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Fabricating crystalline covalent organic framework (COF) membrane with sub-nanopores for desalination remains challenging. Monomer (p -phenylenediamine (Pa) and 1,3,5-triformylphloroglucinol (Tp)) concentration was crucial to tailor the diffusion-reaction process in the p-toluenesulfonic acid (PTSA)-mediated interfacial catalytic polymerization process for crystalline TpPa-COF membrane fabrication. By increasing monomer concentration, membrane surface color evolved from light yellow to dark orange. TpPa-COF layers with adjustable thickness (90.47–436 nm) transformed from amorphous to crystalline with crystalline and cross-linking degree increasing from 16.47 % to 73.90 %, and 66.40 % to 87.60 %, respectively. Pore size decreased from 1.69 to 0.17 nm, while Na 2 SO 4 rejection significantly increased from 26.7 % to 90.4 %. A 3-day filtration test for RO concentrate demonstrated the stability and robust desalination performance with SO 4 2− rejection ratio of 74.3 ± 1.08 % and Mg2+ rejection ratio of 65.6 ± 1.33 %. Diffusion behavior experiments demonstrated that diffusion coefficient for Pa-PTSA complex (6.49 × 10−5–8.87 × 10−5 cm2 s−1, Pa > 0.05 wt%) higher than Tp (3.53 × 10−6–6.39 × 10−6 cm2 s−1, Tp > 0.006 wt%) by one order of magnitude promoted structural crystallinity and regulated assembly at the interface, resulting in TpPa-COF layer with sub-nanopores. This study highlighted the importance of monomer concentration on the COF membrane formation, providing valuable insights for the highly crystalline COF membrane fabrication. [Display omitted] • Highlighting the importance of monomer concentration on the morphology, structure, and performance of COF membranes. • High monomer concentration facilitated structural crystallinity and the formation of sub-nanometer pores. • One-order-of-magnitude difference in monomer diffusivity ensured dense and crystalline COF layer formation. • Optimal membranes exhibited superior stability and desalination for industrial wastewater. [ABSTRACT FROM AUTHOR]

Currently, tungsten mining procedures discharge a large amount of alkali wastewater, necessitating the development of sustainable approaches to valorise valuable bases for further utilization. In this study, diffusion dialysis (DD) and selective electrodialysis (SED) were utilized to recycle the alkali from a simulated tungsten leaching solution; the recycling base was further subjected to anion-exchange membrane water electrolysis (AEMWE) for H 2 production. The results indicate that DD is capable of recycling 0.447 mol/L NaOH base with negligible leakage of WO 4 2−, while the SED process enables the recycling of 1.63–2.01 mol/L NaOH but contains 0.11–0.14 mol/L WO 4 2−. The AEMWE experiment showed that the water electrolyser with SED recycling alkali had a current density of 580.26 mA·cm−2 at 1.8 V, which is much greater than 374.16 mA·cm−2 with DD treatment solution and 352.81 mA·cm−2 without any treatment. The WO 4 2− impurities could adsorb on the surface of the catalyst, which further occupied the catalytic active site of the electrode catalyst and reduced the active specific surface area of the catalyst. This work demonstrated the ability of the SED and DD approaches to recycle alkali for hydrogen production, creating a new pathway for the valorisation of alkali from the tungsten mining industry. [Display omitted] • DD and SED are used for industrial waste alkali recovery. • The recovered alkali is used in the AEMWE process. • The leakage of WO 4 2− in the recovered alkali obtained by DD is negligible. • The SED recovered alkali exhibited the best water electrolysis performance. • WO 4 2− adsorption reduces the effective area of the catalyst and decreases the AEMWE performance. [ABSTRACT FROM AUTHOR]

In recent years, the electrodialysis (ED) technology has gained substantial attention for its role in recovering sulfuric acid from industrial wastewater. However, the typical anion exchange membranes (AEMs) have been known to exhibit notable proton leakage during ED, which can severely hinder the efficiency of acid concentration. To overcome this issue, we utilized a substrate made of poly(vinylidene fluoride-hexafluoropropylene) (PVDF-HFP). This choice capitalizes on the presence of fluorine-containing groups for enhanced acid stability and tertiary amine groups to minimize water content, resulting in a significant improvement in proton-blocking capabilities of the AEMs. It is worth noting that, through a combination of partial cross-linking and quaternization, these AEMs not only maintain their acid concentration performance but also substantially reduce energy consumption. Additionally, we conducted a thorough analysis of the delicate balance between current efficiency and energy consumption in acid recovery systems. In contrast to conventional AEMs and commercially available proton-blocking membranes such as ACM, we highlight the exceptional acid concentration capability (C H + = 1.28 M) and the low energy consumption (3.3 kWh/kg) of AEM-1.2. This research breakthrough marks a significant advancement in the development of acid-blocking AEMs and strongly advocates for more efficient sulfuric acid recovery from industrial wastewater. [Display omitted] • A series of acid-blocking AEMs based on PVDF-HFP has been prepared. • The as-prepared AEM was partially quaternized to reduce energy consumption. • The final concentration of AEM prepared is better than that of commercial AEM. • The problem of poor acid enrichment performance of traditional AEMs was solved. [ABSTRACT FROM AUTHOR]

The key to achieve sustainable treatment of high-salinity dye-containing wastewater is effective fractionation of dyes and salts. In this study, a thin-film composite electro-nanofiltration membrane was successfully fabricated by co -deposition of levodopa and ε-polylysine onto a porous ultrafiltration membrane substrate. With the co -deposition of the polylevodopa/ε-polylysine composite coating on the substrate membrane, the surface properties were significantly regulated, resulting in decreased pore size, reduced surface negative charge density and lower specific electric resistance, thus enhancing their ion transfer and dye/salt fractionation efficacy. Specifically, the fabricated LDP-4 membrane (molecular weight cut-off of 408 Da) with a 4-h co-deposition experienced a 99.12 % reactive orange 16 dye rejection and 10.15 % NaCl rejection, indicating an impressive selectivity between dyes and salts. Additionally, the LDP-4 electro-nanofiltration membrane as anion conducting membrane exhibited a fast and efficient electro-driven transfer of Cl− ions. Notably, under an electric field, the fabricated LDP-4 electro-nanofiltration membrane can efficiently fractionate NaCl from the reactive orange 16/NaCl mixed solution, achieving a 98.89 % desalination efficiency and 99.79 % dye recovery. Furthermore, the LDP-4 membrane demonstrated remarkable anti-fouling property and long-term stability over an 8-cycle electro-nanofiltration operation. Therefore, the electro-nanofiltration membranes fabricated by co -deposition of levodopa and ε-polylysine show a promising potential in sustainable resource recovery from high-salinity dye-containing wastewater. [ABSTRACT FROM AUTHOR]

Graphene oxide-based loose nanofiltration membranes have shown significant potential in nanofiltration processes due to their unique 2D mass transfer nanochannels. However, they still suffer from poor structural stability and overly compact laminar stacking. To address these issues, a novel AP-POSS was intercalated into GO-based membrane to construct a tuned interlayer structure and mass transfer characteristics. The aromatic ring structure of aminophenyl groups on AP-POSS act as hydrophobic side walls of the mass transfer channels between adjacent GO nanosheets, reducing the interaction between water molecules and channel structure. With an optimal amount of AP-POSS as an intercalator, the permeation flux of the prepared POSS-GO membrane could be improved by 30 wt% while maintaining nearly complete rejection of Congo Red (CR). Moreover, the prepared membrane exhibited enhanced structural stability, long-term stability, and a separation factor above 91.0 for CR/NaCl in binary solutions. Our study highlights the excellent performance of the POSS-GO membrane and demonstrates its potential application in dye/salt wastewater treatment. [Display omitted] [ABSTRACT FROM AUTHOR]

In dye/salt separation of textile industry wastewater, bio-fouling holds negative effects on separation ability of loose nanofiltration (LNF) membrane. A novel ultra-high in-situ anti-bacterial LNF membrane was firstly fabricated through interfacial polymerization (IP) using a synthetic aqueous monomer of 1,2-bis (N -aminoethyl imidazoline) ethane (BAIE) and a commercial organic monomer of 1,3,5-tris(bromomethyl)benzene (TBB) in this work. Notably, the BAIE-TBB LNF membrane containing anti-bacterial imidazole structures by IP process could prevent the loss of anti-bacterial modifiers and keep the imidazole structures loaded meanly. It showed significant anti-bacterial performance for Escherichia coli and Staphylococcus aureus. Moreover, the fabricated BAIE-TBB LNF membrane with 0.1 wt% TBB (M-0.1) exhibited an ultra-high water permeance of 157.1 LMH/bar, a high Congo Red (CR, 100 ppm) rejection of 99.6 %, and a low NaCl (1000 ppm) rejection of 1.5 %, due to its relatively loose functional layer. For the salt/dye mixed solution, M-0.1 presented excellent separation performance with a CR/NaCl separation factor (α 246.3), and still exhibited good salt/dye separation performance under high salt concentration. With excellent water permeability, dye/salt separation, and anti-bacterial properties, BAIE-TBB LNF membrane holds great application potential in dye/salt separation. [Display omitted] • A novel BAIE-TBB LNF membrane was designed with in-situ anti-bacterial structure. • BAIE-TBB LNF membrane exhibited an ultra-high pure water permeance of 157.1 LMH/bar. • BAIE-TBB LNF membrane displayed excellent in-situ anti-bacterial performance. • BAIE-TBB LNF membrane exhibited efficient dye/salt separation. [ABSTRACT FROM AUTHOR]

Effective organic dyes selective separation from high salinity textile wastewater consisting of inorganic salts and organic dyes is of great significant for the textile wastewater treatment. Graphene oxide (GO) have been used widely to form ultrathin high-permeance membrane for molecular and ionic sieving. However, swelling and membrane fouling of GO membrane hampered its practical applications. In this work, high stability and antifouling reduced graphene oxide (rGO) membranes were prepared, and Fe 2 O 3 nanoparticles was used as intercalation to turn the membrane interlayer spacing. The rGO/2Fe 2 O 3 nanocomposite blended membrane exhibited high permeance of 24.90 L m−2 h−1 bar−1, excellent organic dyes rejection (98.15 % and 98.69 % for methylene blue and Evans blue, respectively) and low salt retention (6.26 % for NaCl). Meanwhile, this membrane demonstrated a superior selective dye/salt separation factor up to 232 with a high rejection of 99.59 % to Evans blue and a lower salt rejection of 5.03 % to NaCl. Furthermore, nanofiltration experiments towards Evans blue/NaCl mixed solution indicated that the membrane also exhibited excellent antifouling performance with flux recovery rate of >86 % after six fouling/backwash cycles. Therefore, our work may provide a promising idea for the development of two-dimensional nanofiltration membranes for efficient high salinity textile wastewater treatment. Separation mechanism and selective separation performances [Display omitted] • A novel graphene-based membrane was prepared by in-situ intercalating Fe 2 O 3 nanoparticles. • Fe 2 O 3 nanoparticles tune the interlayer spacing and enhance the hydrophilicity of membranes. • The rGO/2Fe 2 O 3 membranes exhibited high permeate flux and excellent selective separation performance. • The rGO/2Fe 2 O 3 membranes demonstrated good long-term stability and excellent antifouling performance. [ABSTRACT FROM AUTHOR]

Zero liquid discharge (ZLD) of industrial wastewater is an important way to achieve the recycling of waste resources. However, the utilization of the concentrated brine or/and waste salt has become one of the crucial bottlenecks restricting the ZLD process. The ion exchange membrane-based chlor-alkali process (termed chlor-alkali membrane cell process) that reuses industrial waste salt as raw material can close the technology gap between the production lines. However, the ZLD waste salt contains numerous and complex impurities, which can cause membrane fouling, posing a new challenge for the chlor-alkali membrane cell process. To this end, this paper systematically reviews the principles and process flow of waste salt utilization in the chlor-alkali membrane cell process. We have delved into the mechanisms, impacts, and characterization methods of ion exchange membrane fouling caused by anions and dissolved organic matter. Moreover, this paper proposes practical strategies encompassing feed pre-treatment, membrane cleaning and modification, and operating condition optimization to address the membrane fouling issues. We have indicated the future research directions in this domain. These efforts aim to foster the development and implementation of waste salt recycling technology within the context of achieving the sustainable management of industrial wastewater. [Display omitted] • Waste salt utilization is crucial for zero liquid discharge of industrial wastewater. • Chlor-alkali membrane cell process is a promising alternative. • Waste salt can cause significant ion exchange membrane fouling. • Fouling mechanisms, impacts and characterization methods are reviewed. • Coping strategies include pre-treatment, cleaning and membrane modification. [ABSTRACT FROM AUTHOR]

In this study, the fouling propensity of a hybrid ceramic membrane bioreactor (CMBR)-reverse osmosis (RO) process was investigated over a prolonged period using real textile wastewater effluent. Additionally, the effectiveness of in-situ ozonation for fouling mitigation was investigated. The results revealed that the CMBR-RO system achieved approximately 99.8 % removal of chemical oxygen demand and 97.4 % removal of total nitrogen. Despite this, soluble extracellular polymeric substances, particularly biopolymers and humics-like substances, remained in the system, resulting in irreversible fouling on the ultrafiltration (UF) membrane. The implementation of in-situ ozonation notably reduced ceramic membrane fouling by enhancing the filterability of larger macromolecules and eliminating inorganic/organic foulants from the membrane surface. Multiple modified fouling indexes were also utilized to evaluate the fouling potential of the RO feed water through size fractionation. It is worth noting that ozonation could pose a potential risk for subsequent RO membrane fouling due to the formation of low molecular weight neutrals, acids, and calcium- or silica- related inorganic-organic complexes. Overall, the integrated CMBR-RO system with in-situ ozonation exhibited excellent performance in producing clean water, achieving nearly 100 % removal of 20 Aromatic Amines. These findings underscore the viability of the CMBR-RO system as a practical and sustainable choice for the reclamation of textile wastewater. [Display omitted] • Biopolymers and humics-like substances led to irreversible fouling • In-situ ozonation significantly improved the filterability of larger macromolecules • LMW molecules induced by ozone poses a potential risk for subsequent RO • The hybrid process removed almost 100% of 20 AAs in final water [ABSTRACT FROM AUTHOR]

Graphene oxide (GO) membrane is considered as one of the preferred choice for textile wastewater treatment thanks to its unique 2D interlayer channel features. However, GO laminar stacking is inclined to water-induced structure instability, and the narrow interlayer spacing limit mass transport efficiency, hampering its effectiveness in water treatment applications. Herein, a layer-by-layer stacked microcomposite membrane based on GO and highly microporous β-cyclodextrin based nanosheets (β-CDNS) served as intercalator was developed. The distinctive layered structure was further stabilized by covalent cross-linking with glutaraldehyde (GA). The microporous β-CDNS offered additional nanochannels that facilitated the rapid penetration of water molecules, while the abundant -OH groups provided sites for chemical cross-linking, enhancing membrane stability. The optimal GO/β-CDNS1 membrane exhibited a superior water permeance of up to 83.5 LMH/bar, with >99 % rejection for dyes such as Congo red (CR), methyl blue (MB), and chrome black T (CBT), 95.5 % for acid fuchsin (AF). Meanwhile, the GO/β-CDNS1 membrane demonstrated ultra-low (<5 %) retention for inorganic salts (MgSO 4 , MgCl 2 and NaCl), with a separation factor as high as 194 for MB/NaCl mixtures. Therefore, employing functional interlayer nano-additives to well regulate the GO interlayer structure offers a promising guideline for developing high-performance GO-based membranes. [Display omitted] • Microporous β-CDNS co-stacking with GO to construct 2D microcomposite membranes • The intercalator enlarged GO interlayer spacing and provided multiple permeation pathways • The membrane displayed a water flux as high as 83.5 LMH/bar and 99.5 % MB rejection. • The membrane showed superior performance for dye/salt separation. • The membrane exhibited superior stability soaking in aqueous solution for 90 days. [ABSTRACT FROM AUTHOR]

In recent times, loose nanofiltration (NF) membranes have gained popularity for the treatment of dye/salt industrial wastewater, primarily owing to their exceptional separation capabilities and economic advantages. However, achieving nanocomposite mixed matrix membranes with ultrahigh water permeance and specific pore and surface characteristics for effective dye and inorganic salt fractionation presents a significant challenge. This study focuses on the development of high-efficiency loose nanofiltration mixed matrix membranes (MMMs) achieved by combining polymers and porous nanoparticles. Metal-organic frameworks (MOFs) hold substantial promise as porous additives in MMMs. However, high-quality MOF-based MMMs for treating dye/salt aqueous solutions are still scarce. In this work, we synthesized an aluminum-based metal-organic framework (CAU-10-H) and utilized it in the fabrication of composite MMMs by blending it with co -polyimide (P84). We successfully created a thin and porous CAU-10-H/P84 layer with a significantly low MOF content (1.5 %) on a nylon support. Our research findings revealed that the optimized membrane exhibited desirable permeance (260.4 LMH/bar) for dye/salt solutions and a pure water permeance of 386.4 LMH/bar. Furthermore, the membrane demonstrated high dye rejection (99.2 % for methyl blue and 99.1 % for Congo red) while maintaining low salt rejection (4.8 % for NaCl and 16.3 % for Na 2 SO 4). Additionally, the composite MMMs exhibited excellent stability throughout a 24-h filtration process. The CAU-10-H/P84 composite MMMs exhibit significant potential for applications in dye/salt fractionation. [Display omitted] • Loose nanofiltration MMM made from CAU-10-H and P84 co -polyimide • The CAU-10-H/P84 MMMs showed improved hydrophilicity and dye rejection. • The CAU-10-H/P84 MMMs exhibited good antifouling and long-term stability. [ABSTRACT FROM AUTHOR]

Freezing desalination can produce freshwater from seawater or industrial wastewater by ice crystallization with low energy consumption and less corrosion, and is promising for alleviating current stress on the world's water supply. However, the salt rejection dynamics during the freezing process is less understood due to the lack of real-time, high spatiotemporal-resolved detection methods. Here we present a proof-of-principle, quantitative, and simultaneous multi-salt detection approach for the measurement of salt rejection dynamics in salt-contaminated water at the ppm level using an ultrashort-pulsed femtosecond laser propagating in the filamentation regime. We show that this approach of filament-induced plasma spectroscopy possesses the abilities for both monitoring the change of salt concentration in the remaining unfrozen water during the freezing process and imaging the spatial concentration distributions of metal contaminants on the resultant ice surface. With this approach, we find that the initial salt concentration in water plays an essential role in the efficiency of the freezing desalination process, which shows a metal-species-dependent characteristic. Our results pave the way towards real-time, online, and high spatiotemporal-resolved detection of salt rejection dynamics of freezing desalination by ultrashort-pulsed lasers. • FIPS spectra of the ice body are measured for the first time. • Spatial concentration distribution of salt on the ice surface is mapped by FIPS. • Potential of FIPS in monitoring freezing desalination (FD) is shown. • Roles of the salt concentration and the ionic species in FD are revealed by FIPS. [ABSTRACT FROM AUTHOR]

The car wash wastewater was separated by ultrafiltration. The commercial ultrafiltration (UF) polyethersulfone (PES) membranes (10 and 100 kDa) were applied. The FTIR analysis indicated that membrane matrix beside PES also contained poly(vinyl pyrrolidone) (PVP). These membranes were used for the wastewater separation, achieving over 50 % rejection of most contaminants and the permeate with a turbidity of <0.2 NTU. It has been shown that a severe membrane fouling was caused not only by the pollutants removed from the cars but also by the detergents used for car washing. As a result, the permeate flux disappeared after 5–10 h of filtration. The Hermia's models analysis indicated that raw wastewater (841 NTU) caused both complete blocking and intermediate fouling mechanism. Wastewater turbidity was reduced by sedimentation (29 NTU), and consequently, cake formation was dominant fouling mechanism in this case. Fouling was reduced by washing the membranes with alkaline agents (pH = 11–12), commonly used in car washes, to clean wheels and remove insects. By washing the membranes every 5–7 h for 30 min with solutions (0.3–0.5 %) of these agents a stable permeate flux at a level of 80 % of the initial flux was obtained during 100 h wastewater filtration tests. [Display omitted] • Ultrafiltration as an effective method of car washes wastewater treatment. • Effluents from car washing caused severe membrane fouling. • Alkaline agents used in the car wash can reduce fouling of the UF membranes. [ABSTRACT FROM AUTHOR]

Although Janus membranes (comprising a hydrophilic antifouling layer on a wetting-resistant membrane substrate) have shown promise in sustainable membrane distillation (MD) processes for treating industrial wastewaters, most fabrication methods are substrate-specific and lack a universal technique for robust Janus MD membranes. Here, we present a non-substrate-specific technique using polydopamine-assisted, surface-initiated atom-transfer radical-polymerization (ATRP) that grafts a zwitterionic polymer layer onto any wetting-resistant substrate. We first prepare a model omniphobic substrate by surface fluorination of a quartz fiber mat, followed by polydopamine-assisted ATRP to complete Janus membrane fabrication. The grafting of zwitterionic polymer layer with a tunable thickness (∼1–10 μm) on one side of the membrane surface, while preserving the omniphobicity of the membrane substrate, is demonstrated. The binding robustness of the two layers of disparate wettability is then shown. An excellent antifouling functionality of the Janus membrane is confirmed by complete oil detachment in a static oil-fouling test, and by the stable desalination with nearly perfect salt rejection (> 99 %) in direct contact MD using a surfactant-stabilized, crude oil-in-brine emulsion, as simulated high-salinity industrial wastewater feed. Finally, we apply our modification technique to other lab-fabricated as well as commercial non-wetting substrates to demonstrate its universal applicability for Janus membrane fabrication. [Display omitted] • We developed a universal technique to fabricate Janus membranes using polydopamine. • The membranes exhibit robust bonding of hydrophilic layer and omniphobic substrate. • The membranes show excellent oil-fouling resistance and stable desalination in MD. • The modification technique is applicable to any non-wetting substrates. [ABSTRACT FROM AUTHOR]

Interfacial solar steam generation (ISSG) is a sustainable and promising technology. Solar energy is used to desalinate seawater and purify industrial wastewater. Solar absorbers based on carbonized biowaste have received increasing attention because they are biocompatible, carbon-rich, hydrophilic, have low thermal conductivity, and exhibit excellent solar absorption. We fabricated a three-dimensional (3D) photothermal material based on carbonized orange peel (COP) for ISSG. The microscopic pores of COP ensured excellent thermal insulation, and the upward-concave shape enhanced light absorption and the self-floating capacity. COP exhibited an evaporation rate of 1.86 kg m−2 h−1 and energy efficiency of 87.90 % under 1 sun irradiation. Additionally, the salt rejection rate was 99.99 % during desalination, and the dye removal rate was 100 % during water purification. Our solar evaporator is thus a low-cost and efficient means of ISSG, and it shows that biowastes can serve as effective photothermal materials. 3D self-floating upward concave-shaped COP has been designed by using a freeze-drying method followed by carbonization in the inert atmosphere. 3D self-floating upward concave-shaped evaporator exhibited extremely efficient water evaporation capability due to its unique shape providing large surface area, excellent hydrophilicity, and good solar-to-heat conversion ability. [Display omitted] • A 3D self-floating concave shaped biowaste orange peel-derived evaporator was designed. • The absorber possessed large surface area, excellent hydrophilicity, and good solar-to-heat conversion ability. • COP evaporator exhibited an evaporation rate of 1.86 kg m−2 h−1 and an efficiency of 87.90 % under 1 sun. • The unique design demonstrated 99.99 % salt rejection for desalination and 100 % dye removal for water purification. [ABSTRACT FROM AUTHOR]

One of the major waste streams within the oil and gas (O&G) industry is produced and process water generated during hydrocarbon production and treatment, respectively. In gas production facilities, process water typically has lower salinity (i.e., <10,000 mg/L) which present opportunities for these wastewaters to be treated for beneficial reuse applications via advanced water treatment technologies, such as reverse osmosis (RO) membranes. One of the key challenges for RO membranes application to industrial wastewater treatment is fouling which is frequently attributed to the soluble organics present in the water and/or associated with field chemicals. In this study, a detailed organic characterization methodology, using liquid chromatography with organic carbon detector (LC-OCD) was applied to characterize the organics on a real process water collected from industrial wastewater treatment plant at a gas production facility. Additionally, a rigorous bench-scale testing procedure was implemented to assess the performance of a full-scale RO system with and without activated carbon filter (ACF) pretreatment, making this study the first one to apply LC-OCD methodology on real wastewater to evaluate the fouling of RO membranes deployed at an industrial treatment plant. Bench-scale RO results showed that in the absence of ACF pretreatment, a 12 % decline in membrane permeability (from 1.78 to 1.57 L/(m2-bar-h)) was observed, while no permeability decline was measured after ACF treatment. The organic fouling was confirmed by mass balance calculations on the bench scale experiments as well as Fourier Transform Infrared (FTIR) analysis on the membrane coupons. Moreover, LC-OCD analysis showed that the ACF inlet has a TOC concentration of approximately 3.06 mg/L; of those 1.29 mg/L (42 %) are hydrophobic, and 1.77 mg/L (58 %) are hydrophilic. After ACF treatment, the hydrophobic organics decreased to 0.65 mg/L, revealing that the ACF is removing >50 % of hydrophobic organics which are likely responsible for membrane fouling. Bench-scale operational and water quality results were comparable to the full-scale RO performance data validating the lab testing procedure implemented in this study. [Display omitted] • Evaluated organics impact on RO fouling with and without pretreatment. • Activated carbon treatment reduces hydrophobic organics from 1.3 to 0.65 mg/L (50 %). • Without ACF pretreatment, 12 % RO fouling was observed & attributed to organics. • After ACF treatment, no RO flux decline was observed. • Bench-scale operation and water quality data were comparable to full-scale RO plant. [ABSTRACT FROM AUTHOR]

This experimental study aims to improve the performance of a tubular solar still using enhanced thermal management methods. Paraffin wax with a melting point of 44 °C is used as a phase change material (PCM). Three main methods of improving solar still desalination performance were analyzed including pure PCM, nano-enhanced PCM with Co 3 O 4 , and the combination of nano-enhanced PCM with aluminum shavings, and compared to a conventional tubular solar still. In order to improve the thermal performance of the portable desalination design, copper tubes containing industrial metal waste, as the porous media, and baffles coated with micro Al 2 O 3 -black paint were utilized in the solar still basin. The addition of 0.3 % Co 3 O 4 nanoparticles along with aluminum shavings led to improve the thermal properties of paraffin wax by reducing >50 min in the melting time. Based on the obtained results, the enhancement in cumulative productivity reached 5.69 %, 15.30 %, and 24.56 % for these three scenarios compared to the conventional solar still with a cuboid basin, respectively. Also, the average efficiency improved from 41 % to about 46.7 %, 51.2 %, and 64.3 %, respectively. Furthermore, the measured total dissolved solids (TDS) of the distilled water in all scenarios was within an acceptable range. • A tublar solar still was designed and experimentally prepared for water desalination. • Phase change material, enhanced with nano-Co 3 O 4 and Al shavings, was investigated. • Cumulative productivity enhanced by 24.56 %, compared to a conventional solar still. • Average efficiency reached 64.3 % for the solar still with nano-enhanced PCM and Al. • Applying enhanced PCM and porous media led to a melting time reduction of >50 min. [ABSTRACT FROM AUTHOR]

Neodymium‑iron‑boron (NdFeB) scraps contained 20–30 % rare earth elements such as neodymium, iron, boron, dysprosium, and praseodymium, which are valuable untapped rare earth resource. Hydrometallurgical extraction through hydrochloric acid treatment is often used to separate the rare earth metals and impurities in the NdFeB scraps, resulting in large amounts of acidic lixiviate and high-salinity brine, challenging to further treatment and detrimental to the environment if directly discarded. In this work, direct contact membrane distillation (DCMD) was explored to treat NdFeB scraps precipitation wastewater (NPW) by testing systematically three different hydrophobic commercial membranes. The impact of the membrane surface properties on the recovery performance and membrane scaling were investigated. The results showed that the membranes with strong hydrophobic properties and smaller pore size distributions possessed greater anti-scaling potential compared to the other materials. Additionally, the membranes with greater porosity offered longer stable operation at high flux, with the PTFE-0.22 membrane maintaining a flux over 20 kg/m2·h for up to 8 h. Membrane scaling caused by calcium carbonate during DCMD treatment was significantly mitigated by systematic chemical cleaning and after four cycles of testing, >75 % initial flux was restored via a simple acid cleaning. An average of 53.4 g/L sodium chloride with the purity of 99.3 % was obtained from the concentrated NPW by evaporation crystallization. This work demonstrated the potential of DCMD to act as a resource concentration and recovery tool on industrial effluents. [Display omitted] • NPW treated by DCMD achieved near-zero liquid discharge. • Membrane with high porosity provided long-term stability for high flux. • Membrane with strong hydrophobic and smaller pores showed superior resistance to scaling. • Membrane scaling was effectively mitigated by acid cleaning. • Sodium chloride with purity above 99.3 % was recovered from NPW. [ABSTRACT FROM AUTHOR]

Desalination is an energy intensive process requiring adequate pre- and post- treatment. The novelty of this paper is that it jointly reviews the technologies for pre-treatment, desalination and post-treatment and bridges the gap between them while comparing the treatment methods needed depending on the type of feed water including seawater, brackish water, municipal and industrial wastewater. Those different streams show wide variability, sometimes containing organics, oil or scaling precursors which require adequate treatment. Nowadays, membrane pre-treatment methods have become promising alternatives to conventional pre-treatment techniques thanks to their flexibility. Hybrid desalination technologies have shown great potential in reducing energy consumption. Moreover, desalination plants produce large quantities of brines which require post-treatment to reduce environmental impacts. Current research on post-treatment is looking into recovering salts, metals and potable water from brines to achieve zero liquid discharge (ZLD). Thermal-based ZLD technologies are capable of extracting those resources while membrane-based ZLD methods are mostly limited to pre-concentration and water recovery due to fouling issues. Several studies have shown that ZLD systems can lower the cost of water and increase profitability if crystals and water are recovered and sold for additional revenue. • Overview of pretreatment technologies and scrutinize its potential role in the desalination industries. • Potential environmental impact of the waste brines with reference to the zero liquid discharge and their management • Pre and post treatment mapping to support desalination industries. • Explore options in the potential reduction of the environmental damage via zero liquid discharges [ABSTRACT FROM AUTHOR]

The increasing demand for efficient and sustainable solutions in the field of energy storage and water desalination has sparked research in the development of supercapacitors and capacitive deionization (CDI) cells. This study presents a scalable and eco-friendly process for the preparation of N-doped polyhedral macrotube carbon arrays with a multihole cross-sectional profile. These arrays were synthesized from lotus stems (N-ALS) through carbonization at 500 °C and activation at 700 °C. The resulting material offers a high density of adsorption sites and good conductivity, making it suitable for use as electrodes in both supercapacitors and CDI cells. The N-ALS electrodes exhibit a high specific capacitance of 221.34 F g−1 at a scan rate of 2 mV s−1 and excellent cycling stability, as well as a salt adsorption capacity (SAC) of 26.07 mg g−1 at an applied voltage of 1.4 V and 85 % retention after 50 desalination-regeneration cycles in CDI cells, outperforming traditional activated carbon electrodes. • The environmentally friendly, N-doped porous biochars has been successfully prepared through a facile and efficient method. • N-ALS has better electrochemical performance, higher desalination efficiency and good recycling in CDI cells. • This study provides feasibility for the application of CDI in metallurgical wastewater treatment. [ABSTRACT FROM AUTHOR]

Wastewater phosphorus (P) released into natural water bodies such as lakes and rivers, can cause water pollution as a result of eutrophication. If this P is effectively removed from wastewaters and economically recovered for use as fertilisers, not only can the water pollution be controlled, but also reduce the anticipated global shortage of P. This scarcity will result from the natural phosphate rock reserve being exhausted. Three experiments were conducted using membrane-bioreactor effluent (MBR, 35 mg PO 4 /L) and reverse osmosis concentrate (ROC, 10 mg PO 4 /L) waters to supply phosphate, and sea water (1530 mg Mg/L) to supply Mg for the production of struvite. The phosphate in the MBR and ROC was concentrated approximately 15 times by adsorption onto an ion exchange resin column followed by desorption. Struvite was precipitated by mixing the desorbed solution with seawater and NH 4 Cl. The chemical composition and mineral structure of the precipitates agreed with those of the reference struvite. When Ca in seawater (300 mg Ca/L) was removed before mixing the water with MBR or ROC, the purity of the struvite improved. [ABSTRACT FROM AUTHOR]

The rapidly growing electroplating industry has led to the discharge of large amounts of wastewater containing heavy metals. Electrodeposition techniques can recover metals from wastewater, which have economic and environmental benefits. However, the application of electrodeposition involves high energy costs facing actual industrial wastewater. This is closely related to the complex nature of the wastewater, which contains high levels of inorganic and organic impurities, which is significantly inconsistent with the water used in the laboratory simulation. In this study, only a simple adsorption process for pretreatment can remove 76 % of the TOC and reduce the electrical conductivity by 38 %. The electrodeposition could reduce the ineffective energy consumption by 60 %–80 % from 10 kw∙h/kg to 6–7 kw∙h/kg for actual wastewater, compared to the effective energy consumption of 5 kw∙h/kg for simulated wastewater, demonstrating that the adsorption pretreatment had a positive effect on the deposition of Cu. Notably, the results of SEM and optical microscope indicated that a more compact copper texture was obtained after pretreatment, and the findings of EDS and XRD showed that both simulated and actual wastewater yielded high-purity metallic Cu. This work provided an effective way to promote the application of electrodeposition in real wastewater treatment. [Display omitted] • Impurities of actual wastewater make the application of electrodeposition difficult. • Adsorption is an effective method for removing the organic and inorganic matter. • The ineffective energy consumption for electrodeposition was reduced by 60–80 %. • The morphology of copper was more convenient for recovering after pretreatment. [ABSTRACT FROM AUTHOR]

Herein, a novel method is proposed for selectively capturing SO 2 and CO 2 gases using a single absorbent derived from seawater-based industrial wastewater. The method is based on the thermodynamic properties of the absorbent, which produces a driving force for the preferential capture of SO 2 over CO 2 gas due to the difference in Gibbs free energy and formation enthalpy. Once SO 2 and CO 2 were captured in the aqueous medium, they were mineralized into calcium sulfate dihydrate (gypsum) and MgCO 3 , respectively. To enhance the industrial applicability of the final products, the crystallization properties of each precipitate, such as the particle size, crystallinity, polymorph, and purity were investigated at different ion concentrations in the aqueous suspension. The results demonstrated that the crystalline structures of both CaSO 4 and MgCO 3 are highly affected by the ion distribution in the aqueous medium, thus controlling the target structures. A higher saturation level leads to larger particle sizes via stronger agglomeration between crystallites. However, the residual calcium ion concentration inhibits crystal growth during MgCO 3 nucleation; thus, the number of hydrates was controlled for each sample. We hope that this study provides a viable option for the scale-up of the carbon capture utilization and storage technology and an alternative carbon capture technique to address the limitations and viability of currently employed technologies. [Display omitted] • Selective gas absorption utilizing seawater-based industrial wastewater is designed. • The crystallization of gypsum was investigated at different absorbent concentration. • The hydration control of MgCO 3 was observed at different absorbent concentration. • Achievement of a simultaneous reduction in both aquatic and atmospheric pollutants. [ABSTRACT FROM AUTHOR]

A model that can be used to predict the performance of Membrane Capacitive Deionization (MCDI), including current efficiency, flowrate of the product water, water recovery and energy consumption is established in this work. The model was developed using a Response Surface Model approach that considers the influence of influent conductivity, flowrate passing by the electrodes and applied current on MCDI system performance rather than relying on electrochemical principles or the description of the intrinsic properties of the carbon electrodes and ion exchange membranes. In the scenarios tested here, flowrate contributes the most towards MCDI performance. The appropriateness of using NaCl for an MCDI performance model is confirmed. The model can be applied to extensive applications with two examples detailed here including a small town potable application of 100 m3/day with influent water of 2000 μS/cm and an industrial wastewater application of 1000 m3/day with influent water of 4000 μS/cm. A costing model is developed and applied to the two scenarios with the optimised levelized cost of water (LCOW) found to be US$0.74/m3 for the small town and US$1.08/m3 to US$1.41/m3 for the industrial wastewater (product water quality dependent). By maximising the production rate, the LCOW can be minimised. The model presented here can be applied to a wide range of applications or used as a framework for efficient performance modelling of other MCDI configurations. [Display omitted] • A framework for a simplified MCDI performance model developed. • MCDI performance model based on influent conductivity, flowrate and applied current. • Levelized cost of water (LCOW) of US$0.74/m3 for MCDI treated potable supply. • LCOW can be minimised by maximising MCDI production rate. [ABSTRACT FROM AUTHOR]

High-salt wastewater treatment is one of the hot topics in environmental protection industry. Under the requirement of "Zero Liquid Discharge", thermal evaporation is necessary, and it is particularly important to deal with the fouling problem of heat exchangers. This paper describes the fouling mechanism in detail, introduces the traditional and novel antifouling coatings. The low surface energy of the antifouling coating can effectively reduce the thickness of the adhering dirt layers, so that the settlement is reduced and easy to peel off, while also dissolving the organic matter that is difficult to remove. The advantages and disadvantages of various antifouling coatings are summarized and analyzed. This paper aims at providing theoretical support for the antifouling research of high-salt wastewater heat exchangers. [Display omitted] • Fouling mechanism of heat exchangers for high-salt wastewater is explained. • The main influencing factors of the fouling are reviewed. • Active anti-fouling effects of composite anti-fouling coatings are summarized. • Current problems to be solved with anti-fouling coatings are put forward. [ABSTRACT FROM AUTHOR]

The demonstration is specifically designed to achieve the reclaimation of integrated chemical industry park wastewater (CIPWW) with high levels of hardness and salinity and the standardized discharge of concentrates generated during the reclaimation period by effectively composing dual-membrane technology combined by microfiltration (MF) and reverse-osmosis (RO) with multiple water treatment techniques. Concerning the concentrates generated by RO, the full-scale calcium-sulfate (CaSO 4) crystallizer is creatively applied as the pretreatment unit for hardness removal with doubled catalytic ozonation-high performance biological aerated filter (O 3 -HBAF) and ultrafiltration (UF) as subsequent treatment technologies. Considering the characteristics of RO concentrates as high permanent hardness, high sulfate concentration and high refractory organic matter (ROM) content, pilot tests were conducted particularly focusing on the CaSO 4 crystallizer and O 3 -HBAF unit which verified the reasonability of the technological process, and relevant operating parameters were optimized including flocculant dosage, catalyst dosage, etc. A series of adjustments were also made for the agent-addition devices of RO in order to stabilize the differential pressure facing variable influent circumstances. During over one-year of full-scale operation, the treated CIPWW was innovatively supplied for chemical fiber factories which established rigorous limitations on the impurity content of reuse water, and the water quality of purified RO concentrates partially met the requirements of class IV of Environmental Quality Standard for Surface Water (GB3838–2002, China). The application of CaSO 4 crystallizer approximately saved the operation cost by 57.04 % compared with that of Na 2 CO 3 softening process, and sufficiently recycled calcium ions from RO concentrates as CaSO 4 ·2H 2 O products. • Design of a comprehensive reclaimation system for integrated CIPWW with high levels of hardness and salinity. • Improvement of treatment technologies for concentrates generated by RO. • Achievement of low-cost hardness removal and inorganic contaminant resourcilization based on the induced crystallizer with flocculation. • Evaluation of the performance of a full-scale demonstration on integrated CIPWW as well as its RO concentrates. • Detailed analysis on the transformation of refractory organic contaminants, acute toxicity, and fouling status of membranes. [ABSTRACT FROM AUTHOR]

Membrane distillation (MD) and membrane crystallization (MCr) have been applied for treatment of real industrial wastewater to produce high quality sodium sulfate. Simultaneously, MD and MCr minimize waste disposal and generate a fresh water stream. Untreated and wastewater pre-concentrated by nanofiltration have been utilized in MD and MCr under several operative conditions. The untreated wastewater indicated the steadiest performance. The MD and MCr operations have proven their long term stability throughout the concentration of wastewater. The treatment has been continued for more than 90 h for the untreated wastewater. Despite the utilized wastewaters have a high scaling potential in particular for silica, calcium and magnesium, no reduction in flux or wetting of the membrane surface have been observed due to fouling. Moreover, the crystalline product of Na 2 SO 4 recovered as Thenardite (the anhydrous form) exhibits narrow size distribution and low incorporation of impurities. [ABSTRACT FROM AUTHOR]

The ubiquitous use and continuously growing demand for lithium (Li) in transportation and high-technology products have rendered Li+ recovery imperative for sustainable growth. Recently, particular emphasis has been placed on two-dimensional (2D) materials-based membranes due to their superior characteristics compared to ceramic or polymer membranes. This review focuses on the state-of-the-art progress in exploiting applications of newly-developed 2D nanomaterials in selective lithium recovery via membrane-based technology and design of filtration membranes, including selectivity improvement and adding new favorable functionalities like antibacterial, antifouling, and hydrophobicity. From the viewpoint of application, advances in selectivity enhancement via 2D materials, role of these materials as fillers, their benefits, separation, and the transport mechanism of each group are critically assessed, and their drawbacks and prospects of each classification are discussed in detail. In addition to the compendium of basics and reasons behind each ion separation route, experimental outcomes reported in the literature have been comprehensively summarized. Finally, future opportunities for lithium are highlighted to inspire subsequent research. [Display omitted] • Incorporating 2D materials, metal oxide framework (MOFs), transition metal dichalcogenides (TMDs), hexagonal boron nitride (h-BN), different types of MXene, and nanocatalysts as fillers within the texture of ion-selective membranes promises distinctive breakthroughs. • Delving into underlying mechanism of membrane-based processes and analysis of each different approach discussed in the present review article, ushers the path toward selective lithium recovery. • Investigation of the most technical challenges of the membrane crystallization heralds the upcoming next-generation of ion-selective filtration techniques. [ABSTRACT FROM AUTHOR]

In this work, a simple and cost-effective pretreatment upstream an UF membrane operation for the purification of the main olive mill effluent streams (OME) is examined. The raw wastewater was processed by a pH-temperature (T) flocculation process formerly studied at lab scale in previous work. In the present paper, modelization and optimization of the pretreatment process are addressed at pilot scale. Statistical multifactorial analysis showed both pH and T remarkably influence the suspended solids concentration removal efficiency (p-value practically equal to zero), confirming a statistically significant relationship between the variables considered at 95% confidence level. Moreover, the pH exhibits a deeper influence than the T, according to the p-values withdrawn from the analysis, and the squared effects are significant too, but more significant in the case of the pH. Contour plots and response surface support the previous results, and the optimized parameters were 21.4 °C and pH equal to 2.2, yielding 98.4 − 98.6% TSS reduction and 90.5% v / v recovery of clarified water. Finally, a boundary flux value of 9.7 L/hm 2 and a significant reduction of the fouling index (3.4·10 − 2 min − 1 ) were ensured, and a permeate stream reusable for irrigation, boosting the cost-efficiency of the integral process. [ABSTRACT FROM AUTHOR]

Poly-silicic-cation coagulants (PSiCs) with different pH were prepared by synchronous-polymerization. The characteristics and coagulation performances of the coagulants were analyzed. The results show that the crystal, structure and morphology of PSiC are influenced by pH and the optimal preparation pH is 1.5. The crystal analysis shows that some new complex compounds are formed in PSiC. The polymerization form and complexation degree of PSiC with pH of 1.5 are better than at other pH values. The structure and morphology analyses imply that the contents of ionic polymerized bonds, high polymers and irregular PSiC units decrease, and cross-copolymerization of Fe (III) and Al (III) hydroxyl polymers is weakened when pH is too low or too high. Coagulation experiments also indicate that the PSiC with pH value of 1.5 exhibits better coagulation performance in removing turbidity, COD and chroma of paper mill wastewater. [ABSTRACT FROM AUTHOR]

Water treatment is a key aspect for the sustainable management of oil & gas operations. Osmotic concentration (OC) is an advanced water treatment process, adapted from forward osmosis (FO), that does not require water recovery from the draw solution. In this study, two commercial hollow fiber FO membranes [Module 1, cellulose triacetate (CTA) and Module 2, thin film composite (TFC)] were evaluated at pilot scale using actual process water obtained from a gas production facility. The evaluation focused on assessing the membrane productivity, fouling potential and chemical cleaning efficiency while normalizing the performance using a theoretical model that account for the variability of the operating conditions. Performance tests showed that Module 2 has a higher flux compared to Module 1, 9.9 L/m2·h vs 1.7 L/m2·h; and lower specific reverse solute flux (RSF) for most of the ions. Additionally, Module 1 benchmark experiment showed a 13% flux loss attributed to inorganic fouling (calcium phosphate precipitation) while the flux loss in Module 2 was <5% possibly due to enhanced module hydrodynamics and variation in membrane chemistry. Chemical cleaning (citric acid) proved to be successful in restoring the flux for Module 1. From the 8.1 mg/L organic carbon present in the feed, advanced organic characterization revealed that certain group of hydrophilic organics are able to pass through Module 1, but not Module 2, translating to a specific forward organic solute flux of 0.9 mg/L and 0.1 mg/L for Module 1 and 2, respectively. Finally, key sustainable and environmental considerations were presented in support of further development of process implementation. The OC process has strong potential for full-scale installation; however, demonstrating its performance in the field would be the next step necessary for successful implementation of the technology. [Display omitted] • Side-by-side pilot study of 2 commercial FO membranes with industrial wastewater • TFC showed higher water flux (9.9 vs 1.7 L/m2·h) compared to cellulose triacetate. • CTA showed 13% fouling due to calcium phosphate scaling; TFC showed <5% fouling • Certain hydrophilic organics can pass through CTA but not TFC module. • Citric acid cleaning restored the CTA module flux back to their initial performance. [ABSTRACT FROM AUTHOR]

In recent years, it has become very important to reuse wastewater as an alternative water source in industrial zones. Reverse osmosis (RO) membranes are the most used membrane technology for wastewater reuse due to their remarkable divalent and monovalent ions removal efficiencies. However, membrane fouling is a serious problem in RO plants which hinders the membrane performance and shortens the membrane lifespan. In this study, a detailed membrane autopsy study was carried out in fouled RO membrane to characterize the type of membrane fouling obtained from a full-scale industrial zone wastewater reuse plant in Turkey. The autopsy analysis results of the fouled membrane showed that the membrane surface was covered dominantly by inorganic scaling of CaCO 3. Also, there was a remarkable amount of molybdenum (Mo) element on the membrane surface which was attributed to wastewater discharges of automotive industries. Lastly, an appropriate chemical cleaning protocol was proposed. More effective membrane cleaning efficiency was achieved for more acidic agents which was attributed to the presence of inorganic fouling. This study helps to understand the possible fouling formations on the membrane surface used in industrial zone wastewater reuse plants and gives an idea to take necessary precautions for fouling control strategies. • Membrane autopsy in a full-scale industrial zone wastewater reuse plant was carried out. • Inorganic foulants consisted domainantly of calcium carbonate • A remarkable amount of molybdenum (Mo) element was determined on the membrane surface • An appropriate chemical cleaning protocol was proposed. [ABSTRACT FROM AUTHOR]

Nowadays, the recovery processes of precious metals (PMs) from industrial wastewater streams have found significant attractions among various investigators worldwide. PMs are known as rare/noble chemical elements that their fundamental characteristics such as ductility, electrical conductivity, and resistance against corrosion have made them promising for application in industrial-based activities such as jewelry, petrochemistry, and catalysis. The main objective of this review paper is to provide an opportunity for expert as well as non-expert readers to be familiar with the state-of-the-art breakthroughs in the recovery of PMs (i.e., gold (Au), silver (Ag), platinum (Pt), palladium (Pd), ruthenium (Ru), rhodium (Rh), iridium (Ir), osmium (Os), Rhenium (Re) and so on.) from wastewater streams. Apart from the explanation of industrial applications, the recovery process of PMs using various approaches is aimed to be interpreted comprehensively. Eventually, the advantages and disadvantages of applied techniques for the recovery of PMs are discussed, and different approaches as well as future perspectives towards their sustainable use are introduced. [Display omitted] • Critical review on breakthroughs in the recovery of various PMs from wastewater • Discussion about different approaches for PM recovery • Evaluation of the advantages and disadvantages of PM recovery techniques • Future perspectives towards the sustainable use of PMs [ABSTRACT FROM AUTHOR]

Abstract: Over the last 50years, ion exchange membranes have evolved from a laboratory tool to industrial products with significant technical and commercial impacts. Bipolar membranes (BPMs), as a result of their ability to produce acid and alkali from corresponding salt, occupy a special place among them. These properties make it possible to design a number of unique electromembrane processes which have huge industrial impact. These processes include acid and base syntheses, electrochemical regeneration of acidic and basic gas sorbents and ion-exchange resins, protein separation and pH correction of natural waters and juices. The main characteristics that define the possibility of effective BPM application are total potential drop across the membrane and water dissociation current efficiency. These two parameters are closely related to each other and determined by the physical and chemical structures of monopolar layers and the nature of the water dissociation reaction catalyst located in the bipolar region. In this particular article the electrochemical properties of heterogeneous bipolar membranes, methods for investigating them and various theories developed to describe water dissociation are discussed. Comparison between Russian industrial heterogeneous bipolar membranes and various commercial and experimental foreign bipolar membranes is made. In addition, some novel electromembrane processes developed for application of heterogeneous bipolar membranes and their main characteristics are presented. [Copyright &y& Elsevier]

Abstract: The scope of this study is concentration of ammonium from municipal wastewater using ion exchange process. Four types of ion exchange materials were tested in packed bed columns, namely strong and weak acid cation exchange resins and natural and synthetic zeolites. In total 23 runs of saturation and regeneration were done using synthetic wastewaters of different kinds and pretreated municipal wastewater. Due to its high exchange capacity and fast regeneration strong acid cation exchange resin was found to be the most suitable for ammonium concentration under condition that selectivity of ammonium removal is not of a main concern and it allows concentrating ammonium from 27 to 580mg NH4-N/L. If selective ammonium removal is required, natural zeolite should be used instead. Regeneration with 0.17M HCl and 0.17–0.51M NaCl was tested and suitability of different regenerants for different technologies of spent regenerant treatment was discussed. It was shown that electric conductivity measurements can be used for detection of breakthrough and estimation of ammonium concentration in outflow from an ion exchange column. Breakthrough curve fitting with Thomas and Adams–Bohart models was performed which gave information about the maximum exchange capacity of materials and kinetics of ion exchange. [Copyright &y& Elsevier]

This study describes an emerging technology for near-zero liquid discharge desalination (ZDD) and salt reclamation using electrodialysis metathesis (EDM) to treat high-salinity wastewater with high scaling potential. Response surface methodology was employed to determine the optimal conditions for EDM-based ZDD process, and Box-Behnken center-united experimental design was used to quantify the effects of superficial velocity, applied voltage, and volume ratio of diluate/concentrate streams (V c / V d) on the salt removal ratio and current efficiency. These parameters influenced the outcome with the impacts following: voltage > superficial velocity > V c / V d , and the interactions were generally weak. The concentration of Na- and Cl-type liquid salts reached 200 and 170 g/L, respectively, after seven batch operations without scaling risks. Moreover, the two concentrate streams could be combined to precipitate CaSO 4 with about 60% removal of Ca2+ via production of a solid byproduct. Alkali-assisted precipitation of the residual stream demonstrated efficient recovery of Mg2+ resources. Additionally, the purified solution could be further utilized to recover chemical resources (NaCl and Na 2 SO 4) through a partial crystallization process. This work thus provides an applicable approach for the ZDD and reclamation of high-salinity wastewater with high scaling potential, which exist widely in seawater desalination engineering and industrial wastewater treatment. [Display omitted] • An emerging zero-discharge desalination process without scaling potential was proposed. • EDM could be technically feasible to convert and concentrate wastewater with scaling potential. • Effects of typical EDM parameters on the wastewater conversion were systematic studied. • The two concentrate streams could be combined to precipitate CaSO 4 with about 60% removal of Ca2+. [ABSTRACT FROM AUTHOR]

The harmful effects arisen from the discharge of saline wastewater have become more evident in recent years and therefore drawn much public concerns. Saline wastewater, including produced water, tannery wastewater, textile wastewater and aquaculture wastewater, contains various organic pollutants and inorganic dissolved ions. These saline wastewaters can be treated, not only to meet the discharge standard but also to offer the opportunities for water reuse and nutrient recovery. Membrane technology is a promising technology that offers attractive solutions for effective saline wastewater treatment and resource recovery. With the tremendous development made in this realm, this review is set to provide a frame of state-of-the-art approaches for saline wastewater treatment based on membrane technology and stimulate ideas to enhance the treatment efficiency and sustainability in these related works. The unique features, strengths and limitations of pressure-driven, osmotically-driven, thermally-driven and electrically-driven membrane processes in treating saline wastewater and resource recovery are discussed. This review aims to consolidate the literature related to membrane technology as a versatile tool for saline wastewater treatment, as well as to identify the current research gaps and areas of improvement related to this field. • Various membrane-based separation processes for saline wastewater treatment and resource recovery are discussed. • Pressure-driven membrane processes are reliable and effective for saline wastewater treatment and recovery. • Forward osmosis, membrane distillation and electrodialysis are feasible alternatives. • Integrations among membrane processes or with conventional treatment processes provide more holistic solutions. • The current research gaps and the future directions are highlighted. [ABSTRACT FROM AUTHOR]

Abstract: A simple and low-cost method was developed to prepare poly-silicic-cation coagulant (PSiC) from industrial wastes. The structure and morphology of the coagulants with different Si/(Al+Fe) molar ratios were characterized by X-ray diffraction (XRD), infrared spectra (IR), ultraviolet/visible absorption (UVA) scanning and microscopic imaging, and the coagulation performances were evaluated by papermaking wastewater treatment. The results show that instead of a simple mixture of the raw materials, new complex compounds are formed in all the PSiCs, and distinctive compounds are found in each PSiC. Furthermore, with the increasing dose of silicon in PSiC, the contents of the ionic polymerized bonds and the high polymers are decreased obviously, and the cross-copolymerization of Fe (III) and Al (III) hydroxyl polymers is weakened. Morphological analysis implies that branch-like PSiC units become smaller with the increase of Si/(Al+Fe) molar ratio, and coagulation experiments indicate that the PSiC with lower Si/(Al+Fe) molar ratio exhibits better coagulation performance in removing turbidity, COD and chroma. [Copyright &y& Elsevier]

Abstract: The removal of salts from industrial effluents by sustainable techniques is of great interest to many companies. In this study, an industrial saline water, mainly composed of NaCl and KCl, was treated with conventional electrodialysis (ED) and bipolar membrane electrodialysis (EDBM) on lab-scale. The saline water also contained significant amounts of sulfate and calcium, which may give rise to various types of scaling. A partial desalination (target was a removal of 50% of the chlorides) was easily achieved with both ED and EDBM. By using ED, a concentrate containing circa 2M of chlorides was obtained. The formation of scaling was avoided by using monovalent selective anion- and cation-exchange membranes, which was particularly necessary to avoid CaSO4 scaling. A further improvement was obtained by applying EDBM, which yielded an acid and a base stream with a concentration of around 2M, with a relatively good purity. From the initial lab-scale study it was concluded that both ED and EDBM are technologically feasible to desalinate the saline water. In a second phase, the ED scenario was scaled up in a pilot scale study, which demonstrated that the ED pilot plant was operated in a stable way during a long-term experiment. [Copyright &y& Elsevier]

Abstract: Recently, for some membrane separation processes, the concept of threshold flux was introduced in substitution of the critical one. The new concept applies to all systems which trigger fouling formation from start of operation, even at very low operating conditions, and in particular to the purification of olive mill wastewater streams by membranes. The operation of a spiral-wound nanofiltration membrane module used to purify different pretreated olive mill wastewater streams and how pretreatments affect the threshold flux values and the threshold flux fitting parameters will be discussed. [Copyright &y& Elsevier]

Abstract: A 5nm TiO2 ceramic ultrafiltration membrane was evaluated with respect to beverage production wastewater. The influence of operating parameters such as crossflow velocity (CFV), transmembrane pressure (TMP) and particle size distribution on filtration performance was investigated. Results show that certain combinations of higher CFVs and TMPs provide significant improvements in permeate flux and contaminant rejection rates. These improvements are attributed to the turbulent flow regime experienced by suspended particles during ultrafiltration. At higher CFVs of 3.1 and 3.6ms−1, the majority of the particles present in the wastewater are swept away from the membrane surface resulting in reduced concentration polarization (cake layer) resistance and improved permeate flux. The steady-state permeate fluxes measured at CFVs of 3.1 and 3.6ms−1 increased by 22% and 53% respectively when TMP was increased to 200kPa. Increasing the TMP further to 300kPa also increased the steady-state permeate fluxes by 16% and 4% respectively. Similarly, the reduction in concentration polarization resistances at these CFVs also reduced particle infiltration into the membrane pores resulting in better filtrate quality in terms of turbidity and COD. A CFV of 3.1ms−1 and a TMP of 300kPa were identified as optimal operating conditions in terms of energy consumption and permeate flow rate. [Copyright &y& Elsevier]

Abstract: The subject of the research was treatment of industrial waste water generated in the production process during the washing of reactors (and partly also of the floor) after the production of powder and liquid detergents. This study demonstrated the removal efficiency of adsorbable organic halogens (AOX) during micellar-enhanced ultrafiltration (MEUF) in the presence of anionic and nonionic surfactants simulated in model samples and verified by testing real samples. Mechanism is based on the fact, that the surfactant monomers assemble into micelles which are large enough to be retained by the UF membrane. The hollow fibre membrane module made of polyvinylidenedifluoride (PVDF) was used. We have found that the retention of AOX on the membrane is strongly dependent on several factors: the nature and characteristic of surfactants and especially on the presence of electrolytes in waste water and that retention exceeds 80% in cases when conductivity of waste water is at least 4.0mS/cm. The decreases in the concentration of both anionic and non-ionic surfactants exceeded 90%. [Copyright &y& Elsevier]

Abstract: Using the extraction replacement–biodegradation coupling technique, the removal of chemical oxygen demand (CODcr) from coking wastewater was successfully carried out, and the appropriate extractant type, extractant/diluter ratio, extraction time, and the extractant/wastewater phase ratio were also determined. The results show that when n-octanol and cyclohexane, in a ratio of 1:1, were selected as the mixed extractant, nitrogen-containing heterocyclic compounds (NHCs), such as pyridines and quinolines, were effectively extracted and replaced by the extractant from coking wastewater. As a result, the biodegradable nature of coking wastewater could be improved significantly. After pretreating coking wastewater with the extraction replacement method for 5min using a 1:1 ratio of extractant to wastewater and following with biodegradation treatment, the biochemical oxygen demand for five days (BOD5)/CODcr values and the CODcr removal efficiencies of the coking wastewater effluent were improved from 0.06 to 0.29 and from 68.81% to 88.63%, respectively. The result of economic feasibility analysis shows that, by controlling the treaded quantity and concentration of coking wastewater, the extraction replacement–biodegradation coupling process can become a profitable project. [Copyright &y& Elsevier]

Abstract: Treatability of paint manufacturing wastewater (PMW) by electrocoagulation (EC) process was investigated. Effects of operating parameters for the EC process such as electrode type (Al or Fe), initial pH (2–10), current density (5–80A/m2) and operating time (0–50min) were evaluated for optimum operating conditions. The highest removal efficiencies for COD and TOC in PMW were obtained with 93% and 88% for Fe and 94% and 89% for Al electrodes at the optimum conditions (35A/m2, 15min and pH 6.95). Operating costs for removal of PMW at the optimum conditions were calculated for Fe and Al electrodes as 0.187€/m3 and 0.129€/m3. Toxicity test was carried out to obtain information about toxic effect of the raw and treated wastewaters at optimum operating conditions. The samples measured by respirometric method contained hardly toxicities. Performance of Al electrode was better than that of Fe electrode in terms of removal efficiency and operating cost. [Copyright &y& Elsevier]

Abstract: Fenton process was employed to pretreat the acrylic fiber manufacturing wastewater. The operation conditions were as follows: H2O2 and ferrous dosages were 100–800mg/L; pH value was 1–7; reaction time was 0.5–4.0h. In terms of COD removal and biodegradability improvement, the optimal conditions were as follows: ferrous content was 300mg/L; hydrogen peroxide was 500mg/L; pH value was 3.0; reaction time was 2h. With these conditions, the overall COD removal and effluent B/C could arrive at 65.5% and 0.529 respectively. The biodegradability of the acrylic fiber manufacturing wastewater was increased by 429%. It was unnecessary to achieve complete mineralization of the organic compounds into carbon dioxide and water. Partial oxidation of intermediate compounds could minimize the consumption of chemical reagents and result in substantial reduction of COD and toxicity. The further biological treatment was favored by acquiring degradable low molecular weight components. [Copyright &y& Elsevier]

Abstract: Effluent organic matter (EfOM) in secondary wastewater effluent (SWWE) contains a wide range of organic compounds, which varies depending on wastewater treatment plant performance. Its removal is required for various reuse/recycling applications. Traditionally, enhanced coagulation (EC) process is followed by biological activated carbon (BAC), EC/BAC combination, in order to obtain additional dissolved organic carbon (DOC) removal. However, this study elucidates the effectiveness of BAC/EC combination by modelling DOC removal resulting from EC of SWWE and BAC effluent obtained at different empty bed contact time (EBCT). The result suggests that BAC reduces the coagulant non-sorbable DOC concentration significantly which otherwise remains unaffected by the traditional combination. Further, non-sorbable concentration decreased with increased EBCT. This clearly indicates the crucial role of biological activities on increasing the performance of coagulant. [Copyright &y& Elsevier]

Abstract: This work deals with investigation of electrochemical technique for the treatment of milk liquid fractions. The removal of COD, phosphate and turbidity was investigated by varying the operating conditions. The batch experimental results revealed that the removal efficiencies of the overall turbidity, COD and phosphate concentration, depend on the nature of the electrodes material. The results indicated that turbidity is eliminated only by coagulation process and depends principally on aluminum concentration, whereas, soluble COD and phosphate might be eliminated by indirect oxidation. The greatest removal efficiency was obtained with the use of both cathode and anode made of aluminum (Al–Al system). With this latest system, optimal values of current density, initial pH, NaCl concentration and electrolysis time were 0.5mA/cm2, 6.6, 1.5g/L and 2min respectively. For these optimal parameter values, the removal efficiency of COD, phosphate and turbidity attained respectively 80%, 59% and 96%. Corresponding energy consumption was very low and equal 0.03kWh/kg and 0.04kWh/kg, for COD and phosphate removal respectively. Scanning electron microscopy (SEM), energy dispersion spectra (EDS) and fourier transform infrared spectroscopy (FT-IR), were used to characterize the resulting sludge. [Copyright &y& Elsevier]

Abstract: The positive effect of bacterial cell immobilisation on the performance of biological nitrogen removal was demonstrated in three different cases. Selectively cultivated nitrification or denitrification bacteria were immobilised using proprietary Lentikats Biotechnology in a porous hydrogel matrix made of polyvinyl alcohol. The biocatalysts were used for nitrogen removal from various types of industrial wastewater, i.e. wastewater with high salinity (brines) or high concentrations of toxic compounds (diphenylguanidine manufacturing, uranium mining residues). The cell immobilisation resulted in an increased robustness of the nitrification and denitrification cultures towards unfavourable operational conditions. [Copyright &y& Elsevier]

Abstract: Heavy metal ion contamination in drinking water poses a major risk to human health, whilst contamination in wastewater streams can cause damage to the wider environment. In this study carbon nanocages, synthesised using a supercritical fluid deposition method, were examined as adsorbents of Pb2+ ions from aqueous solutions. Through careful selection of the catalyst and the carbon deposition temperature and pressure, high yields of nanocages with surface areas up to 1175m2 g−1 were synthesised. These high surface area materials were subsequently tested for their ability to absorb Pb2+ ions, as a function of pH, from simulated wastewater. The nanocages were found to be effective at removing the Pb2+ ions at levels of 11.1mgg−1, compared to 7.6mgg−1 for commercially available activated carbon. The kinetics of metal ion adsorption by the nanocages and activated carbon can be described by a pseudo-second-order kinetics model, with a rate coefficient (k 2) of 4.8×102 gmg−1 min−1. [Copyright &y& Elsevier]

Abstract: Disinfection studies with two pure strains of Escherichia coli ATCC 11229 and ATCC 15597 and real municipal wastewater were carried out at laboratory scale with a 10W low pressure ultraviolet lamp in an ultraviolet (UV) disinfection system with recirculation of the liquid. A double first order kinetic model was established to fit the ultraviolet disinfection curves for the two microorganisms. This model implies that there are two subpopulations within the study population, one of which is sensitive to ultraviolet and another that is radiation-resistant. The kinetic model depends on the applied UV dose and is directly related to the initial bacterial concentration (No). It was possible to establish relationships between the kinetic parameters of the equation and the initial concentration, and so to predict the disinfection curves. The kinetic model was successfully fitted to a real wastewater sample, with the final microbial disinfection predicted as a function of the UV dose and No. [Copyright &y& Elsevier]