Ceramic Microfiltration Membranes Research Articles

Removal of Natural Organic Matter Fractions by Kaolin/Fly Ash Ceramic Microfiltration Membrane in Drinking Water: Insights from a Laboratory Scale Application

AbstractThe high cost of precursor materials has hindered commercialization of ceramic membranes (CM). In this work, a microfiltration ceramic disc (≈50 mm in diameter and 4 mm thick) is prepared from low‐cost materials, kaolin, and fly ash (≈67 and 26 wt.%, respectively) by pressing at 200 bar and calcining at 900 °C. Membrane characterization involved physicochemical properties, NOM removal efficiency, and fouling propensity analysis. Furthermore, the efficiency of the CM is tested on samples collected from four drinking water treatment plants (DWTPs) in KwaZulu‐Natal Province of South Africa. The NOM removal efficiencies ranged from 18.5–33.4% higher than that achieved by the sand filtration step of all the DWTPs. Fluorescence excitation‐emission matrix (FEEM) studies show dominance of terrestrial humic‐like and fulvic‐like NOM fractions in the raw water and are amenable to removal by CM at all the DWTPs (up to 64.7% higher than removal by sand filters at the respective plants). This study demonstrates the utility of ceramic membranes fabricated from rudimentary materials and presents an opportunity to upscale and retrofit the technology to target the removal of NOM fractions at conventional drinking water treatment plants.

Treatment of digested blackwater using a submerged microfiltration membrane system or a drum filter

After energy recovery from blackwater via anaerobic digestion, technologies such as struvite precipitation and ammonia stripping can be used to enhance nutrient recovery. However, the presence of suspended solids, organics and metals, can negatively impact the nutrient recovery processes. This study examined the treatment of digested blackwater, applying either a ceramic microfiltration membrane or a drum filter, operating in parallel in a source-separated wastewater plant. The digestate as well as the permeates from the membrane and drum filter were sampled regularly and evaluated. In general, the ceramic membrane proved to be more efficient in improving the quality of digested blackwater in comparison to the drum filter. The ceramic membrane reduced total suspended solids to below the detection limit, while the drum filter achieved 74 % removal. The membrane removed 74 %, 85 % and 76 % of TOC, BOD7 and COD-Cr, respectively, higher than the corresponding treatment with the drum filter, which removed 41 %, 42 % and 34 %, respectively. No significant differences in phosphate and ammonium concentrations (P-value = 0.05), before and after both treatment methods were observed. The membrane removed particulate-bound metals (As, Cd, Cr, Cu, Ni, Pb and Zn) up to 25 %, 95 %, 87 %, 95 %, 66 %, 90 % and 98 %, respectively. The drum filter achieved lower removal for particulate-bound As, Cd, Ni, Pb and Zn for 25 %, 79 %, 44 %, 56 % and 86 %, respectively. The removal of metals is critical to maintain struvite purity and prevent the struvite contamination due to co-precipitate of these metals.

Effect of silicon powder dosage on the microstructure and performance of SiC/Si3N4 composite ceramic microfiltration membranes

The SiC/Si3N4 composite ceramic microfiltration membranes were fabricated using the in-situ nitridation process of silicon powder at 1350 °C, utilizing SiC powder and silicon powder as the raw materials. The effects of silicon powder dosage on the phase composition, basic physical properties, pure water flux, pore size distribution, and microstructure of membrane materials were investigated. With an increase in the silicon powder quantity from 5 wt% to 20 wt%, the flexural strength of the membrane materials increased from 6.6 MPa to 42.4 MPa, while the apparent porosity remained stable at 37.0%–39.0 %. The experimental results indicated a substantial correlation between the pore size distribution and the pure water flux. As the average pore size of the ceramic membranes decreased from 463.87 nm to 132.68 nm, the pure water flux gradually decreased from 265.99 L/(m2⋅h⋅bar) to 50.34 L/(m2⋅h⋅bar). The systematic investigation reveals that the Si3N4 binding phase, generated from the in-situ nitriding reaction of silicon powder, is the primary factor responsible for enhancing the mechanical properties of the membrane material. The process of in-situ nitriding silicon powder is accompanied by an increase in volume, which is beneficial in filling and refining the pores. Moreover, the formation of silicon nitride whiskers during the nitriding process can enhance the material's mechanical properties and further divide and refine the pores.

Process efficiency assessment of turbidity removal from tigris river using microfiltration membranes

The current study aims to use microfiltration membrane units instead of using traditional treatment methods (flocculation and coagulation) to enhance water treatment efficiency and lower operational and fixed costs. Specifically, it explores using a polypropylene membrane with a pore size of 1 µm and a ceramic membrane with a pore size of 0.5 µm to remove turbidity, total suspended solid TSS, and Escherichia coli bacteria from the Tigris River water within Baghdad. An experimental study compared the removal efficiency of real and simulated Tigris River water with different turbidity for polypropylene and ceramic membranes. Operational parameters such as initial turbidity concentration, temperature, flow rate, and membrane fouling were studied as a function of time. Also, two operating methods, dead-end, and crossflow, were discussed regarding the removal efficiency of suspended solids, turbidity, and Escherichia coli bacteria 65 %, 91 %, and 99 %, respectively, for the polypropylene membrane. And 75 %, 97 %, and 100 % for the ceramic membrane. The results of the current study indicate that ceramic membranes are the most susceptible to contamination by fouling, but at the same time, they are the most resistant and have the highest rate of removal efficiency than the polypropylene membrane. In addition, the crosse flow operation is better than the dead-end operation and is also considered a way to reduce the fouling that occurs in the membrane filtration. Microfiltration in general can achieve economic profit and minimal environmental impact, and ceramic microfiltration membranes in particular can achieve high-quality water.

Enhancing microfiltration membrane efficiency for treating industrial wastewater derived from sugar industry waste through Doehlert design optimization

To address the challenges of treating industrial wastewater, the scientific community must engineer novel membrane materials that prioritize innovation, cost-efficiency, and environmental sustainability. The present study describes the fabrication and characterization of a newly designed, economically viable planar microfiltration ceramic membrane made from sugar scum and indigenous Moroccan clay. Utilizing the Doehlert design-based Response Surface Methodology, optimization of preparation conditions was conducted to investigate the effects of sugar scum quantity (5–30 %), sintering temperature (800–1000 °C), and sintering time (60–180 min) on mechanical strength, water absorption, and porosity. The enhanced membrane displays a compressive strength of 56.10 MPa, a porosity of 42.71 %, a permeability of 1246 L h−1 m−2 bar−1, and an average pore size of 0.88 µm. Additionally, it demonstrates outstanding resistance to chemical corrosion in basic environments. The optimal clay membrane underwent industrial wastewater filtration and performed admirably as a microfiltration membrane. It had impressive removal rates of 98.26 % for turbidity, 62.86 % for chemical oxygen demand (COD), and 46.14 % for electrical conductivity. Furthermore, the cleaning procedure restored 88 % of the membrane's original water permeability.

Fabrication and application of highly permeable ceramic membranes: Membrane-forming mechanism, pore structure, separation performance and fouling mechanism analyses

High separation efficiency and satisfactory economic benefits are of great importance for ceramic membranes in the field of water treatment. Herein, microfiltration ceramic membrane with high permeability and selectivity was prepared in one-step (dip-coating and sintering) by sacrificial-interlayer method. The membrane-forming mechanism, effect of temperature on the morphology and pore structure, separation performance, fouling mechanism, and regeneration performance of the ceramic membranes were systematically investigated. The results show that membrane-forming mechanism of the membranes largely depends on film-coating filtration. The membrane with a mixture of nanocellulose crystals and graphene oxide as sacrificial interlayer (C1G1) and sintered at 1100–1300 °C possessed smooth surface. The open porosity and average pore size increased, and the pore size distribution became broader as the temperature increased. Moreover, the sacrificial-interlayer membrane sintered at 1300 °C (mA4S-C1G1) possessed suitable porosity (53.4%) and average pore size (200 nm), high permeance (4828 L·m−2·h−1·bar−1), which was larger than that of the membrane without sacrificial interlayer, manifesting that C1G1 could prevent the penetration of membrane-forming particles into support. The final fouling mechanism of mA4S-C1G1 was cake filtration, although complete pore blocking, standard pore blocking, intermediate pore blocking also involved in the initial stage. In addition, the oil rejection rate (∼97%) and steady-state feed flux (810–1154 L·m−2·h−1) of mA4S-C1G1 was high, and it also possessed good regeneration performance.

Removal of heavy metals from mine water using a hybrid electrocoagulation-ceramic membrane filtration process

Mining operations must account for increasingly stringent wastewater discharge limits for various contaminants, such as heavy metals and suspended solids. In the treatment of metal-bearing wastes, electrochemical processes, including electrocoagulation (EC), are gaining popularity. At large scales, EC processes can be hindered by considerable amounts of flocculants and by sedimentation tank sizes required to properly operate. This work sought to address these concerns by evaluating EC in mine water treatment using a pilot system coupled with ceramic membrane microfiltration (MF) and ultrafiltration (UF). The use of MF and UF after EC allows for the removal of suspended solids without needing a flocculation-sedimentation process. EC evaluation was performed using field samples of mine water from a North American concentrator. Under optimal conditions, EC removed over 95 % of Cr, Co, Cu, Fe, Mn, Ni, Pb, Ti and Zn from the mine water. Effluent from EC was used as feed in MF and UF processes with ceramic membranes. The tested membranes rejected 100 % of suspended solids from the EC effluent. Permeate from the membranes was free of solids and possessed turbidities of 0.05–0.15 NTU. Filtrate from the hybrid process satisfied environmental regulations for heavy metal concentrations, offering new opportunities for reuse or discharge. The hybrid process applied in this work can thus be used in mining operations to safely discharge their water, and/or to increase their water recirculation due to environmental concerns and water shortage.

Preparation of low‐cost peridotite ceramic microfiltration membrane for treating industrial wastewater

AbstractThe aim of this work is to fabricate a low‐cost ceramic microfiltration (MF) membrane made from a new geomaterial named peridotite. The membrane was prepared by uniaxial pressing and followed by sintering. The effect of sintering temperature, in the range of 1100–1225°C, on the permeability, porosity, mechanical strength, and pore size was investigated. The optimized MF membrane sintered at 1200°C exhibits 1198.9 L h−1 m−2 bar−1 of permeability, 36.41% of porosity, 12.9 MPa of mechanical strength, and 1.56 µm of pore size. The prepared membrane was used for the MF treatment of dairy wastewater. It was found that the membrane is able to remove 88.56% and 69.54% of turbidity and chemical oxygen demand, respectively. Furthermore, the cost of the peridotite membrane was estimated to be $10.3 m−2.

Performance Investigation of Surface Modified Ceramic Microfiltration Membranes of Ionic Water Treatment

Performance Investigation of Surface Modified Ceramic Microfiltration Membranes of Ionic Water Treatment

Construction of asymmetric ceramic membranes with identical source interlayer on fly ash support by dip-coating

As a highly efficient separation technology, ceramic membranes have been widely applied. The use of fly ash to prepare low-cost ceramic membranes has garnered significant attention in recent years. However, challenges remain in the preparation of asymmetric ceramic membranes with high performance. This study presents an efficient approach to fabricating asymmetric ceramic membranes with an identical source interlayer on fly ash supports using the dip-coating method. The alumina selective layer was co-sintered with the optimized interlayer at 1000°C. The average pore size of the asymmetric ceramic microfiltration membrane was approximately 120 nm, and the pure water permeance reached 870 L·m−2·h−1·bar−1. The ceramic microfiltration membrane demonstrated high efficiency in separating oil-in-water emulsions, achieving a stable permeance of 130 L·m−2·h−1·bar−1 and a TOC removal rate above 99 %. This work provides an efficient and effective construction method for producing fly ash-based ceramic membranes with high performance.

A new ceramic microfiltration membrane based on olive seeds: development and characterization

ABSTRACT The development of low-cost methods for wastewater treatment and the separation of oil-in-water emulsions is of considerable significance. Recently, natural material-based, inexpensive membranes have become a hot area of research. In this work, natural olive seeds were used to develop a novel ceramic membrane support. With the oil filtration process in place, the choice was reached to utilize the olive kernels’ beneficial qualities best. The process involved blending plastic paste with water and organic ingredients, followed by extruding the resulting paste into a porous tubular. After firing at 200 °C/2 h, the membrane's water permeability and porosity were 1,852 L/h m2 bar and 45%, respectively, and its average pore width varied from 2 to 15 μm. The efficiency of the microfiltration membrane in separating oil-in-water emulsions was assessed using two test solutions containing oil concentrations of 500 and 1,000 mg/L. Under a transmembrane pressure of 1 bar, the membrane exhibited exceptional permeate flux exceeding 200 L/m2 h, along with a high oil rejection rate of over 96% across all feed concentrations.

Combination of TiCl3 reduction/coagulation and ceramic membrane filtration for heavy metal complex removal

Ni-EDTA is a common heavy metal complex found in electroplating wastewater. As heavy metal complexes are stable and highly toxic, it is essential to develop efficient strategies to remove. In this work, TiCl3 coagulation and ceramic microfiltration membrane were combined in the removal of Ni-EDTA. Based on the results, this combinative process exhibited a high Ni-EDTA removal efficiency. When compared to employing the TiCl3 coagulation process only, the combinative process improved Ni2+ and TOC removal efficiencies from 91 % to 97 % and from 60 % to 93 %, respectively. Furthermore, it was found that the in-situ formed titanium hydrolysates possessed good adsorption for EDTA and Ni-EDTA, with maximum capacities reaching 713 mg/g and 213 mg/g, respectively, which also enabled the cake layer a considerable secondary removal for TOC. Mechanistic investigations confirmed that the reducibility of Ti3+ contributed to both Ni-EDTA and EDTA removal. In the presence of Ti3+, Ni-EDTA was decomplexed and the released Ni2+ was reduced to Ni0 synchronously. Meanwhile, some dissociated EDTA would combine with oxidized Ti4+ to form Ti-EDTA and ultimately promote the formation of TiO2 crystals. The formation of the insoluble chelate Ti-EDTA and the adsorption by surface hydroxyl of TiO2 were the key reasons for the efficient removal for released EDTA. This work provides a new approach for the decomplexation and harmless separation of heavy metal complexes.

In vitro digestion analysis of soft candy containing peptide-zinc chelates derived from low-fluoride protein hydrolysates of Antarctic krill (Euphausia superba) powder

This study developed a soft candy with peptide-zinc chelates using low-fluorine protein hydrolysates derived from Antarctic krill powder. To achieve this, the enzymatic hydrolysis conditions of the protein isolates were optimized through single-factor experiments. Protein hydrolysates were used to produce Antarctic krill peptides (AKP) through ceramic membrane microfiltration at various pressure levels. AKP-zinc chelates (AKP-Zn) were prepared by mixing AKP and zinc sulfate, subsequent to characterized the resulting complex. Finally, we examined the tolerance of AKP-Zn and soft candy containing AKP-Zn (SC-AKP-Zn) to simulated gastrointestinal digestion in vitro. The optimal enzyme mix was a 1:1 ratio of alkaline and flavored protease, with 4000 U/g enzymes, pH 7.5 and 3 h, and the ceramic membrane microfiltration increased the protein content in AKP by approximately 85.34 ± 3.54 %. Characterization showed that AKP effectively interacts zinc ions through bonding with oxygen and nitrogen atoms, helps the strength of AKP-Zn in various pH levels and simulated digestive systems. AKP-Zn and SC-AKP-Zn showed higher bioavailability compared to zinc sulfate and zinc gluconate. These results provide a solid theoretical foundation for creating ready-to-eat food products with AKP-Zn and offer new insights into the potential applications of Antarctic krill proteins.

Construction of anti-fouling ceramic tubular membranes with corrugated inner surfaces using DLP 3D printing

The challenge of membrane fouling persistently hinders the advancement of membrane technology. The construction of patterned membrane surfaces is anticipated to mitigate the effects of membrane fouling significantly. In this study, ceramic microfiltration membranes with corrugated patterns were fabricated by 3D printing combined with the dip-coating process. To assess the impact of surface patterning on ceramic membrane performance, we initially compared the pore size and pure water flux between straight and corrugated membrane tubes. Both configurations exhibited similar parameters: a support pore size of approximately 1 μm, a membrane layer pore size of about 110 nm, and a pure water permeance of around 950 L m−2 h−1·bar−1. The corrugated ceramic membranes demonstrated superior anti-fouling properties compared to their straight counterparts during the filtration of nanoparticle suspensions, oil-in-water emulsions, and bacterial suspensions. Specifically, under a nanoparticle suspension concentration of 2000 ppm, a transmembrane pressure of 0.2 MPa, and a flow rate of 1.0 m s−1, the corrugated membrane achieved a stable flux of approximately 1.7 times greater than that of the straight membrane. Furthermore, we explored the effects of surface patterning on fluid dynamics through numerical simulations. The enhanced turbulence dissipation rate in the patterned membrane tubes suggests increased surface turbulence and an improved capacity to remove contaminants. This research offers novel insights into the development of ceramic membranes with enhanced anti-fouling capabilities for water treatment.

Phytoremediation capability of Anabaena sp. for high organic and chromium-loaded wastewater in membrane bioreactors.

The efficiency of Anabaena sp. was analyzed for the phytoremediation of wastewater loaded with organic matter and heavy metals like chromium. Simulated wastewater was contaminated with chromium. A side-stream membrane bioreactor was used for the treatment of wastewater. A feed tank of 20 L capacity was used with a stirring arrangement. A ceramic microfiltration membrane composed of clay and alumina was obtained from Johnson & Johnson. The removal efficiency of chemical oxygen demand, biochemical oxygen demand, and chromium was evaluated. The process was used for algae harvesting and wastewater treatment. About 92% of chemical oxygen demand (COD), 98% chromium, and oil and grease were completely removed. Membrane fouling was explained by the pore blocking and cake resistance model. Stress in algal cells was determined from the superoxide dismutase (SOD) and catalase (CAT) analysis. The lipid content of algal cells was measured.

Integrated Approach: Characterization, Application of Alumina Kaolin Membrane for Glycerol Separation in Biodiesel Production, and Flux Recovery Strategies

The transesterification process used for biodiesel production yields glycerol as a prominent byproduct. Given glycerol's adverse effects on engine performance and longevity, regulatory standards, such as those set by SNI and international authorities, restrict free glycerol content in biodiesel to below 0.02 wt.% or 200 ppm. Consequently, the removal of glycerol has become a critical step in biodiesel production. Traditional purification methods are energy-intensive and generate substantial wastewater, prompting the exploration of alternative solutions like membrane separation technology. Ceramic microfiltration membranes, renowned for their exceptional thermal, chemical, and mechanical durability, have emerged as a prominent choice. The development and application of a cost-effective Alumina-Kaolin ceramic microfiltration membrane for glycerol removal in biodiesel signify a promising advancement in water purification processes. The current study was conducted to evaluate the microfiltration performance of the Alumina-Kaolin ceramic membrane, investigate the impact of the membrane’s microstructure on separation performance, and explore cleaning strategies aimed at enhancing flux recovery ratio (FRR). The microstructure analysis through SEM and BET demonstrated pores in the membrane, featuring a 3.375 m2/g surface area, 30.367 % porosity, and 0.18 μm pore size. Several tests employed using different glycerol and water concentration in the feed of 1000 ppm, 5000 ppm and 10000 ppm. The evaluation gave high glycerol rejection rates of 92.07%, 98.52% and 98.94% for the respective feed concentrations with the permeate flux of 65.42 [l/(m2h)], 61.09 [l/(m2h)] and 52.91 [l/(m2h)] respectively. The microstructure of alumina-kaolin membrane could separate the larger particles of glycerol-water droplets and gave high separation performance. As the flux decline ratio increased (from 2.13% to 20.86%) due to rising glycerol concentration (1,000 to 10,000 ppm), cleaning became crucial for flux recovery. Employing various agents, benzalkonium chloride notably enhanced alumina-kaolin flux recovery ratio (FRR) to 98.17%.

Preparation and characterization of low-cost ceramic microfiltration membranes for water treatment

This work presents the preparation of microfiltration (MF) membranes deposited on highly porous supports tailored for microfiltration applications. The supports were prepared from local Algerian clays and calcium carbonate, selected for their abundant availability. Subsequently, these supports underwent coating with microfiltration membrane using the slip casting method employing the same clay powder. The resulting membrane, sintered at 1100?C, exhibited desirable attributes including a thickness of approximately 27 ?m and an average pore size (APS) value of about 0.42 ?m, coupled with notable adhesion between the support and the membrane. Furthermore, physicochemical and microbiological tests were conducted on water samples to confirm the effectiveness of the membrane in microfiltration. The results show that the membrane is highly effective in removing turbidity, with a rejection rate of approximately 99%. The pH and conductivity of the water remain stable during filtration. Additionally, the membrane demonstrates significant efficiency in removing heavy metals, with rejection rates of about 68% for iron and 90% for aluminium, as well as it is effective in removing specific bacteria from water.

A novel and simple fabrication method for a biomimetic-inspired lath-structured ceramic microfiltration membrane for the treatment of oil-in-water emulsions

Ceramic membranes have been widely explored as competent alternatives to traditional polymeric membranes for treating oily wastewater. Despite the exceptionally high rejection rate (>90 %) of oil–water (O/W) emulsions, membrane fouling is an inevitable phenomenon that limits the separation efficiency of ceramic membranes. Biomimetic technology, known as the lotus effect, has attracted attention as a groundbreaking method for reducing membrane fouling. However, it is difficult to control the nanostructured surfaces of ceramics, while polymer fabrication is facile. In this study, we developed a novel and simple method to fabricate an α-alumina (Al2O3) microfiltration (MF) membrane with a Nepenthes pitcher plant-like microstructure. The surface roughness of the biomimetic membrane was 286 nm, which was approximately twice that of a normal ceramic membrane. Accordingly, the oil contact angle increased from 88.84 to 128.51°. The novel biomimetic membrane showed high efficiency with an emulsion permeability of 44.1 LMH/bar, a flux recovery of 90.91 %, and an oil rejection rate of 99 %.

A self-cleaning thermocatalytic membrane for bisphenol a abatement and fouling removal

Thermocatalytic, ceramic microfiltration membranes for continuous micropollutants removal and simultaneous degradation of organic fouling were synthesized by integrating a Sr0.85Ce0.15FeO3 (SCF) perovskite in alumina membranes and tested for the bisphenol A (BPA) abatement under different experimental conditions. Scanning electron microscopy (SEM) and Energy Dispersive X-ray spectroscopy (EDX) characterization techniques were used to characterize the samples. The effect of water flux, BPA concentration and temperature on the BPA and fouling removal was investigated in detail. Up to 55 % of BPA was removed by filtration of a 9.6 mg L−1 BPA solution at 40 °C and a flux of 25 LMH. Degradation studies with BPA feed concentrations of 3.4, 5.5 and 9.6 mg L−1 showed higher degradation rate by the membrane with higher concentrations of BPA. Furthermore, the rate of BPA degradation increases with lower permeate flux, due to the longer retention time of pollutant in the membrane. Membranes were fouled with humic acid to study the thermocatalytic fouling removal. After fouling, membranes were rinsed to remove external, removable fouling, which was followed by 20–120 min of thermal treatment at 40 °C. This showed up to complete recovery of permeability by reduction of hydraulic resistance from the internal fouling in the membranes. No effect of heat treatment was observed for fouled non-functionalized membranes. Hence, the novel membrane studied in this article is a promising solution for simultaneous degradation of micropollutants and recovery of permeability during filtration, e.g. in wastewater treatment.

Maximizing Efficiency and Affordability with Ceramic Membranes for Enzyme Immobilization

AbstractLow‐cost ceramic microfiltration membranes were explored for immobilizing lipases. Expensive commercial ceramics (e.g., alumina, zirconia) have advantages like chemical robustness, but high sintering temperatures limit their usability. To overcome this, researchers used Fuller's earth clay with rice husk ash to create cost‐effective membranes. However, fewer reactive sites on ceramic surfaces hinder enzyme immobilization. To address this, 3‐aminopropyltriethoxysilane and glutaraldehyde activated the membrane for covalent lipase binding. The immobilized membrane retained activity for over five 1‐h reaction cycles with a minimal performance decline of around 60 %. After five cycles, it retained over 40 % of the initial activity. These results show promise for using low‐cost ceramic membranes in various industries, such as in food, beverages, pharmaceuticals, and chemical production.