred during filtration experiments.

Synthesis, characterization and performance studies of kaolin-fly ash-based membranes for microfiltration of oily waste water

The present study deals with the synthesis, characterization, and performance evaluation of low-cost porous ceramic microfiltration membranes for separation of oily waste water. Ceramic membranes were synthesized following paste-casting method using three different ratios of kaolin to coal fly ash, in combination with a few selected suitable pore - formers and binders like calcium and sodium carbonate, boric acid, and sodium metasilicate. The synthesized membranes were characterized using the field emission scanning electron microscope (FESEM), X-ray diffraction (XRD), atomic force microscopy (AFM), thermogravimetric analysis (TGA), and water permeation tests with the objective of investigating the influence of sintering temperature (750 °C–900 °C) and precursor ratio on the microstructural evolution of the fabricated membranes. Three varying concentrations of oil-in-water (O/W) emulsions (100, 200, and 300 mg/L) prepared using a typical crude oil collected from an oil field located in Digboi, India was used as a representative sample and tested for the microfiltration studies. A fabricated membrane with a porosity (~34.36–39.0%), pore size (~0.65–1.81 μm) showed an excellent separation efficiency of 96.7–99.5% with a permeate flux around ~ 24.3 × 10−5 m3 m−2 s−1. The flux decline mechanism was analyzed using the pore blocking models, and it was observed that the cake filtration model followed by the intermediate pore-blocking model were the best - fitted models as compared to others to describe the permeate flux data. The fabricated kaolin-fly ash-based membranes exhibited good permeability and separation efficiency characteristics, which suggest its suitability for microfiltration of oily waste water from oil exploration and refinery industries.

Fabrication and Characterization of Ice Templated Membrane Supports from Portland Cement.

Porous ceramic membranes for aqueous microfiltration and ultrafiltration processes suffer from the high-costs of material and processing. The latter is mainly due to the high-temperature sintering step. In this work, cement-based membrane supports from ultrafine Portland cement are studied as a low-cost alternative to traditional oxidic ceramic supports. An environmentally friendly freeze-casting fabrication route is applied for the fabrication of porous membrane supports. Cement membrane supports are becoming mechanically stabile after hydration reaction of cement with water, which does not require any high-temperature sintering step as in a conventional ceramic membrane fabrication process. This fabrication route, which is sintering-free, decreases the cost and environmental impact of the membrane fabrication process by eliminating extra energy consumption step during sintering. The Archimedes method, scanning electron microscopy (SEM), micro-computed tomographic (µCT), and mercury porosimetry characterize the membrane supports in respect to open porosity, pore size distribution, morphology, and connectivity. The flexural strength of the 3 mm thick membranes is in the range from 1 to 6 MPa, as obtained by the ring-on-ring tests. The obtained membrane supports possess porosity in the range between 48 and 73% depending on fabrication conditions (cooling rate and the solid content, as determined by Archimedes method enabling water flux in the range between 79 and 180 L/(h·m2) at 0.5 bar transmembrane pressure difference and 3 mm membrane thickness.