Nanofiltration Membrane Process Research Articles

Erratum to: Reliability of Nanofiltration Membrane Process for Brackish Water Treatment in Baghdad City: Module Modeling and Simulation

Erratum to: Reliability of Nanofiltration Membrane Process for Brackish Water Treatment in Baghdad City: Module Modeling and Simulation

Efficacies and mechanisms of different cleaning strategies for NF and RO membranes in a full-scale zero liquid discharge system

Membrane fouling conditions can be distinct for multi-step nanofiltration (NF) and reverse osmosis (RO) membrane processes in zero liquid discharge (ZLD) system. Customizing cleaning procedures according to fouling characteristics is imperative to improve the overall cleaning efficiency of the system. Herein, we performed four different “alkaline + acid” cleaning procedures, including alkaline solution (NaOH), acid solution (citric acid), metal chelating agents (Na2EDTA), and surfactants (SDS), on five fouled NF and RO membranes from a full-scale ZLD system for cold-rolling wastewater brine treatment. The“alkaline + acid” cleaning procedures were effective for organic and inorganic combined fouling removal in two-stage NF process, but failed to remove SiAl complex scaling completely for the 2nd RO process. Due to the slight membrane fouling, both performance and surface properties of 1st and 3rd pass RO membranes did not change significantly after the cleaning. The high pH-induced solubilization were the major mechanism for the removal of the SiAl complex. Na2EDTA/SDS addition caused the decrease of foulant-foulant and foulant-membrane interactions. Customizing membrane cleaning procedures based on membrane fouling characteristics can facilitate the stable operation of hybrid membrane system for the practical industrial wastewater ZLD treatment.

Reliability of Nanofiltration Membrane Process or Brackish Water Treatment in Baghdad City: Module Modeling and Simulation

Reliability of Nanofiltration Membrane Process or Brackish Water Treatment in Baghdad City: Module Modeling and Simulation

Highly tunable structure-by-design polymer brush membranes for organic solvent nanofiltration

Synthetic polymeric nanofiltration membrane processes offer an alternate low-energy option to energy-intensive distillation to fractionate similar size organic solvents for chemical, petroleum, food and biotechnology industries. Here, we synthesize and test a new class of structure-by-design hydrophilic polymeric brush membranes, that address the limitations of commercial polymer membranes, are tunable and exhibit commercially relevant filtration performance. Because these brush membranes are grafted by Single Electron Transfer-Living Radical Polymerization (SET-LRP) and replace statistically random phase inversion or interfacial polymerization used for synthesizing commercial polymer membranes, their porous structure can be remodeled by varying their morphology and chemistry. We graft hydroxyethyl methacrylate (HEMA) brush structures with short and long crosslinkers, demonstrate two competing phenomena - pore stiffening and opening - and obtain high selectivity at reasonable permeability for commercially relevant methanol/toluene separation. This new class of stable, tunable, and scalable membranes offers exciting opportunities to reduce energy for separation of organic solvents.

Occurrence and treatment effect assessment of organophosphorus flame retardants in source and drinking water, Jinan, China.

The occurrence and removal efficiencies of organophosphorus flame retardants (OPFRs) by traditional treatment processes (pre-flocculation, sand filtration, and post-chlorination processes) and advanced treatment processes (i.e., ozone and granular activated carbon (GAC), ultraviolet/hydrogen peroxide (UV/H2O2), GAC alone, ultrafiltration membrane, nanofiltration membrane) were examined in two municipal plants and a pilot plant in Jinan, China. The concentrations of six OPFRs in raw waters were at levels of 16.8-100.0ng/L, and three OPFRs were below the detection limits. The traditional treatment processes could not effectively remove the OPFRs (the removal efficiency was - 12.0-15.4%). The advanced oxidation with ozone and GAC (the removal efficiency was 35.6-60.3%) or UV/H2O2 and GAC processes (the removal efficiency was 68.0-86.7%) were more effective than the traditional water treatment processes. The removal efficiencies of ultrafiltration process for the OPFRs was 11.2-69.8% which were positively correlated with the logKow values of OPFRs. The nanofiltration membrane process with ultrafiltration membrane process as the pretreatment was the most effective process (the removal efficiencies were almost to 100%). These results imply that the combination of ultrafiltration membrane and nanofiltration membrane is an effective measure in the treatment of OPFRs in municipal drinking water plants.

Bromelain extraction using single stage nanofiltration membrane process.

Pineapple (Ananas Comosus) is a tropical fruit having exceptional juiciness, vibrant tropical flavor and immense health benefits. Pineapples are not only taken fresh but they have been commercialized in the canning industry. Morris cultivar is mostly supplied to the canning industry where only the flesh is utilized and the rest of the pineapple (50wt%) such as the core, stem, peels and crown are discarded as wastes. In the extraction of bromelain which is a vital proteolytic enzyme the whole pineapple including its peels, core, stem and crown can be utilized. This enzyme is very valuable and considered as a food supplement with a wide range of therapeutic benefits. Thus, in this study, bromelain is extracted from the flesh, crown, stem, core and peel of pineapples using simple one stage hollow fiber nanofiltration membrane process. The different parts of the pineapple were crushed to extract the juice. The juice was then centrifuged and the supernatant was then passed through a nanofiltration membrane. Results revealed the retentates from the different pineapple parts contain high amounts of bromelain in descending order flesh > peel > core > crown > stem. The amount of bromelain activity increased after every process especially after freeze drying.

A facile green “wastes-treat-wastes” strategy: Electrogenerated chloramines for nanofiltration concentrate recirculation

Use of nanofiltration (NF) membrane to reuse the secondary wastewater suffers from severer biofouling and refractory concentrate. To realize sustainable NF membrane processes in water purification, the electro-oxidation (EO) process using boron-doped diamond (BDD) anodes was applied in current study to treat the NF concentrate for removal of organic contaminates and nutrients using simultaneously controllable in-situ generation of chloramines. The electrolytic effluent would be mixed with the raw secondary wastewater as the feed of subsequent NF process for conducting chloramination to mitigate membrane biofouling. It was found that under a constant current density of 30 mA/cm2, the chloramine formed with the electrolysis while its concentration reached the maximum at 30 min of electrolysis when NH3–N was 7 mg/L and Cl− concentration was below 500 mg/L. The complete elimination of antibiotics and bacteria can be attained in the hybrid NF-EO process thanks to the in-situ simultaneous generation of large amount of chloramine. In particular, the membrane biofouling was effectively alleviated to maintain a stable permeate flux during the 160-h period of sustainable operation. Our study provides a promising “wastes-treat-wastes” strategy for sustainable reuse of secondary wastewater.

Membrane fouling behaviors in a full-scale zero liquid discharge system for cold-rolling wastewater brine treatment: A comprehensive analysis on multiple membrane processes

The challenge of water scarcity drives zero liquid discharge (ZLD) treatment to maximize reuse of industrial wastewater. Deciphering the characteristics and mechanisms of membrane fouling in the membrane-based ZLD system is crucial for the development of effective fouling control strategies. However, current studies only focused on the membrane fouling of single step, lacking in-depth understanding on the ZLD systems using multiple membrane processes. Herein, membrane fouling characteristics and mechanisms in a full-scale ZLD system for cold-rolling wastewater brine treatment were investigated via a comprehensive analysis on multiple nanofiltration (NF) and reverse osmosis (RO) membrane processes. The membrane fouling behaviors showed distinct characteristics along the wastewater flow direction in the ZLD system. Increasing amounts of foulants were deposited on the membrane surfaces with the sequence of the 1st pass RO, 1st stage NF, and 2nd stage NF processes. The organic fouling and silica scaling were more intensive in the 1st stage NF and 2nd stage NF for treating the brine of the 1st pass RO, as the foulants were rejected and concentrated by previous membrane processes. Severe inorganic fouling, containing amorphous SiO2, Al2O3, and Al2SiO5, occurred on the membrane surface of the 2nd pass RO membrane, due to the recirculated high-concentration silica, high water recovery, and concentration polarization. For the 3rd pass RO process, both the amounts of organic and inorganic foulants decreased dramatically, due to the low foulant concentration in its influent. This work provides a comprehensive understanding of membrane fouling in a membrane-based ZLD system, facilitating the development of membrane fouling control strategies for multiple membrane processes.

Water Recovery from Urban Wastewater for Irrigation using Ultrafiltration and Nanofiltration: Optimization and Performance

AbstractThe shortcomings of conventional processes for treating urban wastewater subjected to secondary treatment, in order to use this water for irrigation, are well known. Alternative advanced treatment techniques are required instead. This study aims to use single‐stage ultrafiltration (UF) or nanofiltration (NF) membrane processes to produce irrigation water from biologically treated urban wastewater. For this purpose, the effects of four process variables (membrane type, cross flow velocity, temperature, and transmembrane pressure) on process performance parameters (permeate flux, concentrations/removal efficiencies of contaminants) are analyzed through Taguchi experiment design. Temperature and membrane type are found to have the biggest effect on UF, whereas the membrane type is the most significant variable for the NF. Moreover, the use of membrane permeate for landscaping and agricultural irrigation based on optimal conditions is assessed with reference to the criteria imposed by national regulation/international guidelines. Water in various quality categories is produced using different settings for 28 distinct specific parameters with reference to the membrane type, process performance, and the irrigation method. The results indicate that single‐stage UF or NF membranes with high recovery rates can be used for wastewater subjected to secondary treatment, to recover irrigation water at low pressure and high water permeate flux.

Functionalized boron nitride ceramic nanofiltration membranes for semiconductor wastewater treatment

Boron nitride (BN) nanomaterials were used to enhance the separation performance of membranes due to their ability to create more nanochannels with excellent chemical stability. Two different functionalization methods, including strong acid oxidation and a tannic acid (TA)-assisted exfoliation process, were explored to introduce hydroxyl groups on BN surfaces. We also propose a novel method for the fabrication of ceramic nanofiltration (NF) membranes with optimal functionalized BN loadings on ceramic ultrafiltration (UF) membrane substrates. The functionalized BN-coated ceramic NF membrane exhibited a promising separation performance for both particulate and organic contaminants by modifying the surface chemistry of the ceramic membrane and reducing membrane pores by adding nanochannels. Compared to the performance of the ceramic UF membrane alone, filtering ceramic UF membrane permeate through the functionalized BN-coated ceramic NF membrane increased an additional rejection of 20.4% for dissolved silica and 59.8% for humic acid, respectively. Collectively, the results provide a basis for the optimization of membrane-based semiconductor wastewater treatment by creating a hybrid of the ceramic UF and NF membrane processes. In turn, our findings not only facilitate the achievement of national regulatory standards for wastewater discharge but also provide crucial insights into the transport dynamics of particulate and organic contaminants.

Machine learning-based modeling and analysis of PFOS removal from contaminated water by nanofiltration process

Per- and polyfluoroalkyl substances (PFAS) are hazardous chemicals that have been widely used in different industries and released into the environment through contaminated effluents. Nanofiltration (NF) is a promising process for removing PFAS from the effluents. This study aimed to model and analyze the performance of the NF membrane process in perfluorooctanesulfonic acid (PFOS) removal from contaminated effluents using machine learning (ML) algorithms. The modeling output of seven ML algorithms was evaluated using statistical indexes of determination coefficient (R2) and mean squared error (MSE) for robustness. The results demonstrated that random forest (RF), gradient boosting machine (GBM), and AdaBoost models were the most robust for the NF process. Accordingly, the optimization of these procedures was accomplished using a grid search. The optimized models were deeply analyzed using permutation variable importance (PVI) to quantify the relative importance of operating variables. The three ML procedures (RF, GBM, AdaBoost) presented high prediction strength for PFOS removal from contaminated effluents with low MSE values (4.726, 2.450, 2.879) and high R2 values (0.930, 0.975, 0.968). In addition, PVI-RF showed decreasing importance of pressure, initial PFOS concentration, membrane type, trivalent cation, pH, divalent cation and monovalent cation consecutively.

Application of Nanofiltration and Reverse Osmosis in Wastewater Treatment Containing Ethylene Glycol from South Pars Gas Complex Wastewater

Today, industrial wastewater discharge has become one of the serious problems of governments. Industrial wastewater contains harmful and dangerous compounds that can endanger human health and the environment. In addition, in the oil, gas, and petrochemical industries, ethylene glycol is used for various purposes, and its removal from wastewater has become a challenge. Industries located on the shores of the Persian Gulf are one of the sources of production of this type of wastewater. In this study, the performance of Nanofiltration (NF) and Reverse Osmosis (RO) membrane processes for treatment of wastewater containing ethylene glycol (EG) from South Pars Gas Complex (SPGC) are investigated and compared. Various process parameters such as pressure, flowrate, and EG removal percentage as well as performance and characteristics of the membrane such as flux and fouling are discussed. It has been observed RO has better performance and less fouling than NF. However, the NF membrane has higher flux due to less compression. RO process achieved 80-99% and NF achieved 60-80% EG rejection during various pressure and flowrates.

Water treatment intensification using a monophasic hybrid process coupling nanofiltration and ozone/hydrogen peroxide advanced oxidation

This study assesses the feasibility of designing a hybrid ozonation / nanofiltration membrane process that can simultaneously oxidize and reject contaminants while exhibiting reduced membrane fouling. An innovative monophasic configuration, in which a pre-ozonated water was mixed at the membrane cell inlet to the water to be treated doped with H2O2 (at equimolar concentrations of H2O2 and O3), was implemented, allowing to avoid an ozone-enriched gas flow in the membrane cell. Thus, two commercial polymer membranes, NP10 (polyethersulfone) and NF270 (polyamide), were assessed in a cross-flow configuration despite their low-ozone compatibility compared with ceramic membranes. Ozone removal yields>90% were obtained whatever the studied water matrix. Fast ozone decomposition initiation reactions with H2O2 and with some moieties of the natural organic matter were responsible for a low ozone lifetime in the liquid bulk, allowing to protect the membranes from ozone and radicals. Deethylatrazine (DEA) was used as a radical tracer, allowing to determine Rct values with orders of magnitude of 10-6 and 10-7 in drinking water and a river water sample, respectively. The concentrations of two pharmaceuticals, carbamazepine and sulfamethoxazole, in the permeate and the retentate were lower than the detection limit in drinking water when the PES membrane was tested. During treatment of the river water sample, membrane fouling dropped by a factor two while there was no alteration of both the PES and PA membranes. Finally, thanks to synergistic effects induced by contaminant oxidation and rejection, dissolved organic content and DEA were both removed at around 70% when PA membrane, exhibiting a tighter microstructure than PES, was used.

Host-guest nanofiltration membranes having amino-complexed cucurbituril supramolecular channel for monovalent/divalent salts separation

Nanofiltration (NF) is widely used in separation of ions with different sizes and charges. However, thin-film composite NF membrane is hard to reach satisfied selectivity for monovalent/divalent salts separation. Herein, a novel host-guest NF membrane was designed and fabricated with cucurbituril-polyethyleneimine (CB-PEI) complex, which provided a “ring-like” supramolecular channel. The results indicated that CB-PEI/PSf membrane showed attractive separation performance for monovalent/divalent salts separation, purification and desalination of small molecule solutions. The as-prepared CB-PEI/PSf membrane exhibited superior pure water permeability up to 25.6 L·m−2·h−1·bar−1, and salt rejections of 97.4%, 90.6%, 41.9% and 12.4% to MgSO4, Na2SO4, MgCl2 and NaCl, respectively. The monovalent/divalent selectivelies for NaCl/MgSO4 and NaCl/Na2SO4 reached up to 30.0 and 8.9, respectively. Besides, the CB-PEI/PSf membrane exhibited very high separation factors for medicine/NaCl and dye/NaCl mixtures. Moreover, NF membrane processes were designed and operated for monovalent/divalent mixed salt separation by using CB-PEI/PSf membrane. The NaCl with mass fraction above 98% was successfully recovered after the single-stage membrane separation of NaCl/MgSO4 mixture and the two-stage membrane separation of NaCl/Na2SO4 mixture. Therefore, this novel host-guest NF membranes and process design provide a valuable basis for the industrial application of monovalent/divalent salts separation.

Water recovery from yarn fabric dyeing wastewater using electrochemical oxidation and membrane processes.

This study intended to evaluate and compare the efficiency of electrochemical oxidation (EO), nanofiltration (NF), and reverse osmosis (RO) membranes processes in the treatment of yarn fabric dyeing wastewater (YFDW) in terms of chemical oxygen demand (COD) removal, color removal, salinity reduction, and conductivity removal. EO tests of the textile effluent were conducted under various current densities and solution pH conditions employing a graphite electrode. Membrane filtration experiments were conducted using two different NF membranes: NP010 and NP030 and two distinct RO membranes: BW30 and SW30 flat-sheet membranes. The experimental results showed that NF membrane process is not suitable for yarn fabric wastewater treatment showing low removal efficiencies for COD, color, and conductivity. However, both EO and RO membranes could reduce COD and color to high removal performances. EO results showed more than 99% of color removal and 80% of COD elimination at pH = 6 and current density of 50 mA/cm2 after 180 min of reaction. Using RO membrane for yarn fabric wastewater treatment demonstrated relatively complete removal of color concentration and 98% of COD elimination. However, EO process showed less performance in conductivity removal efficiency compared to the RO membranes. EO treatment of YFDW decreased conductivity by 31.2%, whereas RO membrane process reduced conductivity to a greater extent and recorded 97.1% of removal elimination percentage. Therefore, the treated water by RO membrane could be recycled back to the process such as washing and dyeing, in that way offering economic profits by decreasing water consumption and wastewater treatment cost. PRACTITIONER POINTS: Electrochemical oxidation and membrane filtration processes were combined for the treatment of yarn fabric dyeing wastewater (YFDW). A 100% color removal of color and 98.5% COD elimination efficiencies were obtained for the electrochemical oxidation (EO) + RO combined process. EO treatment of YFDW decreased conductivity by 32.7%, whereas the RO membrane process reduced conductivity to a greater extent and recorded 97.7% of removal elimination percentage.

Characterization of residual organic matter in oil sands steam assisted gravity drainage produced water treated by ceramic nanofiltration membranes

Steam assisted gravity drainage (SAGD) is an energy and water intensive oil recovery technology for in-situ extraction of oil sands bitumen. It is essential to recycle the SAGD produced water (PW) to reduce water consumption and improve the energy efficiency of the process. This work investigated the removal of residual organic matter (ROM) in the SAGD-PW by the ceramic nanofiltration (NF) membrane process. The overall removal efficiency of ROM in the SAGD-PW was influenced by their polarities, membrane pore size, and membrane material. Non-polar oil components including saturated and aromatic hydrocarbons were completely removed; meanwhile, approximately 80% of polar components were removed by the membrane nanofiltration. Membrane nanofiltration significantly altered the chemical composition of the SAGD-PW by removing 95.0–98.3% of total solvent extracted material (TSEM). The chemical fingerprints of the solvent extracted materials in the feed and permeate samples were characterized. The profile of polar components such as naphthenic acids (NAs) in the permeate samples is significantly different from that in the feed samples.

Removal of Copper, Nickel, and Zinc Ions from an Aqueous Solution through Electrochemical and Nanofiltration Membrane Processes

Heavy metal contamination in water is a major health concern, directly related to rapid growth in industrialization, urbanization, and modernization in agriculture. Keeping this in view, the present study has attempted to develop models for the process optimization of nanofiltration (NF) membrane and electrocoagulation (EC) processes for the removal of copper, nickel, and zinc from an aqueous solution, employing the response surface methodology (RSM). The variable factors were feed concentration, temperature, pH, and pressure for the NF membrane process; and time, solution pH, feed concentration, and current for the EC process, respectively. The central composite design (CCD), the most commonly used fractional factorial design, was employed to plan the experiments. RSM models were statistically analyzed using analysis of variance (ANOVA). For the NF membrane, the rejection of Zn, Ni, and Cu was observed as 98.64%, 90.54%, and 99.79% respectively; while the removal of these through the EC process was observed as 99.81%, 99.99%, and 99.98%, respectively. The above findings and a comparison with the conventional precipitation and adsorption processes apparently indicate an advantage in employing the NF and EC processes. Further, between the two, the EC process emerged as more efficient than the NF process for the removal of the studied metals.

Nanofiltration membrane processes for water recycling, reuse and product recovery within various industries: A review

Nanofiltration (NF) membrane has been applied for the treatment of wastewater owing to its unique features such as higher selectivity towards divalent/polyvalent ions while allowing permeation for monovalent ions and small molecules of less than 100 Da. Thus, the use of NF in wastewater treatment is promising for water recycling, reuse, and recovery of other valuable products in industrial wastewater treatment. This review highlights the current application of NF for water recycling, reuse, and product recovery within multiple industries such as textile, food, oil and gas, mining, tannery, pharmaceutical as well as pulp and paper industry. The performance of NF either as stand-alone or integrated with other processes for improving the overall treatment efficiency and minimizing membrane issues is discussed. Finally, future perspectives for NF applications in industrial wastewater treatment for water recycling, reuse, and product recovery are discussed.

Symmetric forward osmosis membrane coupled with dendritic draw solute: New insights into sustainable properties

The development of current forward osmosis (FO) technology has experienced a significant challenge because of the ineliminable internal concentration polarization effect in conventional asymmetric FO membranes as well as the extremely energy-intensive recovery process of the common draw solutes (e.g., NaCl). Here, we report, for the first time, a coupling system comprising a symmetric FO (SFO) membrane and a series of macromolecular draw solutes (MDS). The lack of a support layer in the SFO membrane facilitates free MDS diffusion, thus completely eliminating the ICP effect. As a result, the obtained reverse flux selectivity (JwFO/JsFO, ratio of water flux to reverse salt flux) of the SFO/MDS system was approximately 5000, 20000, and 40000 L mol−1, which were 2–3 orders of magnitude higher than that of the conventional salt-based FO system. Moreover, due to the low rejections to inorganic salts, the SFO membrane exhibited the unique ability for allowing most NaCl to pass through while retained most MDS simultaneously, which endowed a great utility of the SFO/MDS system for desalination of textile wastewater. Subsequently, the MDS with large molecular weights could be readily recovered by a facile nanofiltration membrane process with a much higher water flux than that of the conventional reverse osmosis process at the same operating pressure, indicating the high energy-saving capacity of the SFO/MDS system. Given the significant compatibility of SFO and MDS, our study provides a new coupling strategy for the development of sustainable FO technologies.

Modeling of Nanofiltration Process Using DSPM-DE Model for Purification of Amine Solution.

The formation of heat stable salts (HSS) during the natural gas sweetening process by amine solvent causes many problems such as corrosion, foaming, capacity reduction, and amine loss. A modeling study was carried out for the removal of HSS ions from amine solution using nanofiltration (NF) membrane process that ensures the reuse of amine solution for gas sweetening. This model studies the physics of the nanofiltration process by adjusting and investigating pore radius, the effects of membrane charge, and other membrane characteristics. In this paper, the performance of the ternary ions was investigated during the removal process from methyl di-ethanol amine solution by the nanofiltration membrane process. Correlation between feed concentration and permeate concentration, using experimental results with mathematical correlation as Ci,p = f (Ci,f) was used in modeling. The results showed that the calculated data from the model provided a good agreement with experimental results (R2 = 0.90–0.75). Also, the effect of operating conditions (including feed pressure and feed flow rate on ions rejection and recovery ratio across the flat-sheet membrane) was studied. The results showed that the recovery and rejection ratios of the NF membrane depend on the driving pressure across the membrane. While the driving pressure is affected by the feed flow conditions and feed pressure.