Search Results (367)

In this study, core–shell molecularly imprinted polymers (CS-MIP) were utilized for the detection of the herbicide S-metolachlor in surface water samples, collected from a river and pond that are in the proximity of cornfields. The study revealed that no traces of herbicide were detected in the samples that were analyzed. The collected water samples were treated with membrane filtration—microfiltration and ultrafiltration. The adsorption isotherms were fitted using the Langmuir, Freundlich, Dubinin–Radushkevich, and Scatchard models. This indicated that the Scatchard model is the most appropriate for CS-MIP. The data obtained from the kinetic study were analyzed using the pseudo-first-order and pseudo-second-order models, as well as Fick’s second law. For CS-MIP, the most suitable model was determined to be the particle diffusion model, while for core–shell non-imprinted polymers (CS-NIP), the film diffusion model was identified as the limiting step. A method for the desorption of S-metolachlor from the pH-sensitive sorbent bed has been developed, thereby enabling the material to be reused. The optimum eluent from the multicomponent solution was determined to be a 30% aqueous ethanol solution with a pH of approximately 9. This solution effectively removed the majority of contaminants, with the exception of S-metolachlor, which was retained within polymer pores. Full article

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. Full article

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. Full article

The coconut water market continues to expand, but industrial supply is constrained by the high perishability of fresh coconut water and the need for stabilization routes that preserve quality. This study optimized crossflow microfiltration of coconut water using a silicon carbide (SiC) ceramic membrane, high permeability, chemical/thermal robustness, and cleanability, and assessed the techno-economic feasibility of a green coconut biorefinery producing microfiltered coconut water and coconut pulp. Pressure and temperature were modeled and optimized using a face-centered design (FCD) and artificial neural networks coupled with a genetic algorithm (ANN–GA), considering permeate flux and fouling index (p < 0.05). Both approaches converged to the same operating point, and experimental validation at 75 kPa and 30 °C achieved 605.32 ± 15.34 L h⁻¹ m⁻² and 82.79 ± 1.35% at VRR = 1. Sample-level fit statistics favored ANN (higher R² and lower sample-level errors), whereas condition-wise grouped cross-validation (leave-one-condition-out) indicated higher predictivity and lower RMSE_CV for the quadratic FCD/RSM models across experimental conditions, highlighting response-dependent generalization within the investigated domain. Fouling analysis indicated concentration polarization as the main resistance contribution and a flux-decline behavior best described by the intermediate blocking mechanism. A SuperPro Designer^® simulation over a 20-year project life indicated economic feasibility under baseline assumptions (Internal rate of return—IRR = 23.80%, Net present value—NPV = US$733,761, payback = 2.96 years), with profitability remaining attractive under ±10% selling-price variation. Overall, the process optimization and modeling outcomes align with the economic case, reinforcing the potential of this biorefinery concept for industrial deployment. Full article

Important advancements in the development of novel materials and designs have led to the creation of advanced mineral membranes with high packing densities and enhanced competitiveness in relation to polymeric and classic mineral membranes. Olive juice represents an underutilised source of phenolic and secoiridoid antioxidants, in which industrial valorisation is hindered by some technical limitations, particularly the effective removal of suspended solids during processing. The efficiency of two recrystallized silicon carbide-based microfiltration membranes with an equivalent industrial filtration packing density of 782 m²/m³ was evaluated. One of them had nominal pore sizes of 500 nm and was made of mixed oxides and the other had nominal pore sizes of 200 nm and was made of α-Al₂O₃. The 500 nm membrane demonstrated superior filtration flux and faster processing compared to the 200 nm membrane, though both achieved complete removal of suspended solids. A greater workload of the 500 nm membrane resulted in a progressive irreversible fouling, caused by the smallest-sized suspended particles and macromolecular colloids. Particle size had a greater impact on fouling than particle load. Both membrane treatments induced a spontaneous increase in the concentrations of up to 24 phenolic, secoiridoid and secoiridoidyl phenylethanoid conjugates. This effect can be considered as an additional benefit of the thus clarified olive juices. Further investigations are warranted to elucidate the underlying mechanisms driving these transformations. Full article

It is promising to in situ retrofit the activated sludge process with a membrane bioreactor (MBR) to increase treatment capacity and improve effluent quality in a textile dyeing wastewater treatment plant (WWTP). Membrane selection among commercial products for real engineering applications is critical for this specific wastewater, and little information is available in the literature. This study systematically evaluated the application potential of two flat-sheet microfiltration membranes made of polyvinylidene fluoride (PVDF) and polyether sulfone (PES) in pilot-scale MBRs for in situ retrofitting textile dyeing WWTP. During the four stages with different loads, both membranes achieved nearly the same effluent quality and rejection performance. Both membranes showed little trans-membrane pressure (TMP) increase at an average flux of 15 L/(m²·h) with sub-critical flux characteristics, and showed a sharp TMP increase with super-critical flux characteristics observed at an average flux of 18/22.5 L/(m²·h). After 74 d of filtration, at an average sludge concentration of 12,000 g/L, the PVDF membrane showed less variation in pore size distribution and bubble point pressure, while the PES membrane showed less change in permeability and contact angle. Both membranes met general MBR requirements due to the minimizing pristine effects of both membranes by this specific wastewater matrix. The PVDF membrane showed better anti-fouling capability, especially during high-/over-load stages, and thus was suggested for MBR retrofit, with a sustainable membrane flux below 18 L/(m²·h). Full article

Membrane fouling reduces permeate flux and treatment efficiency, yet most diagnostic methods are destructive and require offline analysis. Optical coherence tomography (OCT) enables in situ, real-time visualization; however, quantitative image extraction of thin foulant layers is often limited by manual processing and subjective thresholding. Here, we develop a reproducible OCT image-analysis workflow that combines band-pass filtering, Gaussian smoothing, and unsharp masking with a dual-threshold subtraction strategy for automated fouling-layer segmentation. Seventeen global thresholding algorithms in ImageJ (289 threshold pairs) were benchmarked against SEM-measured cake thickness, identifying Triangle–Moments as the most robust combination. For humic-acid fouling, the OCT-derived endpoint thickness (14.23 ± 1.18 µm) closely agreed with SEM (15.29 ± 1.54 µm). The method was then applied to other microfiltration foulants, including kaolin and sodium alginate, to quantify thickness evolution alongside flux decline. OCT with the optimized image analysis captured rapid early deposition and revealed periods where flux loss continued despite minimal additional thickness growth, consistent with changes in layer permeability and compaction. The proposed framework advances OCT from qualitative visualization to quantitative, real-time fouling diagnostics and supports mechanistic interpretation and improved operational control of membrane systems. Full article

Multi-product biorefineries, which transform biomass feedstocks into multiple valuable bio-based products, are pivotal for transitioning from a fossil-based economy to a sustainable circular bioeconomy. This work proposes a processing pipeline for fractionating the macrocomponents of Nannochloropsis oceanica, which can serve as a basis for multi-product microalgae biorefineries. It consists of high-pressure homogenization (1200 bar, 1 cycle) to permeabilize the cells, and sequential membrane processing (0.2 µm dia-microfiltration followed by 100 kDa ultrafiltration) and ethanolic extraction (60 mL ethanol/g dry weight, 1 h) to fractionate the disrupted biomass. This biorefinery resulted in four final fractions: (1) enriched in water-soluble proteins (39.0 ± 2.8% w/w proteins; 10.7 ± 0.8% w/w carbohydrates); (2) remaining soluble components (5.7 ± 0.4% w/w proteins; 4.3 ± 0.9% w/w carbohydrates); (3) lipid-rich extract (62.4 ± 5.8% w/w lipids); and (4) non-extracted components (11.8 ± 4.5% w/w lipids), with mass recovery yields of 23.2 ± 2.1%, 6.9 ± 1.0%, 10.6 ± 1.9%, and 60.4 ± 4.1%, respectively. The ultrafiltration protein selectivity was not optimal, despite yielding a 2.6 times more concentrated fraction. Lipid extraction yield (35–60%) and purity (56–68%) were highly affected by the water content of the microfiltration retentate. Overall, 10.0 ± 0.9% of the proteins, 9.7 ± 1.8% of the carbohydrates, and 42.4 ± 13.4% of the lipids of N. oceanica were recovered in fractions 1, 2, and 3, respectively. Full article

Polymeric microfiltration membranes are among the most utilized pressure-driven membranes due to their excellent permeation flux, moderate removal efficiency, low operating pressure, low cost, as well as their potential for reusability and cleanability. Therefore, these membranes are used in different crucial sectors, including the water and wastewater, dairy, beverage, and pharmaceutical industries. However, well-known polymeric microfiltration membranes suffer from their poor hydrophilic properties, causing fouling phenomenon. A reduction in permeate flux, a shortened operational lifespan, and increased energy consumption are the primary negative consequences of membrane fouling. Over the years, a broad spectrum of studies has been performed to modify polymeric microfiltration membranes to improve their hydrophilic, transport, and antifouling characteristics. Despite extensive research, this issue remains a subject of ongoing discussion and scrutiny within the scientific community. This review article provides promising information about different physical and chemical modification methods—such as polymer blending, the incorporation of nanomaterials, surface coating, chemical crosslinking, in situ nanoparticle immobilization, and chemical surface functionalization—for polymeric microfiltration membranes. The physical and chemical modification methods are comparatively evaluated, highlighting their positive and negative aspects, supported by findings from recent investigations. Moreover, promising ideas and future-oriented techniques were proposed to obtain polymeric microfiltration membranes containing superior efficiency, extended service life, and mechanical strength. Full article

This study evaluated powdered activated carbon (PAC) pre-coating as a pretreatment strategy to enhance dissolved organic matter (DOM) removal and control fouling during microfiltration of surface water. Two PAC types (one is coal-based and the other is wood-based), divided into three different particle size ranges (22–44, 44–63, 63–88 μm) using sieves and coating weights ranging from 0.6 to 1.2 and 2.4 mg/cm², were systematically compared. Coating PAC improved the quality of water after filtration and stabilized filtration flux, with smaller PAC particle size ranges exhibiting higher DOM removal efficiencies, achieving maximum removals of approximately 30–35% for DOC and over 50% for UV260 at the highest coating weight, whereas uncoated membranes showed negligible DOM removal. The resulting PAC layer on the membrane increased filtration resistance. Fluorescence EEM and Mw distribution results showed that aromatic and high molecular weight DOM was preferentially adsorbed by PAC before reaching the membrane surface; therefore, their contribution to membrane fouling could be reduced. SEM observations showed differences in the images of deposits formed on the PAC layer. These results indicate that the PAC layer acted as a protective interception zone that reduced direct contact between DOM and the membrane surface, thereby contributing to improved flux stability. The coating effect varied with the weight, type and size range of PAC, highlighting the importance of PAC selection. The findings of this study could contribute to more efficient and sustainable urban water supply system operation and management through water quality improvement and process configuration. Full article

Microplastics represent a pressing global environmental concern due to their persistence, widespread occurrence, and adverse impacts on aquatic ecosystems and human health. Effective removal of these contaminants from water is essential to safeguard biodiversity and ensure water quality. This work focuses on the pivotal role of membrane-based filtration technologies, including microfiltration, ultrafiltration, nanofiltration, reverse osmosis, membrane bioreactors, and dynamic membranes, in capturing and eliminating microplastics. The performance of these systems depends on key membrane characteristics such as pore size, material composition, hydrophilicity, mechanical strength, and module design, which govern retention efficiency, fouling resistance, and operational stability. Membrane filtration offers a highly effective, scalable, and sustainable approach to microplastic removal, outperforming conventional treatment methods by selectively targeting a wide range of particle sizes and morphologies. By highlighting the critical contribution of membranes and filtration processes, this study underscores their potential in mitigating microplastic pollution and advancing sustainable water treatment practices. Full article

The hydrophobic region of semaglutide makes it prone to aggregation in aqueous solution, which leads to serious interception in microfiltration. The influences of pH and low concentrations of salts (NaCl, CH₃COONa, Na₂SO₄ and (NH₄)₂SO₄) on the particle size and zeta potential of semaglutide aggregates were studied in this work. The results showed pH could change the zeta potential on the semaglutide surface, but the impact on semaglutide dispersion was limited. When salts were introduced into aqueous solution, NaCl had a more significant dispersion effect on semaglutide than other salts. Under pH 2.5 or pH 8.0 conditions, the addition of 0.01 mol/L NaCl reduced the average particle size of semaglutide aggregates to below 70 nm. The permeability of semaglutide in microfiltration increased from 60% to 86% under optimized conditions with the PES membrane (0.22 μm), and the adsorption loss also reduced 40%. In addition, this study compared the HPLC detection precision of semaglutide samples prefiltered with different microfiltration filters. Some semaglutide was intercepted by various microfiltration filters, resulting in serious detection errors. When semaglutide was dissolved in the aqueous solution containing 0.01 mol/L NaCl with pH 2.5, the detection error was controlled within 1%. Full article

Contaminated water detoxification remains difficult due to the presence of persistent halo-organic contaminants, such as perfluorooctanoic acid (PFOA) and chlorophenols, which are chemically stable and resist conventional purification methods. Functionalized membrane-based separation and decontamination have garnered immense attention in recent years. Commercially available microfiltration membrane (PVDF) and polymeric non-woven fiber filters (glass and composite) are functionalized with poly(methacrylic acid) (PMAA) that shows outstanding pH-responsive performance and tunable water permeability under ambient conditions perfect for environmental applications. Polymer loading based on weight gain measurements on PMAA–microglass composite fibers (137%) and microglass fibers (116%) confirmed their extent of functionalization, which was significantly greater than that of PVDF (25%) due to its widely effective pore diameter. Presence of chemically active hydrogel within PVDF matrix was validated by FTIR (hydroxyl/carbonyl) stretch peak, substantial decrease in contact angle (68.8° ± 0.5° to 30.8° ± 1.9°), and decrease in pure water flux from 509 to 148 LMH/bar. Nanoparticles are generated both in solution and within PVDF using simple redox reactions. This strategy is extended to PVDF-PMAA membranes, which are loaded with Fe/Pd nanoparticles for catalytic conversion of 4-chlorophenol and PFOA, forming Fe/Pd-PVDF-PMAA systems. A total of 0.25 mg/L Fe/Pd nanoparticles synthesized in solution displayed alloy-type structures and demonstrated a strong catalytic performance, achieving complete hydrogenation of 4-chlorophenol to phenol and 67% hydrogenation of PFOA to its reduced form at 22–23 °C with ultrapure hydrogen gas supply at pH 5.7. These results underscore the potential of hybrid polymer–nanoparticle systems as a novel remediation strategy, integrating tunable separation with catalytic degradation to overcome the limitations of conventional water treatment methods. Full article

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. Full article

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. Full article