Reduce Membrane Fouling Research Articles

Optimization of Forward Osmotic Dewatering on Resource Utilization of Microalgae: A Review

Microalgae have attracted wide attention due to their extensive application potential. Dewatering is a necessary work for the application of microalgae, especially in biofuel production, where forward osmosis (FO) research is relatively advanced but still faces technical bottlenecks hindering large-scale commercialization. Based on the current research in recent years, the research progress in the causes and control of membrane fouling, the development of membrane materials and optimization of membrane structure, and the energy saving and efficiency of the process are reviewed in this paper. We found that different species of algae have direct effects on membrane fouling. Chlorella vulgaris has a low membrane fouling trend, but the mechanisms of fouling need further investigation. The material development and structure optimization of membranes are the main research methods to reduce membrane fouling, but there are still some defects, such as complicated preparation and low water flux, which are difficult to apply on a large scale. The research progress of reducing costs by using seawater, urine, fertilizer, etc. as new draw solutions (DS) is reviewed. At present, many aspects of FO microalgae dewatering technology are still not well understood, and future research should focus on scaling up the existing technologies.

A novel gravity-driven fixed-bed ceramic membrane filtration (GDFBCM) with critical PAC-MnOx-ceramsite filters for simultaneously removing hazardous manganese and ammonia from groundwater.

Groundwater is widely threatened by hazardous manganese and ammonia. In present study, a novel gravity-driven fixed-bed ceramic membrane filtration (GDFBCM) with critical PAC-MnOx-ceramsite filters was built to address these issues. Static ceramsite filters in GDCM significantly increased membrane flux from 11 L/m2·h to 18 L/m2·h on the 50th day of filtration. Their synergistic effects with aerated fluidization further reduced membrane fouling by 29 %. Ammonia removal was improved from 62 % to 78 % by ceramsite filters after accelerating nitrification and denitrification by stimulating Nitrospira and Nitrosomonas. Metabolite secretion, ATP level, bacteria abundance and microorganism community analysis evidenced that ceramsite filters acted as immobilization carriers to stimulate Mn-oxidizing bacteria (e.g. Pseudomonas and Hyphomicrobium) for greater biological oxidation of dissolved manganese. According to FTIR, XRD, XPS spectra and SEM-EDS mapping, the facilitated formation of two-dimensional sheet-like birnessite on ceramsite filters established a virtuous cycle for continuous manganese removal. These processes further benefited from the increased hydraulic retention time by denser membranes. The excellent resistance to suddenly increasing pollution loading confirmed the outstanding applicability of GDFBCM. Energy consumption analysis also indicated that GDFBCM was an energy-saving system for groundwater treatment with the specific energy consumption of less than 4 × 10-3 kWh/m3.

Highly selective copper recovery from industrial wastewater via electric field-enhanced ultrafiltration assisted with a picolyl-modified polyelectrolyte.

Copper-containing industrial wastewater, characterized by strong acidity, high ionic strength, and various competing metals, presents significant challenges for Cu(II) recovery. To address these issues, an electric field-enhanced ultrafiltration process was developed, assisted with a functional polyelectrolyte with high selectivity for Cu(II). The polyelectrolyte, termed PPEI, was synthesized by grafting picolyl groups onto polyethyleneimine (PEI), enhancing its affinity for Cu(II). The captured Cu(II) was subsequently recovered through electrolysis, demonstrating a sustainable approach for both Cu recovery and PPEI recycling. The synthesis and stability of PPEI were confirmed through infrared spectroscopy, particle size analysis, and dialysis validation, ensuring its reliability in practical applications. The incorporation of picolyl groups onto PPEI enhances its selectivity for Cu(II) via coordination with two amines and four pyridyl groups per copper ion. Under acidic conditions, the maximum loading ratio of copper to PPEI is 1:4 with loading capacity of 119.4 mg/g, which increases to 1.5:4 (i.e., 179.1 mg/g) under neutral to alkaline conditions due to the deprotonation of excess amines. PPEI effectively removes Cu(II) from solutions under various harsh conditions at the loading ratio of 4, maintaining 92-98 % removal efficiency in the presence of high salt concentrations (up to 1 M NaCl) and pH as low as 1, and approximately 85 % removal in solutions with competing metal ions at concentrations up to 50 times higher than Cu(II). Scanning electron microscopy and membrane flux changes indicated that the application of a positive electric field significantly reduces membrane fouling and enhances Cu(II) selectivity. The application of a +0.2 V voltage to the membrane side reduced the flux decline rate by 58 %, significantly improving membrane performance while maintaining a Cu(II) removal efficiency of over 95 %. Electrolysis optimized at a current density of ≤0.004 A/cm2 achieved an 80 % copper recovery while allowing PPEI to be released for recycling. Tests conducted using two types of real industrial wastewater demonstrated a copper removal rate of ∼95 %, with a recovery rate of ∼80 %. This study provides a novel and highly selective approach for the efficient recovery of valuable metals from industrial wastewaters.

Effects of a 3D-Printed Turbulence Promoter on Membrane Fouling During the Ultrafiltration of Dairy Wastewater

In this study, the integration of a 3D printed turbulence promoter into a stirred membrane separation cell during dairy wastewater ultrafiltration was investigated. Its effects, along with the effects of stirring, on the permeate flux and membrane fouling were examined. The experiments were carried out at different transmembrane pressures (0.1, 0.2, and 0.3 MPa) and stirring speeds (RPM: 100–400 min−1), both with and without the application of the turbulence promoter. Various parameters were employed to characterize the membrane performance, such as the permeate flux, the flux decline ratio, and the fouling coefficient. To further investigate the membrane fouling mechanisms, mathematical models were used: the resistance-in-series model, the Makardij model, and the Hermia model. With the resistance-in-series model, we examined whether the membrane fouling was reversible (the deposit could be easily removed by washing operations) or irreversible (irreversible fouling) for each measurement, and with the Makardij model, we investigated whether the rate constant of the fouling or the rate constant of the deposit removal was the most important. In the case of the Hermia model, changes in the cake filtration rate constant were monitored. The results indicate that the combination of the 3D printed turbulence promoter and the stirring speed could effectively reduce membrane fouling during dairy wastewater ultrafiltration.

Improving ultrafiltration efficiency of acidified skim milk using bipolar membrane electrodialysis: Impact on protein concentrate composition, process performance, and fouling

The efficiency of ultrafiltration (UF) of acidified skim milk (SM) is impaired by protein aggregation and mineral scaling. The aim of this study is to assess the potential of acidification by electrodialysis with bipolar membranes (EDBM), in comparison with citric acid (CA), prior to the UF process on filtration performance, fouling and composition of the protein concentrates. Electro-acidification, facilitated by a water-splitting reaction, decreased the pH of milk to ∼ 5.7 and caused partial demineralization (∼21.9 % ash removal), which increased protein concentration and reduced UF fouling. This resulted in a ∼ 34.7 % increase in average permeate flux and ∼ 9.5 % more efficient removal of calcium from the UF retentates compared to CA. The final ash content of the produced protein concentrates showed that the EDBM acidification resulted in an ash content of 5.76 ± 0.23 % on a dry basis, while the citric acid method resulted in an ash content of 6.63 ± 0.27 %, showing a reduction of ∼ 13.1 %. Additionally, electro-chemical and spectroscopic methods were employed to evaluate the ion-exchange membranes (IEMs). Minor changes were observed in the specific resistivity and permselectivity of the cation-exchange membranes (CMs), indicating the formation of fouling and inorganic scaling precipitates on the membrane surface due to the process. The FTIR analysis of both CMs and bipolar membranes (BMs) showed sorption of proteins on the surface. The FTIR and atomic force microscopy (AFM) results of UF membranes confirmed that acidification using CA led to increased fouling and reduced permeate flux, attributed to the aggregation of proteins and lipid residues compared to the EDBM acidification method. This study provides valuable insights into improving and enhancing UF performance while significantly reducing membrane fouling during the filtration of partially acidified dairy streams, by employing chemical-free green technologies.

Upgrading the eastern wastewater treatment plant effluent quality in Egypt for reuse by means of in-line coagulation followed by ultrafiltration

ABSTRACT Providing clean water to Egyptian citizens is one target of the 2030 sustainable development goals. Ultrafiltration (UF) has been investigated as an advanced treatment of the largest treatment plant in Alexandria. Although UF membranes have been widely used to treat secondary effluent, fouling remains a major challenge. The effects of green and conventional coagulants on controlling ultrafiltration fouling were examined. Two different dosages of each coagulant and a combination of ferric chloride and sodium ferrate were studied in a bench-scale setup that was built and operated under identical circumstances. The results showed that the combined ferrate and ferric chloride pretreatment had the highest performance in terms of the removal of organics and turbidity as well as the reduction of membrane fouling. Fouling can be managed in terms of the normalized flux drop with only 0.5 mg/L of ferrate, which performs similarly to 2.5 mg/L of ferric chloride. The higher the dosage of alum used, the lesser the fouling control observed. The green coagulant, when used as an in-line coagulant aid/oxidant with ferric chloride at very low doses, has a favorable potential to reduce membrane fouling and improve permeated wastewater quality, making it suitable for Grade A for reuse purposes.

Yolk-shell structured Co3O4 catalyst modified ceramic membrane synergistically improved wastewater purification and membrane fouling mitigation

Wastewater increases and water shortage crises have forced the rapid innovation of water reuse technologies. Ceramic membrane process (CM), as one of the key technologies for wastewater reclamation, can effectively light the current difficulties. However, membrane fouling and low retention rate are critical bottles that hinder its further application. Herein, we proposed yolk-shell Co3O4 spheres modified CM (CoHM-CM) activating peroxymonosulfate (PMS) to improve membrane filtration performance. The results showed that the synergistic effect of size exclusion of CM and spatial confinement of CoHM enhanced the collision between organic pollutants and active sites. CoHM-CM/PMS (30 mg CoHM loading combined with 0.5 mM PMS dosage) degraded 100 % of 10 mg/L phenol, bisphenol F and sulfamethoxazole, and 91.29 % of 5 mg/L carbamazepine at an instant of membrane filtration. This process efficiently removed secondary effluent organic matter and reduced membrane fouling resistance by more than 70 % in actual wastewater environments. Besides, the yolk-shell catalytic membrane had strong Co2+ regeneration capacity and chemical stability. It coupled PMS-generated sulfate radicals and singlet oxygen play a core role in increasing the membrane interface energy barrier and releasing the developing tendency of membrane pore blocking to severe cake layer filtration fouling. The results provided a new opportunity for wastewater remediation based on the yolk-shell modified membrane technology.

Surface- and substrate-coated catalytic membrane for mitigating interference of water matrix species in intensified micropollutant confinement oxidation

The integration of advanced oxidation processes (AOPs) with membrane technology offers benefits for catalyst recovery and reducing membrane fouling. However, the application of the hybrid process could be hampered by the background species in water matrix. This study addresses this challenge by developing catalytic ceramic membranes (CCMs) with dual mechanisms to intensify acetaminophen (ACT) removal in water. The CCMs effectively activated peroxymonosulfate (PMS), achieving ACT degradation of 85 % and 93 % in real water matrices (reverse osmosis retentate and settled water, respectively) and 99 % in MQ water. The CCMs demonstrated consistent performance across multiple operational cycles, even in the presence of humic acid (HA) (96 % ACT reduction). The CCM design features Co3O4 catalytic layer on CCM surface, facilitating surface oxidation, reducing fouling, and TiO2 intermediate rejection layers serving as barrier for bulk organic pollutants, achieving 50 % HA removal through rejection and 70 % with 1.5 mM PMS. This design facilitates catalytic degradation at the membrane surface, allowing retention and degradation of bulk organic pollutants and intermediates, while ACT permeates into CCM substrate. The surface oxidation and rejection enhanced confinement oxidation within the Co3O4-coated macropores, minimizing interference from background species. LC-QTOF analysis identified multiple degradation pathways, including hydroxylation, acetyl-amino group cleavage, side chain oxidation and benzene ring cleavage, with intermediates showing reduced toxicity. Reactive oxygen species involved in the system were identified and PMS activation mechanism was proposed. This research highlights the potential of the hybrid process, enhancing micropollutant removal by mitigating interference from background species, providing practical implications in water treatment applications.

Dual-layer coated photocatalytic membranes for surface water treatment: Insight of membrane fouling restriction

The combination of carbon-based material adsorption and photocatalytic oxidation is a crucial approach to eliminate natural organic substances and mitigate membrane fouling induced by them. In this investigation, Bi2O3-TiO2 (BT) was incorporated with three varieties of carbon-based substances (such as powdered activated carbon (PAC), ordered mesoporous carbon CMK-3 (OMCs), and carbon nanotubes (CNTs)) and employed as a dual-layer coating on the surface of the ultrafiltration membrane to reduce membrane fouling induced by natural organics during the treatment of actual water bodies. Under light conditions, the BT/CMK-3 coating outperforms BT/PAC and BT/CNTs coatings in reducing membrane fouling, with a flux recovery rate of up to 80.4 % and an irreversible fouling rate as low as 19.5 %, while also improving the removal rates of UV254 and DOC to 55.2 % and 77.9 %, respectively. Based on the analyses of three-dimensional fluorescence PARAFAC and liquid chromatography, the BT/CMK-3 coating efficiently removes humic substances and protein-like compounds via adsorption and photocatalytic oxidation, achieving a 24.1 % removal rate of humic acid and a 93.7 % removal rate of low molecular weight neutral substances. Under the synergy of CMK-3 adsorption and BT photocatalytic oxidation, reactive oxygen species effectively degraded and transformed the membrane foulants enriched by CMK-3, reducing and increasing the Zeta potential and free energy on the membrane surface to −4.2 mV and 15.1mJ/m2, respectively. The interaction force between the foulant and the membrane changed into a repulsive force, and the fouling mechanism changed from complete blockage to intermediate blockage, thereby shortening the transition time. This advancement provides significant promise for the development and broader application of photocatalytic membrane filtration technology.

Light-responsive zwitterionic membrane surface modification for antifouling and antibacterial application

Light-responsive surface modifications offer a promising solution for reducing membrane fouling by enabling remote, contactless cleaning without altering the chemical environment. While traditional methods make membranes hydrophilic to resist fouling, biofouling remains difficult to remove and often requires harsh bactericidal treatments. With the rise of antimicrobial resistance (AMR), there is a pressing need for alternative, non-bactericidal strategies to control biofilm growth. In this study, we developed an efficient approach by coating commercial ultrafiltration polyethersulfone (PES) membranes with a copolymer of light-responsive azobenzene (AZO) and zwitterionic sulfobetaine methacrylate (SBMA). The photochemical conversion efficiency and photokinetic parameters of the copolymer, due to light-induced trans–cis-trans conversion, were systematically determined. During filtration, the modified membranes showed excellent resistance to reversible fouling with bovine serum albumin (BSA). The fouled membrane became reusable after near-complete removal of irreversible fouling, including bacteria (Pseudomonas aeruginosa), by activating the AZO units with UV–vis light, providing an effective strategy for fouling control.

Study on an Integrated Water Treatment System by Simultaneously Coupling Granular Activated Carbon (GAC) and Powdered Carbon with Ultrafiltration

The process of using powdered activated carbon (PAC) in conjunction with ultrafiltration (UF) has been widely adopted for the treatment of various types of water and wastewater. However, during the application of this integrated PAC-UF process, PAC tends to adhere significantly to the surface of the UF membrane, which exacerbates membrane fouling. To tackle this issue, this study proposed an innovative water treatment approach that simultaneously integrated granular activated carbon (GAC) and PAC/biochar with UF. In this setup, PAC/biochar was intended to enhance water quality, while the fluidized GAC particles were aimed at reducing membrane fouling and the deposition of PAC/biochar on the membrane surface. We systematically analyzed the operational performance of the integrated systems concerning fouling formation, PAC/biochar attachment, effluent quality, and foulant components. The results indicate that both PAC and biochar effectively improved effluent quality in terms of chemical oxygen demand (COD) and hardness, although they significantly deposited on the membrane surface during operation. Notably, PAC was more prone to attach to the membrane than biochar, and the fouling in biochar-UF systems was primarily attributed to the attachment of organic foulants rather than biochar itself. By combining with GAC, up to 46.01% of membrane fouling and 96.11% of PAC/biochar attachment were mitigated due to the strong mechanical action of the fluidized GAC particles. Importantly, the inclusion of fluidized GAC did not significantly affect effluent quality. Consequently, the GAC-PAC/biochar systems proposed in this study demonstrated dual benefits of improving effluent quality and ensuring stable operation, thereby providing a viable solution for efficient and sustainable water treatment.

Enhancing nutrient water recovery: An integrated electrodialysis – Forward osmosis approach for reduced energy consumption and membrane fouling

The concept of combining electrodialysis (ED) and forward osmosis (FO) was previously introduced and proven effective in recovering nutrients and clean water from anaerobic effluents to produce safe liquid fertilizer. In this study, a novel and improved EDFO configuration (iEDFO) was proposed by merging the ED diluate with the FO feed solution and the ED concentrate with the FO draw solution, thus overcoming concentration limitations and fouling challenges inherent in traditional ED processes. Experimental results demonstrated significant improvements in performance, including up to 54 % and 43 % reductions in operation time and 21 % and 25 % energy savings for synthetic and real liquid digestate, respectively. These enhancements were attributed to altered ionic composition within the ED process, leading to higher, more stable current density and reduced ion back diffusion. Unlike conventional ED-only systems, the iEDFO configuration enabled continuous operation without requiring larger membrane areas or variable operational conditions. Additionally, the iEDFO configuration benefited from (1) reduced membrane fouling, and (2) decreased transport of organic contaminants across the anion exchange membranes (AEMs) into the ED concentrate product. Overall, the iEDFO system provides significant advantages in efficiency, energy savings, and operational stability, making it a highly effective and sustainable solution for resource recovery from liquid waste.

Biochar-driven fouling mitigation in sustainable microalgal-bacterial membrane bioreactors

Microalgal-bacterial membrane bioreactor (MB-MBR) have emerged as a crucial technology for sustainable wastewater treatment. However, membrane fouling caused by free microalgae remains a major obstacle to their cost-effective operation. This study investigated the impact of biochar addition on membrane fouling in MB-MBR. The findings indicated that biochar significantly reduced membrane fouling, primarily due to the enlargement of floc size and the reduction of soluble microbial products (SMP). Detailed analyses suggested that biochar's adsorptive properties and its effect on decreasing the abundance of algae and bacteria species, such as Proteobacteria and Leptolyngbya, which promote fouling, are key factors. This alteration enhanced specific amino acid metabolic pathways, thereby reducing SMP production and fouling potential. Consequently, adhesion interaction energy of the flocs and membrane fouling were both diminished. This study demonstrated that biochar addition is an effective strategy for mitigating membrane fouling in MB-MBR systems, providing a theoretical foundation for their stable and sustainable operation.

Direct Membrane Filtration (DMF) of municipal wastewater – A study on the prevention and remediation of fouling

Direct membrane filtration (DMF) has gained a lot of attention in recent years because of its potential to treat low-strength and low temperature wastewater, where biological based treatments are inefficient. However, fouling is a major concern which keeps this technique from being more widely used. The main aim of this study was to investigate membrane fouling, its mitigation approaches and the organic/nutrient retention during DMF of municipal wastewater by adjusting operational parameters and pretreating the sewage. In a laboratory-scale setup employing crossflow to mitigate fouling, both ultrafiltration and microfiltration membranes were utilized. Physicochemical pre-treatment of sewage with polyaluminum chloride and polyamide significantly inhibited membrane fouling and improved organics/nutrient retention. Subsequent experiments with physiochemically pre-treated sewage, using microfiltration and ultrafiltration separately, revealed that (i) an increase in crossflow velocity from 1 to 2 m s −1 improved filtration performance by reducing irreversible fouling, (ii) elevating transmembrane pressure from 0.18 to 0.4 bar increased both reversible and irreversible fouling, and (iii) periodic relaxation increased the extent of irreversible fouling, contributing to higher overall fouling in ultrafiltration. When employing DMF for sewage concentration, ultrafiltration demonstrated superior filtration performance and organics retention compared to microfiltration. Furthermore, through pre-precipitation and microsieving (100 μm) followed by DMF with ultrafiltration membranes, a remarkable removal efficiency of 92 % for chemical oxygen demand (COD), 98 % for total phosphorus (TP), and 100 % for total suspended solids (TSS) was achieved. By cleaning the fouled membranes using an alkaline cleaning solution (Ultrasil-10) at 50 °C, combined with a crossflow of 1 m s−1, the permeability was completely restored. Overall, this study demonstrates that by optimizing operational settings and cleaning conditions, a sustainable DMF process for wastewater treatment with controlled membrane fouling and improved resource recovery can potentially be developed for upscaling. Short abstractThis study investigated the effectiveness of direct membrane filtration for municipal wastewater treatment. It was found that physicochemical pre-treatment with polyaluminum chloride and polyamide significantly reduced membrane fouling and improved nutrient retention. Ultrafiltration membranes demonstrated superior performance and nutrient retention compared to microfiltration membranes. By optimizing operational parameters and cleaning conditions, a sustainable direct membrane filtration process with controlled fouling and improved resource recovery can be developed for wastewater treatment.

Membrane fouling characteristics and mechanisms in coagulation-ultrafiltration process for treating microplastic-containing water

Microplastics (MPs) are recognized as a significant challenge to water treatment processes due to their ability to adsorb or accumulate alginate foulants, impacting the coagulation-ultrafiltration (CUF) process. In this study, the mechanisms of membrane fouling caused by MPs under varying dosages of polymeric aluminum chloride (PAC) coagulant in the CUF process were investigated. It was revealed that MPs contribute to membrane fouling, which initially intensifies and then alleviates as coagulant concentration increases, with a turning point at 0.05 mM PAC dosage. The most significant alleviation of membrane fouling was observed at 0.2 mM PAC dosage. An in-depth analysis of interfacial interaction energy changes during filtration was conducted using the extended Derjaguin-Landau-Verwey-Overbeek (XDLVO) theory, demonstrating how MPs alter the interaction forces between foulants and the membrane surface, leading to either the exacerbation or mitigation of fouling. Additionally, it was shown that at optimal coagulant concentrations, the presence of MPs promotes the formation of a loose and porous cake layer, disrupting the original structure and creating a more open block structure, thereby alleviating membrane fouling. These findings provide valuable insights for optimizing the CUF process in microplastic-containing water treatment, presenting a novel approach to enhancing efficiency and reducing membrane fouling.

Enhanced Pollutant Removal and Antifouling in an Aerobic Ceramic Membrane Bioreactor with Bentonite for Pharmaceutical Wastewater Treatment.

This study examined the impact of adding bentonite clay (concentration of 1.5 to 10 g/L) to a pilot-scale aerobic ceramic membrane bioreactor (AeCMBR) for treating pharmaceutical wastewater (PhWW). The hydraulic retention time (HRT) was maintained at 24 h; the dissolved oxygen was between 2 mg/L (on) and 4 mg/L (off) throughout operation. Organic and nitrogen pollution removal rates and heavy metal (Cu, Ni, Pb, Zn) reduction rates were assessed. The chemical oxygen demand (COD) removal efficiency exceeded 82%. Adsorption improved ammonia (NH4+) removal to 78%; the addition of 5 g of bentonite resulted in a 38% improvement compared with the process without bentonite. The average nitrate concentration decreased from 169.69 mg/L to 43.72 mg/L. The average removal efficiencies for Cu, Ni, Pb and Zn were 86%, 68.52%, 46.90% and 56.76%, respectively. Bentonite at 5 g/L significantly reduced membrane fouling. The cost-benefit analysis enabled us to predict that the process will meet the multiple objectives of durability, treatment performance and economic viability. The combination of an AeCMBR and bentonite adsorption has proven to be a valuable solution for treating highly polluted wastewater.

Coupling Low-Frequency Ultrasound to a Crossflow Microfiltration Pilot: Effect of Ultrasonic Pulse Application on Sono-Microfiltration of Jackfruit Juice.

To reduce membrane fouling during the processing of highly pulpy fruit juices into clarified beverages, a crossflow Sono-Microfiltration (SMF) system was employed, strategically equipped with an ultrasonic probe for the direct application of low-frequency ultrasound (LFUS) to the juice just before the entrance to the ceramic membrane. Operating conditions were standardized, and the application of LFUS pulses in both corrective and preventive modes was investigated. The effect of SMF on the physicochemical properties and the total soluble phenol (TSP) content of the clarified juice was also evaluated. The distance of ultrasonic energy irradiation guided the selection of the LFUS probe. Amplitude conditions and ultrasonic pulses were more effective in the preventive mode and did not cause membrane damage, reducing the operation time of jackfruit juice by up to 50% and increasing permeability by up to 81%. The SMF did not alter the physicochemical parameters of the clarified juice, and the measured LFUS energy ranges did not affect the TSP concentration during the process. This study is the first to apply LFUS directly to the feed stream in a pilot-scale crossflow microfiltration system to reduce the fouling of ceramic membranes and maintain bioactive compounds in jackfruit juice.

Mitigation of Membrane Fouling in Membrane Bioreactors Using Granular and Powdered Activated Carbon: An Experimental Study

This experimental study explores the mitigation of membrane fouling in membrane bioreactors (MBRs) through the combined use of granular activated carbon (GAC) and powdered activated carbon (PAC). The research assesses the impact of these materials on the fouling resistance, critical flux, and permeate quality using various mixed liquor suspended solids concentrations and carbon dosages. The results indicate that the GAC-PAC combination significantly reduces the total filtration resistance, particularly the cake layer resistance, by 11.7% to 13.6% compared to setups without activated carbon or with the individual carbon types. The study also reveals that this combination decreased the fouling rate by 15% to 24% at critical flux steps, demonstrating substantial improvements in fouling mitigation and operational efficiency. Furthermore, the GAC-PAC combination, which produces an adsorption process, enhances the permeate quality, achieving the near-complete removal of organic matter, total nitrogen, and turbidity, with total phosphorus removal reaching 99%. These findings demonstrate that the combined use of GAC and PAC not only reduces membrane fouling but also improves the overall MBR performance, making it a viable strategy for enhancing the efficiency of wastewater treatment processes.

A high-flux, photocatalytic wood-derived filter for high-efficiency water purification

Wastewater purification has evolved into a global problem in the face of increasing scarcity of freshwater resources. Photocatalysis technology possesses prominent advantages in treating pollutants in water because of its low cost and mild reaction conditions, which provides an effective way to treat multiple pollutants and reduce membrane fouling. Herein, we combine photocatalysis technology with filtration technology via in situ reduction Bi0 with Bi2SiO5 strategy incorporating a carbonized wood filter to synthesize carbon/Bi2SiO5@Bi bi-functional composite. Thus, simultaneous filtration and photocatalytic degradation of Rhodamine B and tetracycline were achieved. After filtrating for 30 min, the degradation rate of RhB and TC were 94.23 % and 81.39 %, respectively. Especially, the flux of RhB and TC were up to 2162.16 L m−2 h−1 and 1811.32 L m−2 h−1. In addition, the composite filter also has good recyclability and reusability, after 5 cycles, the degradation efficiency of RhB remains at 91 %. This study utilized photocatalytic technology combined with membrane filtration technology to successfully solve the contradiction between catalytic efficiency and water flux, which realized rapid and dynamic removal of organic pollutants from water. Besides, the use of carbonized wood-based materials provides a potential biomass technology for the preparation of bifunctional photocatalytic filters.

Process optimization and characteristics of enzymatically cross-linked and ultrafiltrated whey

Whey, a byproduct of cheese production, is valued for its high-quality proteins. Ultrafiltration concentrates these proteins but faces challenges such as membrane fouling. This study investigates the use of transglutaminase to improve ultrafiltration efficiency by reducing fouling and optimizing protein recovery. Whey was divided into samples of whey in natura (WIN) and whey partially demineralized (WPD). Both were treated with different concentrations of transglutaminase (0, 0.5, 1.5, and 2.5% relative to protein mass) and ultrafiltered using polyethersulfone membranes at 4 bar. Effectiveness was evaluated by permeate flux and protein concentration, as well as physicochemical and structural characterizations such as FTIR, TGA, and molecular weight analysis. Transglutaminase reduced membrane fouling, increasing permeate flux. The 2.5% enzyme concentration was most efficient for WIN, while 1.5% was ideal for WPD. Enzymatic treatment increased protein concentration and thermal stability of the concentrates. FTIR analysis indicated the formation of cross-links between proteins. Molecular weight analysis revealed larger and more stable protein aggregates, improving ultrafiltration performance. This study suggests that transglutaminase is promising for optimizing whey ultrafiltration, improving protein recovery and process efficiency, with potential large-scale application in the food industry.