Search Results (80)

The application of an ultrafiltration (UF) process with periodic membrane cleaning with the use of alkaline detergent solutions was proposed for the recovery of wash water from car wash effluent. In order to test the resistance of the membranes to the degradation caused by the cleaning solutions, a pilot plant study was carried out for almost two years. The installation included an industrial module with FP100 tubular membranes made of polyvinylidene fluoride (PVDF). The module was fed with synthetic effluent obtained by mixing foaming agents and hydrowax. To limit the fouling phenomenon, the membranes were cleaned cyclically with P3 Ultrasil 11 solution (pH = 11.7) or Insect solution (pH = 11.5). During plant shutdowns, the membrane module was maintained with a sodium metabisulphite solution. Changes in the permeate flux, turbidity, COD, and surfactant rejection were analysed during the study. Scanning electron microscopy (SEM), atomic force microscopy (AFM), differential scanning calorimetry (DSC), and Fourier-transform infrared spectroscopy (FTIR) analysis were used to determine the changes in the membrane structure. As a result of the repeated chemical cleaning, the pore size increased, resulting in a more than 50% increase in permeate flux. However, the quality of the recovered wash water did not deteriorate, as an additional separation layer was formed on the membrane surface due to the fouling phenomenon. Full article

Recovering oil and water from palm oil mill effluent reduces environmental pollution and promotes sustainable practices. An effective method to achieve this is ultrafiltration (UF), which uses semi-permeable membranes to separate oil, solids, and other contaminants from wastewater under pressure. To assess the most effective recovery method, an experimental comparison was conducted between PVDF and α-Al₂O₃ UF membranes at constant permeate of 20–50 LMH for PVDF and 20–70 LMH for α-Al₂O₃ membranes. Both membranes achieved 99.8% chemical oxygen demand (COD) rejection, with oil concentration factor (F_o) of 186.8% and 253.0%, and water recovery (R_w) of 46.6% and 60.5%, respectively. The permeate water quality was superior to the Malaysian discharge standards, and the fat, oil, and grease (FOG) content was suitable for phase separation processes. The optimal permeate fluxes, with stable transmembrane pressures (TMP), were observed at 40 LMH (PVDF) and 60 LMH (α-Al₂O₃). Total resistance (R_t) values were 1.30 × 10¹² m⁻¹ (PVDF) and 1.59 × 10¹² m⁻¹ (α-Al₂O₃). The ratio of irreversible to total resistances (R_ir/R_t) was 0.02 (PVDF) and 0.06 (α-Al₂O₃), indicating minimal irreversible fouling. Overall, the α-Al₂O₃ membrane demonstrated superior performance in oil and water recovery with more stable operation compared to the PVDF membrane. UF membrane technology emerges as an efficient technique for recovering oil and water compared to conventional methods. Full article

Natural rubber skim latex is commonly discarded as waste or turned into skim natural rubber products such as skim crepe and skim blocks. It is challenging to retrieve all residual rubbers in skim latex since it has a very low rubber content and many non-rubber components like protein. Manufacturers conventionally utilize concentrated sulfuric acid as a coagulant. This method generates many effluents and hazardous pollutants that negatively impact the environment. This work presents an innovative method for enhancing the skim latex’s value by employing an ultrafiltration membrane. This study aims to establish a hydrophilic PVDF-TiO₂ mixed-matrix membrane. The skim latex was processed through a membrane-based ultrafiltration process, which yielded two products: skim latex concentrate and skim serum. Skim latex deposits that cause fouling on the membrane surface can be identified by SEM-EDX and FTIR analysis. The PVDF–PVP-TiO₂ mixed-matrix membrane generated the maximum skim serum flux of 12.72 L/m²h in contrast to the PVDF pure membranes, which showed a lower flux of 8.14 L/m²h. CHNS analysis shows that a greater amount of nitrogen, which is indicative of the protein composition, was successfully extracted by the membrane separation process. These particles may adhere to the membrane surface during filtration, obstructing or decreasing the number of fluid flow channels. The deposition reduces the effective size of membrane pores, leading to a decline in flux rate. The hydrophilic PVDF-TiO₂ mixed-matrix membrane developed in this study shows strong potential for application in the latex industry, specifically for treating natural rubber skim latex, a challenging by-product known for its high fouling potential. This innovative ultrafiltration approach offers a promising method to enhance the value of skim latex by enabling more efficient separation and recovery. Full article

Ultrafiltration is essential for wastewater treatment, but it faces challenges such as selectivity, control, and fouling reduction. Incorporating nanoparticles into membranes enhances retention, boosts permeability, and limits fouling, improving overall performance. This study explores the properties of PVDF/Ag-ZnO composite membranes, highlighting the influence of silver-doped zinc oxide nanoparticles on membrane structure, performance, and antimicrobial effect. The non-solvent-induced phase separation (NIPS) method successfully led to the preparation of composite membranes; this method used different doses of silver-doped zinc oxide (Ag-ZnO) nanoparticles with Poly(vinylidene fluoride) (PVDF). Scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), and water contact angle measurements were used to validate the influence of nanoparticles on the composite membrane (PVDF/Ag-ZnO) structure. Conversely, morphology (porosity, surface rigorosity), hydrophilicity, and permeability were analyzed through contact angle, image analysis, and flux measurement. In addition, the membranes were tested for antimicrobial activity against E. coli. Membrane performance shows that the incorporation of 20% w/w Ag-ZnO resulted in improved water permeability, which was about 2.73 times higher than that of a pure PVDF membrane (192.2 L·m⁻²·h⁻¹·bar⁻¹). The membrane porosity showed a linear increase with the number of NPs. The resultant asymmetric membrane was altered to increase the number of pores on the top surface by 61% and the cross-sectional pore surface by 663%. Furthermore, a high antibacterial activity of Ag-ZnO 20% was shown. Full article

Ultrafiltration (UF) is increasingly used in the food industry and for wastewater treatment and water reuse. Knowledge of the membrane properties that stabilise during the initial period of module operation in an industrial plant is essential for design purposes. This paper presents the experimental tests carried out using a pilot plant with an industrial PCI B1 membrane module. The module was equipped with tubular FP100 (100 kDa) polyvinylidene fluoride (PVDF) membranes used to separate carwash wastewater. The effect of membrane compaction during the first few days of the process on changes in permeate flux and dextran (40–500 kDa) separation rate was investigated. The effect of fouling, membrane washing with P3 Ultrasill 11 solution (pH = 12) and maintenance with sodium metabisulfite solution on the stabilisation of the technological performance of the plant was determined. Full article

Car wash wastewater (CWW) is complex waste that may be effectively treated by the ultrafiltration (UF) process. However, one of the most important challenges in implementing this process on an industrial scale is the fouling phenomenon membrane aging. Indeed, these may lead to a reduction in UF performance possibly associated with a loss in integrity of the fouled/aged membrane. Therefore, the main aim of the current study was to provide a comprehensive investigation on the changes in the separation properties of aged FP100 ultrafiltration membranes made of polyvinylidene fluoride (PVDF) with respect to their application for long-term treatment of CWW. For this purpose, studies were conducted for new membranes and membranes previously used for over 5 years in a pilot plant. As a feed, solutions of dextran, solutions of model organism Escherichia coli and synthetic CWW were used. It has been found that PVDF membranes demonstrated poor stability when in frequent contact with chemicals periodically applied for membrane cleaning. Indeed, the aged membranes were characterised by the increased porosity. However, it is important to note that membranes aging had no significant impact on the permeate quality during the UF process of synthetic CWW. Indeed, the obtained permeate was characterised by the turbidity lower than 0.25 NTU. Likewise, with regard to the separation of E. coli, the aged PVDF membranes ensured the high process efficiency and over 99.99% bacterial retention. In the interest of the growing potential of PVDF membrane in CWW treatment, the results obtained in the current work complement the findings made in this field. Full article

Currently, the world faces serious challenges in meeting the growing demand for clean water. The present paper demonstrates the possibility of using the ultrafiltration (UF) process to reuse water from wastewater generated in car washes. Car washes commonly use foaming agents with dyes, which, although they are not necessary for washing cars, may hinder water reuse. For this reason, the aim of this work was to investigate the effect of the dyes present in car wash wastewater on the membrane fouling intensity. For this purpose, experimental tests were conducted with the application of a pilot plant with an industrial PCI B1 membrane module. The module was equipped with tubular FP100 (100 kDa) polyvinylidene fluoride (PVDF) membranes. For the feed, two types of cleaning agents and synthetic wastewater were used. The results obtained in the current study demonstrated that the UF membranes allowed the obtainment of the permeate characterized by high quality. In addition, it has been shown that the presence of Indigo carmine dye in the wastewater led to an increase in the fouling intensity. To sum up, it should be pointed out that the findings presented in the current study may be of key importance in the design of pilot installations used for the treatment of car wash wastewater. Full article

The utilization of membrane technologies in winemaking has revolutionized various stages of production, offering precise and efficient alternatives to traditional methods. Membranes, characterized by their selective permeability, play a pivotal role in enhancing wine quality across multiple processes. In clarification, microfiltration and ultrafiltration membranes, such as ceramic or polymeric membranes (e.g., polyethersulfone or PVDF), effectively remove suspended solids and colloids, resulting in a clearer wine without the need for chemical agents. During stabilization, membranes such as nanofiltration and reverse osmosis membranes, often made from polyamide composite materials, enable the selective removal of proteins, polysaccharides, and microorganisms, thereby improving the wine’s stability and extending its shelf life. Additionally, in dealcoholization, membranes like reverse osmosis and pervaporation membranes, typically constructed from polydimethylsiloxane (PDMS) or other specialized polymers, facilitate the selective removal of ethanol while preserving the wine’s flavor and aroma profile, addressing the increasing consumer demand for low-alcohol and alcohol-free wines. This article provides a comprehensive analysis of the advancements and applications of membrane technologies in winemaking. Full article

With the widespread use of plastic products, microplastic (MP) pollution has become an important factor threatening the water environment and human health. Ultrafiltration (UF) technology, based on organic polymer membranes, is a common method to remove MPs in water treatment processes, offering high removal efficiency and scalability. However, in water treatment plants (WTPs), oxidation pretreatment is often applied before UF, and the presence of oxidants can affect membrane performance. In this study, we constructed a polyvinylidene fluoride (PVDF) ultrafiltration membrane for a gravity filtration system to investigate the impact of sodium hypochlorite oxidation pretreatment on the removal of polystyrene (PS) MPs under gravity filtration. As a result, pre-chlorination reduced PS microplastic deposition on membranes by improving flux stability (15.1%) but significantly decreased the removal rate (from 36.6% to 22.6%). Pre-oxidation facilitated a shift in fouling behavior toward intermediate blocking while reducing standard blocking and enhancing irreversible fouling recovery. However, continuous chlorine exposure increased membrane porosity and pore size, substituted fluorine with chlorine, and led to organic carbon leaching, indicating pre-oxidation jeopardizes membrane stability and separation performance. These findings provide insights into the development of novel strategies aimed at enhancing the efficiency and sustainability of membrane treatment processes in WTPs. Full article

Ultrafiltration membranes in the fields of water treatment and biomedicine should have high permeability as well as antibacterial and antifouling capabilities. In this study, based on the hydrophilicity of fullerol (C₆₀(OH)_n) and the bacteriostatic properties of silver (Ag), a fullerol–silver (C₆₀(OH)_n-Ag) complex was prepared as a multifunctional additive. A polyvinylidene fluoride (PVDF)-composited C₆₀(OH)_n-Ag ultrafiltration membrane (C₆₀(OH)_n-Ag/PVDF) was prepared by immersion precipitation phase transformation. Addition of the C₆₀(OH)_n-Ag complex improved the permeability and retention of the traditional PVDF membrane. Compared with the traditional PVDF membrane, the surface water contact angle of the modified PVDF and C₆₀(OH)_n-Ag ultrafiltration membrane was reduced from 75.05° to 34.50°, its pure water flux increased from 224.11 L·m⁻²·h⁻¹ to 804.05 L·m⁻²·h⁻¹, the retention rate on bovine serum protein was increased from 75.00% to 96.44% and the flux recovery rate increased from 64.91% to 79.08%. The C₆₀(OH)_n-Ag/PVDF ultrafiltration membrane had good inhibitory effects on Escherichia coli and Staphylococcus aureus, while the PVDF ultrafiltration membrane had no obvious inhibitory effects. Full article

In the present study, the possibility of recovering water in a car wash station was presented. The resistance of automotive coatings to washing water recovered at 50% and 70% from wastewater generated at car wash was tested. Wastewater treatment was carried out by ultrafiltration (UF) using tubular polyvinylidene fluoride (PVDF) membranes (100 and 200 kDa) manufactured by the PCI company. The membranes retained oil contamination, suspended solids, and over 60% of surfactants. For comparison, the 0.5% Turbo Active Green solution, used at professional car washes, was also applied in paint resistance studies. The tested solutions washed the painted surfaces of samples taken from car doors for 8 days. The resistance of automotive coatings to washing solutions was assessed by measuring gloss, Log Haze, RIQ, and Rspec parameters. Scratch resistance was also assessed. The results obtained in the current study indicated that the use of water recovered from wastewater did not deteriorate the quality of the car paint coating. Full article

The commercial ultrafiltration tubular polyvinylidene fluoride (PVDF) (100 and 200 kDa) and polyethersulfone (PES) (4 kDa) membranes were applied for filtration of car wash wastewater. Intensive fouling was noticed, which caused an over 50% flux reduction during 3–5 h of the filtration process. This phenomenon was reduced by washing the membranes with an alkaline cleaning agent (pH = 11.5), which is used in car washes to remove insects. The filtration/membrane washing cycle was repeated many times to achieve stable operation of the membrane modules. It has been found that cyclic repeated washing did not deteriorate the performance of the membranes. Despite frequent cleaning of the membranes (every 5–7 h), irreversible fouling occurred, resulting in a 20% reduction in the initial permeate flux. However, the formation of a filter cake definitely improved the separation degree and, for the 200 kDa membranes, separation of the wastewater components was obtained as it was for the 4 kDa membranes, while, at the same time, the permeate flux was 5 times higher. Full article

In the present study, oily wastewater generated during car washing was separated using ultrafiltration (UF). Wastewater was collected from the settling tank of two manual car washes. In addition to pollutants removed from cars, such wastewater contains surfactants, the impact of which on the process of ultrafiltration has been analyzed. For this purpose, the application of commercial UF polyethersulfone (PES) membranes (10 and 100 kDa) and polyvinylidene fluoride (PVDF) tubular membranes (100 kDa) was comprehensively examined. Almost 100% removal of oil contaminants was achieved; however, intensive fouling was noticed. The membrane morphology and deposit composition were studied using a scanning electron microscope coupled with energy dispersion spectrometry. The fouling phenomenon was reduced by washing the membranes with an alkaline cleaning agent (pH = 11.5), which is used in car washes to remove insects. The filtration/membrane washing cycle was repeated many times to achieve stable operation of the membrane modules. The UF process was carried out for 120–140 h, and the separation efficiency was analyzed based on the rejection of dextrans, COD, BOD, total N and P, turbidity, and anionic surfactants. It has been found that cyclic repeated washing did not deteriorate the membrane’s performance, and a permeate with a turbidity of 0.12–0.35 NTU was obtained. Thus, cleaning agents used for washing cars can also be used for membrane cleaning. Full article

Electrically conductive membranes (ECMs) have emerged as a multifunctional separation technology that integrates membrane filtration with electrochemical reactions. Physical stability remains a critical challenge for ECMs synthesized by coating polymer membranes with conductive materials. In this article, polydopamine (PDA) and polyethyleneimine (PEI) were used to facilitate the synthesis of significantly more stable ECMs using poly(vinylidene fluoride) (PVDF) ultrafiltration membranes and carbon nanotubes (CNTs). Four different synthesis methods were compared in terms of the final surface stability and separation properties: (1) CNTs deposited on PEI-crosslinked PDA-coated PVDF membranes, (2) PEI-crosslinked CNTs deposited on PDA-coated PVDF, (3) PDA, PEI and CNTs sequentially deposited layer-by-layer on PVDF, and (4) PEI-crosslinked PDA deposited on CNT-coated PVDF. The results revealed that method 1 generated ECMs with the greatest physical stability, highest electrical conductivity (18,518 S/m), and sufficient permeability (395.2 L/(m²·h·bar). In comparison, method 2 resulted in membranes with the highest permeability (2128.5 L/(m²·h·bar), but with low surface conductivity (502 S/m) and poor physical stability (i.e., 53–75% lower peel-off forces compared to other methods). Overall, methods 1, 3, and 4 can be used to make highly conductive membranes with a 97–99% removal of methyl orange by electrochemical degradation at −3 V. Full article

Zeolite serves as a promising additive for enhancing the hydrophilicity of polymeric membranes, yet its utilization for bolstering the mechanical strength of the membrane remains limited. In this study, poly(vinylidene fluoride) (PVDF) membranes were modified by incorporating various concentrations of zeolite (0.5–2 wt%) to improve not only their mechanical properties, but also other features for water filtration. Membranes with and without zeolite incorporation were fabricated via a dry–wet phase inversion technique, followed by the application of a series of characterization techniques in order to study their morphological structure, mechanical strength, and hydrophilicity. The membrane filtration performance for each membrane was evaluated based on pure water flux and Bovine Serum Albumin (BSA) rejection. Field-Emission Scanning Electron Microscopy (FESEM) images revealed a dense, microvoid-free structure across all of the PVDF membranes, contributing to a high pristine PVDF membrane tensile strength of 14 MPa. The addition of 0.5 wt% zeolite significantly improved the tensile strength up to 19.4 MPa. Additionally, the incorporation of 1 wt% zeolite into PVDF membrane yielded improvements in membrane hydrophilicity (contact angle of 67.84°), pure water flux (63.49% increase), and high BSA rejection (95.76%) compared to pristine PVDF membranes. To further improve the characterization of the zeolite-modified PVDF membranes, the Support Vector Regression (SVR) model was adopted to estimate the molecular weight cut off (MWCO) of the membranes. A coefficient of determination (R²) value of 0.855 was obtained, suggesting that the SVR model predicted the MWCO accurately. The findings of this study showed that the utilization of zeolite is promising in enhancing both the mechanical properties and separation performance of PVDF membranes for application in ultrafiltration processes. Full article