Fouling Of Nanofiltration Membranes Research Articles

Optimization of Lithium Separation from NCA Leachate Solution: Investigating the Impact of Feed Concentration, Pressure, and Complexing Agent Concentration

Recycling lithium batteries (LIB) has emerged as an attractive solution in the global pursuit of environmentally friendly practices. The aim of achieving zero–waste hydrometallurgical technology is within reach. This research focuses on utilizing the low-pressure nanofiltration process to address this challenge by separating lithium ions from other ions and achieving a desirable permeate flux. The NCA battery leachate concentrate was obtained through a hydrometallurgical process involving sulfuric acid–peroxide. To ensure the prevention of potential nanofiltration membrane (TS80) fouling, the concentrate is initially filtered using an ultrafiltration membrane (UH004) to remove any particles. The research investigates the impact of pressure (4, 6, and 7 bar), solution concentration (concentrate, 10x, and 50x dilution), and the concentration of the complexing agent (EDTA) on the desired separation performance. The investigation reveals that pressure variations exhibit consistent rejection rates, remaining stable above 80%. A similar trend is observed with the addition of EDTA, which consistently yields rejection rates above 80%. However, when examining different feed concentrations, the rejection of lithium falls below 80% for leachate concentrates. In summary, satisfactory results are obtained by employing nanofiltration with a TS80 membrane at a pressure of 7 bar, a dilution factor of 10x, and using a 0.02M EDTA complexing agent. Meanwhile, it was found that the separation factors (Li⁺/Ni²⁺ = ~8.6, Li⁺/ Co²⁺ = ~7.3, Li⁺/Al³⁺ = ~4.9) and permeate flux ±46.58 L m⁻² h⁻¹. The findings demonstrate good selectivity along with relatively high flux.

Effect of pH by Manganese Salts and Natural Organic Matter on Nanofiltration Membrane Fouling

This research aimed to determine the removal performance of manganese affected from solution pH of combined manganese salts with natural organic matter (NOM) using commercial nanofiltration (NF) membrane. The filtration experiments were tested under a dead-end filtration test cell. Variational factors used in this study were the types of manganese salts (i.e. manganese chloride (MnCl2), manganese sulfate (MnSO4), and manganese nitrate (Mn(NO3)2)) with the solution pH of 3, 5, and 7, and ionic strength of 0.01 mol/L. Water samples were prepared with NOM concentration of 10 mg/L, while the operating pressure was operated constant at 60 psig. Experimental results found that the MnSO4 salt provided the highest manganese removal efficiency of 95%, while the removal efficiencies of MnCl2 and Mn(NO3)2 were about 84.86% and 70.7%, respectively. Solution fluxes were not significantly different. In the presence of NOM concentration of 10 mg/L, solution pH of 3–7, it was found that low solution pHs for all conditions provided the highest manganese removal. The removals of NOM were relatively high more than 97%. The mathematical fouling model was done with cake filtration model (CFM) due to NOM accumulation on NF membrane surface.

Controlling membrane fouling of nanofiltration using poly-aluminum chloride and Moringa oleifera coagulants

Membrane fouling control during nanofiltration (NF) of contaminated water sources is critical to establishing a cost-efficient advanced drinking water treatment system. This study aimed to evaluate the effect of pre-coagulation using Moringa oleifera (MO) or poly-aluminum chloride (PACl) coagulant on membrane fouling mitigation and final water quality during NF treatment of lake water. This study used four pre-coagulation methods: (i) full coagulation: coagulation-flocculation-sedimentation, (ii) coagulation and flocculation, (iii) rapid mixing alone, and (iv) without coagulant addition. The full coagulation with PACl or MO before NF treatment mitigated membrane fouling, and the optimum PACl or MO coagulant doses achieved the lowest membrane fouling. PACl or MO pre-coagulation with rapid mixing also mitigated membrane fouling, which suggested the potential use of inline coagulation. Turbidity in the coagulated water was the best indicator to predict the level of NF membrane fouling; thus, turbidity in the pre-coagulated water can be utilized to control NF membrane fouling. Regardless of the types of pre-coagulation methods, turbidity and dissolved organic matter concentrations in the NF permeate were equivalent. The results suggest that nanofiltration coupled with inline pre-coagulation can provide high-quality water.

Effect of temperature on organic fouling and cleaning efficiency of nanofiltration membranes for loch water treatment

We investigated the effect of solution temperature on organic fouling and cleaning of polypiperazine nanofiltration (NF) membranes. Fouling experiments were conducted in the temperature range 5 °C ≤ T ≤ 15 °C, characteristic of surface waters in northern latitudes, such as Scottish lochs. Results of laboratory-scale fouling experiments using alginate, a polysaccharide constituent of extracellular polymeric substances, showed a moderate increase in flux loss at 15 °C (41 %) compared to 5 °C (36 %). Analysis of the fouling experiments using a series-resistance model showed that the greater extent of fouling with rising temperature stems from a monotonic increase in water permeance with T. Interfacial property characterisation provided further insight into the effect of temperature on fouling determinants such as membrane hydrophobicity, nanoscale roughness, surface charge, and surface forces. No T-dependence of surface roughness was found. Similarly, we found that water contact angle is invariant within the temperature range investigated, suggesting that the observed fouling behaviour is not due to modulation of hydrophobic interactions. Conversely, colloidal-probe force spectroscopy (CPFS) measurements showed that adhesion forces become stronger with rising temperature. Further analysis showed that repulsive forces – which oppose colloidal particle deposition – become weaker with rising temperature, consistent with fouling trends. Determination of the membrane zeta potential showed that surface charge is invariant over the range of temperatures investigated, suggesting that repulsive forces have a non-electrostatic (likely steric) origin. Additionally, we assessed the effect of temperature on physical and chemical cleaning efficiency, comparing cleaning at the same temperature as the fouling experiments (5 °C ≤ T ≤ 15 °C) with cleaning at 30 °C. We observed that physical cleaning, consisting of water circulation over the fouled membrane surface, is insufficient to remove the foulant layers. On the other hand, chemical cleaning is able to restore 95 % of the original membrane permeance at 10 °C, but only 74 % at 5 °C.

Tuning nanofiltration membrane performance: OH–MoS2 nanosheet engineering and divalent cation influence on fouling and organic removal

Natural organic matter (NOM) present in surface water causes severe organic fouling of nanofiltration (NF) membranes employed for the production of potable water. Calcium (Ca2+) and magnesium (Mg2+) are alkaline earth metals present in natural surface water and severely exacerbate organic fouling owing to their ability to cause charge neutralization, complexation, and bridging of NOM and the membrane surface. Hence, it is of practical significance to engineer membranes with properties suitable for addressing organic fouling in the presence of these cations. This study employed OH-functionalized molybdenum disulphide (OH–MoS2) nanosheets as nanofillers via the interfacial polymerization reaction to engineer NF membranes for enhanced removal of NOM and fouling mitigation performance. At an optimized concentration of 0.010 wt.% of OH–MoS2 nanosheet, the membrane was endowed with higher hydrophilicity, negative charge and rougher membrane morphology which enhanced the pure water permeance by 46.33% from 11.2 to 16.39 L m−2 h−1 bar−1 while bridging the trade-off between permeance and salt selectivity. The fouling performance was evaluated using humic acid (HA) and sodium alginate (SA), which represent the hydrophobic and hydrophilic components of NOM in the presence of 0, 0.5, and 1 mM Ca2+ and Mg2+, respectively, and the performance was benchmarked with control and commercial membranes. The modified membrane exhibited normalized fluxes of 95.09% and 93.26% for HA and SA, respectively, at the end of the 6 h filtration experiments, compared to the control membrane at 89.71% and 74.25%, respectively. This study also revealed that Ca2+ has a more detrimental effect than Mg2+ on organic fouling and NOM removal. The engineered membrane outperformed the commercial and the pristine membranes during fouling tests in the presence of 1 mM Ca2+ and Mg2+ in the feed solution. In summary, this study has shown that incorporating OH–MoS2 nanosheets into membranes is a promising strategy for producing potable water from alternative water sources with high salt and NOM contents.

Thermodynamic mechanism insights into the dynamic evolution of nanofiltration membrane fouling: Effect of calcium ion on organic fouling

To better control nanofiltration (NF) membrane fouling during mine water treatment, an accurate elaboration of the fouling mechanisms of anionic polyacrylamide (APAM) coexisted with Ca2+ and fulvic acid (FA) is vital. An attractive phenomenon was observed during the membrane fouling tests: When Ca2+ and FA coexist with APAM, increasing Ca2+ concentration at high Ca2+ concentration will alleviate membrane fouling. The degree of membrane fouling is determined by the interaction of the foulant with the membrane and is closely related to the Lewis acid-base (AB) interaction energy. At the shortest separation distance, the AB interaction energy decreased from 3608 kT to −17,386 kT when the Ca2+ concentration was increased from 0 mM to 2 mM, then increased to −14,385 kT when the Ca2+ concentration was further increased to 6 mM. The change in AB interaction energy explains the dynamic evolution of the membrane fouling phenomenon. This work elucidates the effects of high Ca2+ concentrations on organic fouling and will benefit the better understanding of the efficient NF processes when multiple pollutants coexist.

Enhanced membrane fouling by microplastics during nanofiltration of secondary effluent considering secretion, interaction and deposition of extracellular polymeric substances

Microplastic (MP) has been found to influence membrane fouling during microfiltration/ultrafiltration processes in direct and indirect ways by acting as fouling components and changing microbial activities, respectively. However, there is no relevant research about the contribution of MPs to nanofiltration membrane fouling. In this study, for the first time, the impacts of MPs on membrane fouling during the nanofiltration of secondary effluent (SE) were systematically investigated from the perspective of bacterial extracellular polymeric substances (EPS) secretion, their interaction with coexisting pollutants and also deposition. Membrane flux behaviors indicate that MPs simultaneously aggravated the short-term and long-term membrane fouling resistance of nanofiltration by 46 % and 27 %, respectively. ATR-FTIR, XPS and spectrophotometry spectra demonstrate that the deteriorated membrane fouling by MPs directly resulted from the increased accumulation of protein-like, polysaccharides-like and humic-like substances on membranes. EEM spectra further confirmed that MPs preferred to induce serious cake layers, which dominated membrane flux decline but hindered pore fouling. According to CLSM and SEM-EDS mappings, MPs in SE could stimulate microbial activities and then aggravate EPS secretion, after which their interaction with Ca2+ was also enhanced in bulk solution. The cross-linker nets could promote the deposition of other unlinked pollutants on membranes. Besides, MPs could weaken the rejection of certain dissolved organic matters (from 57 % to 52 % on the 50th day of filtration) by aggravating cake-enhanced concentration polarization (CECP), but improved the average removal of inorganic salts from 58 % to 63 % by improving their back diffusion through cake layers. Based on these analyses, the mechanisms of MP-enhanced membrane fouling during the nanofiltration of SE can be thoroughly revealed.

Revelation of the interaction between aluminum coagulants and natural organic matters in the dual-system during nanofiltration membrane scaling

Aluminum (Al) coagulants are widely and frequently applied to coagulation pretreatment before nanofiltration. However, the excess coagulants and residual natural organic matters (NOMs) might affect the gypsum scaling during nanofiltration process. This study investigated the nanofiltration membrane fouling process under Al coagulants and specific NOMs, including humic acids (HA), bovine serum protein (BSA), and sodium alginate (SA) in a dual-system. The flux and the particle size decreased significantly when both above were present. The gypsum crystallization on the membrane surface was enhanced, while the bulk crystallization was weakened. Zeta potential and the NICA-Donnan model showed that Al coagulants competed with Ca2+ to bind HA weakening the bulk crystallization of gypsum. Meanwhile, Al coagulants decreased the salt rejection rate. Interestingly, the BSA and SA alleviated the flux decrease. Furthermore, the characterization of the fouled membrane showed that the concentration of Ca2+ and SO42− on the membrane surface increased further in the presence of Al coagulants, the grain size reached 582.0 nm when both HA and Al were present, larger than the control group and when they were present in the feed solution alone. Finally, the modified Hermia model was introduced to analyze the mechanism of the interaction between Al coagulants and NOMs. It is suggested that the control of Al coagulants and HA is necessary for the coagulation pretreatment before nanofiltration.

Efficient removal of perfluorinated compounds with the polyamide nanofiltration membrane and membrane fouling resistance analysis

Abstract Perfluorinated compounds (PFCs) are significant pollutants known for their high toxicity and resistance to natural degradation, posing a severe threat to both the global environment and human health. In this study, a polyamide (PA) membrane with an intermediate layer structure of MXene-TiO2 (referred to as MXT-NFM) was utilized for the removal of PFCs. Experimental results confirm that MXT-NFM exhibited remarkable capacity in intercepting PFCs, accompanied by the high water flux. To gain insights into the mechanisms governing membrane fouling induced by PFCs, inorganic ions, and organics, a series of fouling tests were conducted using MXT-NFM under diverse conditions. Additionally, the XDLVO theory was employed to provide a theoretical perspective on the interactions occurring during the fouling process. The findings suggest that the MXene-TiO2 intermediate layer contributed to the exceptional hydrophilicity and rough surface properties, enabling multiple functionalities. These include alleviating membrane pore plugging, improving the physical configuration of the PA layer, and effectively mitigating fouling phenomena in coexisting systems during practical applications. Moreover, the particle size of pollutant colloids and the acid–base interaction were identified as decisive factors influencing the development of membrane fouling.

Osmotic cleaning to control inorganic fouling of nanofiltration membrane for seawater desalination

The inorganic fouling of NF membrane caused by long-term operation as a pretreatment process seawater desalination cannot be ignored. In this study, an osmotic cleaning with NaCl solution was proposed for controlling NF membrane inorganic fouling in seawater desalination. The effects of cleaning solution concentration, cleaning time and cross-flow velocity of cleaning solution were investigated in this study and the results showed that the cleaning efficiency increased with the cleaning time, the cleaning solution concentration, and the cross-flow velocity of cleaning solution. The water flux of NF membrane for synthetic seawater filtration was recovered to 99.8% of the initial water flux after 5 min of osmotic cleaning with 17 wt% NaCl solution at 0.69 m·s-1 of cross-flow velocity and 25 oC, and reached to 100.0% after 10 min of cleaning. The repeated fouling and cleaning experiment indicated that osmotic cleaning shows high efficiency and long-term stable performance of water flux recovery. The microstructure analysis indicated that CaSO4 and CaCO3 deposited on the membrane surface were efficiently removed, and the main mechanism is that the backwash flux creates synergy effect with ion-exchange to removes the inorganic fouling on the membrane surface. By comparing the changes in water flux and permeate water quality after cleaning with different cleaning methods, it was found that osmotic cleaning has better cleaning efficiency and less membrane damage. The results indicated that the osmotic cleaning is a process combines with dissolution, backwashing and tangential scouring and shows highly efficient performance to control inorganic fouling on NF membrane.

Inorganic and Organic Silicon Fouling of Nanofiltration Membranes during Pilot-Scale Direct Potable Reuse

Inorganic and Organic Silicon Fouling of Nanofiltration Membranes during Pilot-Scale Direct Potable Reuse

Evaluation of Membrane Fouling Control for Brackish Water Treatment Using a Modified Polyamide Composite Nanofiltration Membrane.

In northwest China, the limited amount of water resources are classified mostly as brackish water. Nanofiltration is a widely applied desalination technology used for brackish water treatment; however, membrane fouling restricts its application. Herein, we modified the membrane with triethanolamine (TEOA) and optimized the operating conditions (transmembrane pressure, temperature, and crossflow velocity) to control the nanofiltration membrane fouling by brackish water. Based on the physiochemical characteristics and desalination performance of the prepared membranes, the membrane modified with 2% TEOA (MPCM2) was identified as the optimal membrane, and 0.5 MPa, 25 °C, and 7 cm/s were identified as the optimal operating conditions through a series of nanofiltration experiments. Moreover, the membrane cleaning procedure for fouled MPCM2 was further determined, and a two-step cleaning procedure using ethylene diamine tetraacetic acid disodium followed by HCl with a permeance recovery rate of 98.77% was identified as the optimal cleaning procedure. Furthermore, the characterizations of the fouled and cleaned MPCM2 showed that the optimized cleaning procedure could recover the properties of MPCM2 to near virgin. This study is of great significance for the long-term stable operation of nanofiltration processes in brackish water treatment to ensure the supply of healthy water in the water-deficient areas of northwest China.

Effect of chemical cleaning on nanofiltration process in treating surface water

Nanofiltration (NF) has been increasingly used in drinking water treatment plants; however, the severe membrane fouling caused by organic matter poses great challenges to the application of NF technology. This study investigated the mitigation of NF membrane fouling by different chemical cleaning reagents (e.g., citric acid, NaOH, Na4-EDTA, and Na-SDS), Na4-EDTA and Na-SDS performed better to achieve NF permeability recovery of up to 90.5–94.2 % just in a single chemical cleaning cycle. The hydraulic irreversible membrane fouling could be reduced by 44.9–53.8 % in the multi-cycle operation of chemical cleaning. Na4-EDTA-based cleaning was beneficial to the removal performance of sulfamethazine (SM2) and conferred higher removal efficiency than Na-SDS-based cleaning efficiency. The impact of chemical cleaning on energy consumption was evaluated and indicated that Na4-EDTA-based cleaning could reduce the proportion of unfavorable energy consumption by 4.54 %. The operation stability of the NF process could be effectively improved by chemical cleaning, and the organic pollutants accumulated on the membrane surface can be removed, especially the chemical cleaning using Na4-EDTA and Na-SDS. These findings could improve the operational efficiency of the NF process with low energy consumption, low chemical consumption, and less adverse environmental impact.

Insights into the properties of surface waters and their associated nanofiltration membrane fouling: The importance of biopolymers and high molecular weight humics

Nanofiltration (NF) membrane fouling by surface waters is still an unclear and unpredictable topic due to the heterogeneity and variability of natural organic matter (NOM) in waters. The objective of this study was to identify the key water quality parameter/s responsible for NF membrane fouling. Six representative surface waters were systematically investigated in terms of the water quality characteristics and their fouling potential on a polyamide NF membrane. The results showed that these waters exhibited significant discrepancies in DOC, Ca2+, composition, and chemical characteristics of NOM. Removal performance and membrane fouling analysis indicated a preferential rejection of hydrophobic over hydrophilic NOM, and the hydrophobicity of NOM was positively correlated with reversible fouling. The biopolymer content exhibited a strong positive correlation to the total membrane fouling and irreversible fouling, indicating that it could be used as a surrogate of NF fouling behaviors by surface waters. Ca2+ and humic substances contents could not explain the membrane fouling due to their insignificant correlation with membrane fouling. However, the proportion of high molecular weight component in humic substances (%-HMW) exhibited a negative correlation with the total membrane fouling and irreversible fouling, suggesting that the HMW component has a positive effect on NF membrane fouling prevention. A reasonable explanation is that the HMW component is preferentially deposited on the membrane surface, forming a ‘controlling layer’ that prevents low MW organics from entering and blocking the membrane pores.

Identifying key residual aluminum species responsible for aggravation of nanofiltration membrane fouling in drinking water treatment

Residual aluminum has been identified as one of the key foulants responsible for nanofiltration (NF) membrane fouling in drinking water treatment. However, the extent to which each species of residual aluminum contributes to membrane fouling and the underlying mechanisms are not yet clear. In this study, various pretreatments were applied to a lake water, which generated feed waters of different residual aluminum and species distribution. It was found that Ala (monomeric and oligomeric aluminum species) were mainly in the form of complexes (Ala-NOM) with natural organic matter (NOM), with proportions greater than 70%. The membrane fouling experiments showed that NF operation was sensitive to the presence of Ala, in which a small increase in the Ala concentration of the order of tens of μg/L could greatly aggravate membrane fouling. In contrast, Alb and Alc (intermediately and highly polymeric aluminum species) did not contribute substantially to the membrane fouling process. The membrane fouling potential of Ala increased with increasing coexisting NOM concentration. Results showed that Ala and NOM have a synergistic relationship during membrane fouling. More rigorously, Ala-NOM, rather than Ala itself, are therefore the key residual aluminum species that aggravate NF membrane fouling. The Ala produced by polyaluminum chloride (PACl) had a higher membrane fouling potential than that produced by AlCl3, which was due to the lower polymerization degree of Ala and the more stable complexes with NOM formed when PACl was used. Use of AlCl3 as a coagulant would therefore mitigate NF membrane fouling caused by residual aluminum.

In-situ formation of epoxy derived polyethylene glycol crosslinking network on polyamide nanofiltration membrane with enhanced antifouling performance

Nanofiltration (NF) membrane fouling is still an inevitable main challenge, which leads to the reduction of membrane performance. The large number of aliphatic chains in the poly (vinyl alcohol) (PVA) skeleton will reduce the increase in hydrophilicity. Therefore, the existing PVA grafting technology has certain limitations in the application of anti-fouling modification. A facile and effective strategy for enhancing membrane surface hydrophilicity and antifouling performance becomes very important. In this study, epoxy derived polyethylene glycol crosslinking network was in situ introduced on polyamide nanofiltration membrane through ring-opening reaction of poly(ethylene glycol) diglycidyl ether (PEGDGE) to enhance membrane hydrophilicity and antifouling performance. The large amount of ether units in PEGDGE endowed this crosslinked network with hydrophilicity and relative loose structure. Results of FTIR, XPS and WCA indicated that PEGDGE-polyether crosslinking network was successfully formed on the surface of the NF membrane. Water contact angle of the modified membrane was decreased to 23.7 ± 1.2° compared with pristine NF membrane (45.7 ± 2.1°). For the performance test, humic acid (HA) was used to evaluate the fouling resistance of membranes. FRR (Flux Recovery Ratio) value was as high as 91% (e.g., NF–10 S membrane) compared with the pristine membrane (71%). Meanwhile, NF–10 S membrane showed lower FDR (Flux Decline Ratio) (41%) than the pristine NF membrane (68%). Both the low FDR and high FRR of NF–10 S membranes indicated an excellent long-term anti-fouling property. The coating can provide a large number of ether bonds to improve hydrophilic properties, and the proposed strategy in the current study can offer a facile and effective method for membrane antifouling modifications.

Reducing fouling of an industrial multi-stage nanofiltration membrane based on process control: A novel shutdown system

Here, a new shutdown control system for the nanofiltration (NF) process is proposed to alleviate flushing due to reverse flow caused by the osmotic pressure. The non-reverse flow shutdown control of the multi-stage NF membrane can be achieved through the following steps: (1) refluxing the product water to replace the inlet water; (2) maintaining the high-pressure pump at a constant pressure; (3) sequentially closing the boost pump and the supporting valve; (4) closing the high-pressure pump and the control valve; (5) closing the flushing pump and the control valve. This novel control system was applied to an industrial NF membrane separation system with zero liquid discharge at the Shaanxi Yanchang Coal Yulin Energy and Chemical Co. Ltd., China, and exhibited high stability. Compared with the traditional control strategy, the cost of water treatment was reduced by 0.0029 $/m3, and the produced water increased by 1180 m3 per year for a feed rate of 50 m3/h. The reported methodology, which can improve the long-term process stability and extend the membrane life, shows great potential toward implementation in full-scale NF applications.

Nanofiltration membrane fabrication by the introduction of polyhedral oligomeric silsesquioxane nanoparticles: Feasibility evaluation and the mechanisms for breaking “trade-off” effect

To break the “trade-off” effect and alleviate fouling of nanofiltration (NF) membranes, a variety of polyhedral oligomeric silsesquioxane (POSS) nanomaterials with different functional groups were selected to modify the selective layer. The feasibility of POSS-modified membranes and their performance have been comprehensively evaluated. Compared to the hydrophobic POSS, the water-soluble POSS endowed the NF membranes with enhanced permeability and selectivity owing to the hydrophilic groups and the excellent diffusion in the aqueous solution. Furthermore, the octylamino-POSS was effectively activated by triethylamine, generating more amino groups and participating in the IP process, and providing effective routes to sieve water and Na2SO4. The resultant membrane, i.e., OPN(II) membrane, presented significantly better performance than the pristine PA membrane, both in water flux (90 L/m2h vs. 58 L/m2h) and rejection of Na2SO4 (98% vs. 91%). This OPN(II) membrane also showed consistently higher rejections for all tested salts and recalcitrant organics, accompanying with the improved stability and antifouling capability. Its flux recovery ratio reached up to 85.0%, higher than that of the PA membrane of 79.2%. This work has provided a facile method to prepare thin film composite membrane with enhanced performance, thereby outlining a new way to break the “trade-off” effect of NF membranes.

An efficient system of aerogel adsorbent combined with membranes for reuse of shale gas wastewater

The internal reuse of shale gas flowback and produced water (SGFPW) can ease the pressure on treatment and management costs and freshwater supply. Internal reuse of SGFPW based on membrane treatments is faced with major challenges of the divalent ion and organic pollutant removal as well as membrane fouling control. To solve these problems, a green and efficient adsorbent of porous biochar aerogel (PBA) was combined with ultrafiltration (UF)-nanofiltration (NF) for SGFPW internal reuse in this study. The removal performance of dissolved organic carbon (DOC, >85.9%) and divalent ions (>70.6%) for three SGFPW showed feasibility of PBA-UF-NF process for internal reuse. Three-dimensional excitation-emission matrix (3D EEM) fluorescence spectrum, organic fractionation and the extended Derjaguin-Landau-Verwey-Overbeek (XDLVO) theory were used to identify the organic composition of SGFPW and analyze membrane fouling. PBA tended to adsorb hydrophobic fraction and alleviated UF membrane fouling caused by attractive hydrophobicity. NF membrane fouling was mitigated due to the increased polar repulsion as well as the decreased synergistic fouling between organics and divalent cations through the reduction of DOC by PBA. PBA-UF-NF process had good performance on organic pollutant and divalent ion removal with decreasing membrane fouling, presenting potential to treat SGFPW onsite for internal reuse.

Identifying Key Residual Aluminum Species Responsible for Aggravation of Nanofiltration Membrane Fouling

Identifying Key Residual Aluminum Species Responsible for Aggravation of Nanofiltration Membrane Fouling