The rennet and acid coagulation properties of reconstituted micellar casein concentrate prepared using cold or warm microfiltration (MF), at similar casein contents, were investigated, with low-heat skim milk powder (LHSMP) as a control. The MF retentates had higher casein content (as % of total protein) compared with LHSMP, and heat-induced whey protein-casein aggregates were only present in LHSMP. All MF retentates showed shorter rennet coagulation times and higher gel strengths than LHSMP, which may be linked to lower levels of whey protein (either native or denatured). At similar casein contents, longer rennet coagulation times were evident for cold MF retentates compared with warm MF retentates, as the ratio of κ-CN as a function of total increased with the depletion of β-CN. In terms of acid-induced coagulation, all MF retentates coagulated at a pH >5, higher than the gelation pH of LHSMP (4.7-4.9), which was confirmed by microscopic and textural analysis. An inflection point (increase, followed by a decrease) in the storage modulus value was seen during the acidification of warm MF retentates, but not cold MF retentates; this may be related to structural rearrangements of the gel initiated by release of colloidal calcium phosphate and compacting of the structure of warm MF retentate gels as pH decreased. Both warm and cold MF retentates exhibited shorter rennet coagulation times, stronger rennet-induced gels and higher acid-induced gelation pH compared with LHSMP, which might influence their use for the manufacture of cheese or yogurt with tailored functionalities.

Growing consumer demand for minimally processed, nutritionally intact dairy products has heightened the imperative to enhance raw milk safety while preserving its inherent composition. This review critically evaluates established nonthermal technologies, including ultraviolet-C (UV-C) irradiation, cold plasma (CP), high-pressure processing (HPP), pulsed electric field (PEF), and microfiltration (MF), alongside emerging innovations such as nanotechnology-enhanced filtration, artificial intelligence (AI)-driven optimization, and blockchain traceability. In contrast to conventional pasteurization, which often degrades thermolabile nutrients and modifies sensory attributes, these nonthermal approaches provide effective pathogen inactivation with superior quality retention. Recent developments in multi-hurdle strategies, integrating multiple nonthermal methods, demonstrate substantial promise for bolstering microbial safety and product uniformity. These achieve reductions of up to 6log10 in key pathogens like Escherichia coli and Listeria monocytogenes, while maintaining over 80% of vitamins and bioactive compounds (lactoferrin). The review synthesizes contemporary evidence on mechanisms, efficacy, and applicability, emphasizing impacts on vitamins, enzymes, and probiotic retention. It highlights synergistic systems (HPP+PEF, MF+UV-C) and their socioeconomic benefits, including premium market positioning and employment generation, as well as environmental advantages such as reduced energy consumption and lower waste. Moreover, it explores how these technologies address evolving consumer demands, sustainability objectives, and regulatory requirements. By offering a comprehensive, forward-looking analysis, this work illustrates the transformative potential of nonthermal innovations in the dairy sector. This review advances a convergent framework thatcritically integratesnonthermal processing with digital tools (AI, blockchain), aligning technological efficacy with supply chain transparency, regulatory pathways, and consumer confidence.

In biotechnological processes, value-added products such as 1,3-propanediol (1,3-PD) are obtained in multi-component mixtures consisting of by-products, nutrient medium, bacterial cells and residual substrate. For this reason, separation to obtain the main product with the use of various techniques is economically unprofitable. Contrary, membrane bioreactors (MBRs) ensure several benefits and may play a crucial role in reducing the operating costs. The main objective of this work was to evaluate the feasibility of producing 1,3-PD in an MBR equipped with capillary polypropylene (PP) membranes for the MF (microfiltration) process. This article provides an in-depth examination of: (i) the yield of batch, fed-batch and fermentation in an MBR, (ii) the fouling mechanism during MF of fermentation broths, and (iii) PP membrane stability. It was found that performing the fermentation in an MBR allowed for production of 1,3-PD with the highest maximum yield, in the range of 0.48 g/g (0.58 mol/mol) to 0.59 g/g (0.72 mol/mol). Moreover, it was demonstrated that the significant decline of the MF process was mainly caused by the formation of a cake layer on the membrane surface. Nevertheless, the efficiency of the process was stable and ensured the high quality of the permeate. In addition, membrane cleaning with the use of 1% NaOH solution allowed to remove most of the foulants from the membrane surface. Despite repeated cleaning procedures, the membranes used in this work maintained their performance and efficiency. Hence, it can be concluded that the capillary polypropylene membranes for the MF process can be successfully used in MBR technology intended for the production of 1,3-PD by glycerol fermentation.

Rising concentrations of organic carbon (OC), phosphorus, and nitrogen in liquid waste from urban, industrial, and agricultural sources pose persistent challenges for environmental protection and resource recovery. Despite extensive application of microfiltration (MF) and ultrafiltration (UF) in wastewater treatment, their role in selective organic carbon and nutrient fractionation remains insufficiently clear-cut and is often interpreted solely through nominal pore size. This review was guided by the hypothesis that the reported limitations of MF and UF for nutrient separation are not intrinsic to the technologies but arise from simplified interpretations of separation mechanisms. A unified analytical framework was developed by synthesizing recent studies, linking membrane surface charge, pore structure, solute speciation, fouling-induced secondary layers, and operating conditions to the observed separation behavior. The analysis shows that MF fractionates particulate OC and suspended solids, whereas UF extends separation to macromolecular OC and phosphorus mainly via indirect retention mechanisms. Dissolved nitrogen species largely permeate both membranes unless they are transformed into retainable forms. Performance differences between MF and UF are conditional and system-dependent, with enhanced selectivity emerging through process integration. MF and UF can thus be repositioned as strategic fractionation interfaces within integrated treatment systems supporting circular economy-oriented wastewater management.

Abstract The anaerobic microfiltration osmotic membrane bioreactors (AnMF-OMBRs) and up-flow anaerobic sludge blanket microfiltration osmotic membrane bioreactors (UASB MF-OMBRs) are innovative systems treating high-strength wastewater and recovering resources. The microfiltration (MF) and forward osmosis (FO) permeates of these systems contain varying amounts of nitrogen and phosphorus, which enrich soils and boost crop growth. Utilizing these permeates as fertilizers reduces dependency on chemical fertilizers, conserves natural resources, and valorizes wastewater. This study evaluates the application of MF and FO permeates of an AnMF-OMBR and a UASB MF-OMBR treating slaughterhouse wastewater as liquid fertilizer. Firstly, the permeates were blended with tap water to provide irrigation water quality, considering the national standards. Then, fertigation was applied using the blended MF (NH 4 + -N: 73–95 mg L −1 ; TP: up to 2.6 mg L −1 ) and FO (NH 4 + -N: 3.5–28 mg L −1 ; TP: < 0.5 mg L −1 ) permeates with tap water and their combination with nitrogen, phosphorus, and potassium fertilizers. After 22-day irrigation, analytical hierarchy process was applied to decide the best scenario for grass growth. Grass growth was assessed based on grass colour, soil and plant water retention capacity, coverage percentage, the number of fringes and shoots, and grass and root length. The results showed that the permeates of both bioreactors could be used as liquid fertilizer. Furthermore, in case of one-year full-scale operation of the systems, treating slaughterhouse wastewater, sufficient water was saved for the daily consumption of 240 people. The nutrient quantities in the MF permeates could fulfill 122%, 12%, and 46% of the nitrogen, phosphorus, and potassium needs for grass growth.

Abstract In recent years, consumer preferences have shifted towards healthier food choices, emphasizing quality and nutritional benefits. This study aims to utilize microfiltration to produce milk with a lower protein concentration, thereby improving its suitability for individuals with milk protein allergies. Microfiltration of fat-free UHT milk using ceramic membranes (Membralox – 5, 1.4, and 0.8 µm) demonstrated that a 0.8 µm pore size has efficient protein fractionation at high permeation rates, lowering the permeate protein concentration to <10 g L −1 (R Protein = 69.4%). Membranes with larger pore sizes (1.4 and 5 µm) exhibited only marginal protein selectivity, indicating their suitability primarily for cold-sterilization purposes. Enzymatic hydrolysis with papain was effective on the 0.8 µm permeate, yielding low-molecular-weight peptides and eliminating allergenic proteins based on molecular-weight reduction. Microfiltration (MF) can be employed as a pre-treatment to reduce protein content, facilitating enzymatic hydrolysis.

A primary target in the long-term microfiltration (MF) of fermentation broths is to ensure the high-quality permeate and stable system operation. This can be achieved by the choice of the most profitable membrane material and development of an effective membrane cleaning procedure. However, selecting the appropriate module configuration is also of key importance. This study assessed the suitability of capillary and spiral-wound modules for MF 1,3-propanediol (1,3-PD) fermentation broths, which were clarified only by 2 h of sedimentation. The obtained results demonstrated that the MF process allowed the removal of almost 100% of suspended solids from a feed. Consequently, the obtained high-quality permeate was characterized by the turbidity of 0.4–0.7 NTU. Fouling was mitigated by membranes’ washing with NaOH solution; hence, chemically resistant polytetrafluoroethylene (PTFE) and polypropylene (PP) membranes were installed in the modules. In order to determine dominant fouling mechanism, the Hermia model was applied. It has been shown that a decrease in the process performance was mainly caused by the formation of a cake layer on the membrane’s surface. A significant amount of the deposit also formed inside the mesh filling of the module channel, which excluded the use of spirally wound modules for the MF broth pretreated only by sedimentation. To avoid this phenomenon, the capillary PP membranes (diameter 1.8 mm) were applied. During long-term tests (over 700 h) membranes were periodically cleaned with the 1% NaOH solution, which removed most of the foulants. However, in this case, residual deposits formed by silicates remained on the membrane surface, requiring an additional membrane cleaning method. Finally, it has been noted that the PP membranes showed an excellent resistance to the frequent exposure to the foulants present in the fermentation broths and the alkaline agent.

Treatment of polymeric solid waste, such as used membranes, is vital for environmental sustainability. Cellulose-based membranes are widely utilized in the water industry due to their resistance to biodegradation. These non-biodegradable membranes can persist in landfills and aquatic environments for extended periods. Our study assessed the biodegradation potential of Trametes versicolor on a newly fabricated cellulose acetate (CA) membrane and a commercially produced membrane under various conditions, including oxidative stress. Additionally, we employed T. versicolor encapsulated in a small bioreactor platform (SBP) for media inoculation and biomass augmentation. Treatment of the commercially produced CA membrane within a timeframe of 30 days was unsuccessful. This was primarily attributed to the structural stability of the membrane over time and the limited ability of the culture to attach to the membrane surface. These results underscore the necessity of exploring alternative biopolymer cellulose-based materials for ultrafiltration (UF) and microfiltration (MF) membrane applications. The custom-made UF membrane, treated by ozonation as a pretreatment, emerged as an effective approach for enhancing biodegradation. Combining these factors, we expect to achieve over 27.75 ± 1.5% weight loss in membrane solids by 30 days of treatment. This study represents the first inquiry into the biodegradation capabilities of T. versicolor on CA-based membranes.

The current climate change crisis has significantly impacted the world, particularly through issues related to water scarcity and access, highlighting the urgent need for effective mitigation strategies. To address these challenges, a hybrid Microbial Fuel Cell (MFC)-Microfiltration (MF) system was developed for simultaneous wastewater treatment and energy generation. In this study, sugar factory effluent was treated using pre-constructed dual-chamber MFCs and monitored over a ten-day period. Following MFC operation, the effluent underwent MF treatment. The study also investigated the use of sargassum biomass as a flocculant in MFCs, with systems labelled as sugar factory effluent loaded with fresh sargassum (SFE-FS) and sugar factory effluent loaded with dry sargassum (SFE-DS). Among the MFCs tested, the SFE cell produced the highest power output (22.46 mW m⁻2) with a peak open-circuit voltage (OCV) of 0.797V. Wastewater analysis revealed that chemical oxygen demand (COD) removal for the SFE cell was 66% after MFC pretreatment and reached 100% following subsequent MF treatment. Similar trends were observed in the SFE-DS and SFE-FS cells. Across the three MFC-MF hybrid systems, the overall trends in COD, total suspended solids (TSS), and total dissolved solids (TDS) removal, along with increased dissolved oxygen (DO) and conductivity, followed the order: SFE > SFE-FS > SFE-DS. Flux values in the MF stage also followed this trend, increasing by 121%, 85%, and 60% for the SFE, SFE-FS, and SFE-DS systems, respectively.

In recent years, membrane separation technology has undergone continuous advancements. Microfiltration (MF) membranes, as an important type, are usually prepared by electrospinning—a simple and efficient method. This study reports the development of crosslinked polyvinyl alcohol/polyethylene glycol (cPVA/PEG) nanofiber membranes through a combination of electrospinning and chemical crosslinking, investigating the effects of different crosslinking concentrations on the membrane morphology, surface wettability, and tensile properties. Comprehensive characterization was carried out by using scanning electron microscopy (SEM), a Fourier-transform infrared spectrometer (FTIR), an X-ray diffractometer (XRD), a thermogravimetric (TG) analyzer, differential scanning calorimetry (DSC), a contact angle tester, a universal testing machine, etc. The results showed that at the crosslinking concentration of 15%, the cPVA/PEG fiber membrane achieved a breaking stress of 29.07 ± 2.60 MPa, a breaking strain of 77.60 ± 6.02%, and a porosity exceeding 43%. SEM, FTIR, XRD, TG, and DSC analyses collectively confirmed the occurrence of chemical crosslinking within the membrane structure. The cPVA/PEG-15 membrane exhibited no observable shrinkage or curling upon water contact, combined with excellent hydrophilicity and lipophilicity in the air. These properties indicate that the membrane can serve as a novel functional membrane substrate (e.g., as hydrophilic separation layers) and is expected to play an important role in fields such as seawater desalination and wastewater treatment, demonstrating significant application potential.

Composition-dependent pore structure and filtration performance of hydrogel-filled membranes.

This study aims to compare the carbon footprints associated with the fabrication of two types of alumina-based tubular ceramic membranes used in microfiltration (MF): a multichannel membrane produced by extrusion and dip-coating, and an asymmetric hollow fiber membrane fabricated via phase inversion. The multichannel process involves two sintering steps but uses no organic solvents, whereas the phase-inversion method simplifies production through single-step shaping and sintering but requires organic solvents that increase environmental burdens. Using a functional unit of 1 m2 effective membrane area, carbon emissions were quantified from raw material extraction to waste disposal. The results showed total emissions of 8.57 kg CO2-eq/m2 for the multichannel membrane and 10.67 kg CO2-eq/m2 for the hollow fiber membrane. Although the hollow fiber process consumed less energy, its extensive use of solvents, particularly NMP, led to significantly higher emissions. This study provides the first quantitative comparison of these two common ceramic membrane fabrication routes and underscores the importance of considering both energy use and solvent impacts when evaluating the environmental sustainability of membrane production. A sensitivity analysis further evaluated the influence of key parameters, including alumina emission factor, regional electricity carbon intensity, alumina recycling, and solvent substitution or NMP recycling. The analysis demonstrated that each factor could significantly influence the total carbon footprint and, under favorable conditions, narrow or even reverse the gap between the two fabrication routes. This study provides the first quantitative comparison of these two common ceramic membrane fabrication methods and highlights the importance of considering energy use, solvent impacts, and potential mitigation strategies when assessing the environmental sustainability of ceramic membrane production.

The dairy industry generates significant amounts of wastewater, including microfiltration (MF) retentate, a byproduct thickened with organic and inorganic pollutants. This study focuses on the treatment of two times concentrated MF retentate using a hybrid system based on biological treatment in a sequential batch reactor (SBR) and adsorption on activated carbon. The first stage involved cross-flow microfiltration using a 0.2 µm PVDF membrane at 0.5 bar, resulting in reductions of 99% in turbidity and 79% in chemical oxygen demand (COD), as well as a partial reduction in conductivity. The second stage involved 24-h biological treatment in a sequential batch reactor (SBR) with activated sludge (activated sludge index: 80 cm3/g, MLSS 2500 mg/dm3), resulting in further reductions in COD (62%) and TOC (30%), as well as the removal of 46% of total phosphorus (TP) and 35% of total nitrogen (TN). In the third stage, the decantate underwent adsorption in a column containing powdered activated carbon (PAC; 1 g; S_(BET) = 969 m2 g-1), reducing the concentrations of key indicators to the following levels: COD 84%, TOC 70%, TN 77%, TP 87% and suspended solids 97%. Total pollutant retention ranged from 24.6% to 97.0%. These results confirm that the MF-SBR-PAC system is an effective, compact solution that significantly reduces the load of organic and biogenic pollutants in MF retentates, paving the way for their reuse or safe discharge into the environment.

Metabolic products comparison in autotrophic and heterotrophic nitrogen removal: Insights into membrane fouling.

Membrane technology is primarily used for the separation and purification of biotechnological products, which contain proteins and enzymes. Membrane fouling during crossflow filtration remains a significant challenge. This study aims to initially validate crossflow filtration models, particularly related to pore-blocking mechanisms, through a comparative analysis with dead-end filtration models. One crossflow microfiltration (MF) and six consecutive ultrafiltration (UF) stages were implemented to concentrate laccase extracts from Pleurotus ostreatus 202 fungi. The complete pore-blocking mechanism significantly impacts the MF, UF 1000, UF 100 and UF 10 stages, with the highest related filtration constant (KbF) estimated at 12.60 × 10-4 (m-1). Although the intermediate pore-blocking mechanism appears across all filtration stages, UF 100 is the most affected, with an associated filtration constant (KiF) of 16.70 (m-1). This trend is supported by the highest purification factor (6.95) and the presence of 65, 62 and 56 kDa laccases in the retentate. Standard pore blocking occurs at the end of filtration, only in the MF and UF 1000 stages, with filtration constants (KsF) of 29.83 (s-0.5m-0.5) and 31.17 (s-0.5m-0.5), respectively. The absence of cake formation and the volume of permeate recovered indicate that neither membrane was exposed to exhaustive fouling that could not be reversed by backwashing.

Forward osmosis (FO) is a membrane technology that has attracted significant attention recently for water purification and desalination. However, widespread approval of FO technology faces challenges, including membrane performance issues, notably internal concentration polarization (ICP), and the trade-off between water permeability and salt rejection. This study focuses on developing high-performance FO membranes by coating a polyelectrolyte interlayer onto a microfiltration (MF) substrate, characterized by its large pore size, which mitigates ICP and enhances water flux. However, the use of an MF substrate without modification presents challenges in forming a defect-free polyamide (PA) active layer due to the large and irregular surface pores. To solve this issue, a polyelectrolyte thin layer is coated on the MF substrate surface to control the synthesis of the PA layer. The interlayer is deposited using a layer-by-layer (LBL) assembly technique with sodium lignosulfonate (SLS) and polydimethyldiallylammonium chloride (PDMAC) polymers. The LbL number can control the surface hydrophilicity and pore size. The results demonstrate that coating the interlayer significantly enhances the water flux of FO membranes from 10.1 LMH in the control TFC to 20.5 LMH in TFC-LbL.3 (with 3 LbL number). The interlayer provides a smooth and more uniform interface for the polymerization reaction, resulting in a thin and uniform PA layer. This leads to increased water flux while maintaining high salt rejection. This claim is verified by the higher rejection of heavy metal ions in TFC-LbL.3 (98.3% for Cr3+ and 97.8% for Pb2+) in comparison to the TFC (95.4% for Cr3+ and 94.2% for Pb2+) membrane. The LBL assembly technique provides a cost-effective and environmentally sustainable method for fabricating high-performance FO membranes.

This study explores the application and robustness of an adaptive optimal control (AOC) strategy to optimize the operation of membrane filtration systems. The proposed control is based on a constant flux model where fouling is primarily due to cake layer formation. The algorithm dynamically finds the optimal ratio between the filtration (F) and backwash (BW) time ratio in response to system disturbances, thereby adapting the operational state of the membrane in order to optimize its performance in terms of energy consumption. The strategy was successfully applied to both microfiltration (MF) and ultrafiltration (UF) systems and quantitatively demonstrated its effectiveness in reducing energy consumption and controlling fouling. It proved robust against model uncertainties and demonstrated real-time adaptability even under varying and realistic disturbance conditions. The implementation of this control strategy facilitated real-time adaptation of the filtration/backwash (F/BW) ratio in response to dynamic system disturbances. The result underlines that the control behavior is predominantly driven by fluctuations in mixed liquor suspended solids (MLSSs). Compared to conventional fixed-time modes, the AOC led to significant energy savings, ranging from 7% to 30%, and membrane lifespan extension, mainly through more efficient permeate pump usage.

Landfill leachate is a complex environmental concern due to its composition of organic pollutants, inorganic salts, ammonia, nitrogen, and heavy metals. Proper treatment is critical to prevent soil and groundwater contamination. This study conducts a meta-data analysis of advanced filtration techniques-reverse osmosis (RO), microfiltration (MF), ultrafiltration (UF), and nanofiltration (NF)-for landfill leachate extraction. A systematic review of studies published from 2020 to 2024 was performed which leads to the identification of eight relevant articles. The removal efficiencies of the various methods varied significantly, with RO showing the highest performance at 99%, followed by NF at 89.8%, UF at 61%, and MF at 25%. Despite the high efficacy of RO, limitations such as high energy consumption, membrane fouling, and waste concentrate production were noted. NF and UF also demonstrated good performance but faced challenges with specific pollutants and operational efficiency. MF, while less effective, could be useful in pre-treatment stages. The study suggests that further advancements including the integration of multiple treatment technologies are necessary to enhance performance and reduce environmental impacts. Future research should address the limitations of current methods to ensure more sustainable landfill leachate management.

Membrane technology has been increasingly applied in water purification to address global water scarcity. However, commercial membranes inevitably reach the end-of-life (EoL) after long-term operation, which constrains the sustainability of membrane technology. Herein, we demonstrated the feasibility of upcycling real EoL poly(vinylidene fluoride) (PVDF) microfiltration (MF) membranes into reverse osmosis (RO) membranes with higher separation precision via the interfacial polymerization (IP) reaction. We highlighted that the EoL MF membrane, with a fouling-induced narrowed pore size and relatively hydrophobic properties, is preferred for upcycling. The resultant upcycled RO membrane exhibited a satisfactory NaCl rejection (98.6 ± 0.4%) with favorable water permeance (2.3 ± 0.7 L m-2 h-1 bar-1), comparable to the performance of commercial RO membranes. Real wastewater treatment evaluations confirmed the membrane stability and permeate safety. Life-cycle assessment and techno-economic analysis showed that this upcycling process promises environmental and economic benefits, potentially reducing CO2-eq emissions by 18.6% and costs by 76.5%-92.2% compared with the conventional membrane approach. This proof-of-concept study paves the way for creating a closed eco-loop of membrane recycling for sustainable water purification.

Abstract Microplastics (MPs) are increasingly pervasive in global water bodies, raising environmental and health concerns due to their small size and potential for bioaccumulation. Once inside the body, MPs are difficult to degrade, leading to potential health risks. Ongoing research seeks effective method mitigate MP contamination, with membrane technology emerging as a promising approach to remove MP pollutant from water. This research focuses on the ability of membranes to remove polypropylene (PP) MP particles. Distilled water samples containing PP plastic particles were prepared to assess the effectiveness and mechanism of PP removal through membrane technology. Microfiltration (MF) and ultrafiltration (UF) membranes were operated were operated under specific pressure criteria for each type. The MP removal efficiency was calculated based on the rejection coefficient of each membrane. The MF membrane showed a rejection coefficient up to 99%, while the UF membrane gained a perfect rejection rate of 100%. This study confirms that membrane technology is a viable solution for managing MP pollution in aquatic environment. Membrane technology has been proven to be a potential solution for managing MP pollution in aquatic environment.