Enhancement of fouling resistance of microfiltration membranes by surface modification using UV-curing photopolymer.

Membrane fouling, a major problem in membrane-based processes, decreases the water permeability of a membrane. Membrane fouling can be mitigated either by the application of an additional process for membrane cleaning and pretreatment or by fabricating and modifying membranes to achieve low surface interaction forces. This study aimed to improve the fouling resistance of a commercially available membrane by modifying it with a UV-cured photopolymer, MINs, to achieve low surface energy. The morphological variations (thickness and pore size distribution) of the coating layer were most affected by the viscosity of the UV-cured photopolymer. The thickness of the coating layer was inversely proportional to the dilution factor of the MINs. The pore size distribution could be adjusted by surface modification, and the smallest pore size range (0.077-0.078 µm) was observed for the MC5 membrane. In addition, the pore size distribution, surface roughness, and zeta potential of the membrane decreased after the surface modification. Thus, the developed surface modification strategy has potential for improving the fouling resistance of commercially available microfiltration membranes.

Enhancement of denitrification by sulfur-based carrier in sequencing batch reactor (SBR) for advanced wastewater treatment.

This study was to enhance the nitrogen removal efficiency in the sequencing batch reactor (SBR) process by adding sulfur-based carriers. The nitrogen removal efficiency of the control group was compared with that of the experimental group through a two-series operation of SBR1 without carrier and SBR2 with the carrier under the condition of no external carbon source. A total nitrogen (T-N) removal efficiency of 6.6%, 72.6%, and 79.9% was observed in SBR1, SBR2 (5%), and (10%), respectively. The T-N removal efficiency was improved in the system with carriers, which showed an increase in the removal efficiency of approximately 91.7%. The results suggest that the inclusion of the carrier led to an elevation in the sulfur ratio, implying an augmented surface area for sulfur-based denitrifying microorganisms. Additionally, CaCO3 contributed essential alkalinity for sulfur denitrification, thereby preventing a decline in pH. Regardless of the carrier, the efficiency of organic matter removal surpassed 89%, indicating that the sulfur-based carrier did not adversely affect the biological reaction associated with organic matter. Therefore, autotrophic denitrification was successfully performed using a sulfur carrier in the SBR process without an external carbon source, improving the nitrogen removal efficiency.

A novel approach to measure carbonate alkalinity in aqueous solutions using a total organic carbon analyzer.

Carbonate alkalinity is crucial in regulating the pH and buffering capacity of natural water systems. Thus, its accurate measurement is essential to understand various water environments that affect water quality and ecosystem health. However, conventional potentiometric titration has some limitations. It results in inaccurate measurements of carbonate alkalinity when the alkalinity levels are low or when high dissolved organic matter or inorganic ion levels exist. Herein, we propose a novel approach to accurately measure carbonate alkalinity using a total organic carbon (TOC) analyzer. An extensive study comparing the accuracy and reliability of the conventional potentiometric titration method with those of the newly developed TOC method was conducted to develop and verify highly accurate measurements of carbonate alkalinity. The TOC method has several advantages over the conventional potentiometric titration methods, such as its ability to accurately measure carbonate alkalinity in the presence of high dissolved organic matter or inorganic ion levels and its ability to provide rapid and automated measurements with high reproducibility. Because, the limit of detection, limit of quantification, and the variation coefficient of the measurements was 0.016 mM (0.2 mgC/L), 0.050 mM (0.6 mgC/L), and 3.68 % respectively. Thus, the development of a novel TOC method has significant environmental implications as it provides a reliable and accurate means to measure carbonate alkalinity in solutions containing various organic matter types.

Exposure dose and temperature of chlorine on deterioration of thin-film composite membranes for reverse osmosis and nanofiltration.

In this study, the effect of chlorine, which is used as a chemical cleaning agent or disinfection agent on membrane deterioration, was analyzed under various conditions during the membrane process. Reverse osmosis (RO: ESPA2-LD and RE4040-BE) and nanofiltration (NF: NE4040-70) membranes made of polyamide (PA) thin film composite (TFC) were used for evaluation. Chlorine exposure was performed at doses ranging from 1000 ppm h to 10,000 ppm h using 10 ppm and 100 ppm, and temperatures from 10 °C to 30 °C. Raw water containing NaCl, MgSO4, and dextrose was used to compare the filtration performance after exposure to each of the conditions studied. Reduction in removal performance and enhancement in permeability were observed as chlorine exposure increased. Attenuated total reflectance-Fourier transform infrared (ATR-FTIR) spectroscopy and scanning electron microscope (SEM) were employed to determine the surface characteristics of the decomposed membranes. ATR-FTIR was used to compare the intensity of the peaks related to the TFC membrane. Based on the analysis, the state of membrane degradation was elucidated. SEM was used to confirm visual degradation of the membrane surface. Permeability and correlation analyses were performed on CnT as an index for determining membrane lifetime in order to investigate the power coefficient. The relative influence of the exposure concentration and time on membrane degradation was explored by comparing the power efficiency according to the exposure dose and temperature.

Status and future trends of hollow fiber biogas separation membrane fabrication and modification techniques.

With the increasing global demand for energy, renewable and sustainable biogas has attracted considerable attention. However, the presence of various gases such as methane, carbon dioxide (CO2), nitrogen, and hydrogen sulfide in biogas, and the potential emission of acid gases, which may adversely influence the environment, limits the efficient application of biogas in many fields. Consequently, researchers have focused on the upgrade and purification of biogas to eliminate impurities and obtain high-quality and high-purity biomethane with an increased combustion efficiency. In this context, the removal of CO2 gas, which is the most abundant contaminant in biogas, is of significance. Compared to conventional biogas purification processes such as water scrubbing, chemical absorption, pressure swing adsorption, and cryogenic separation, advanced membrane separation technologies are simpler to implement, easier to scale, and incur lower costs. Notably, hollow fiber membranes enhance the gas separation efficiency and decrease costs because their large specific surface area provides a greater range of gas transport. Several reviews have described biogas upgrading technologies and gas separation membranes composed of different materials. In this review, five commonly used commercial biogas upgrading technologies, as well as biological microalgae-based techniques are compared, the advantages and limitations of polymeric and mixed matrix hollow fiber membranes are highlighted, and methods to fabricate and modify hollow fiber membranes are described. This will provide more ideas and methods for future low-cost, large-scale industrial biogas upgrading using membrane technology.

Removal of nitrogen from municipal wastewater by denitrification using a sulfur-based carrier: A pilot-scale study.

In the present study, to improve nitrate removal rate, a sulfur-based carrier was applied for autotrophic denitrification, and the removal rate was evaluated for advanced wastewater treatment without adding any external organic carbon source. Based on the results, an increased PAC concentration affected the removal efficiency of NO3--N, and the optimal concentration of PAC was at 15 wt%. During the 60 d operation of a pilot process with a capacity of 1 m3/d, the removal of T-N was 81.2% and 50.2% in reactors with and without sulfur-based carrier, respectively. The removal efficiency of NO3--N exhibited a similar trend to that of T-N. According to the results, the removal of T-N and NO3--N was noticeably enhanced to approximately 30% by adding a sulfur-based carrier to the A2O pilot system. In addition, microbial community in both reactors was dominated by Thiobacillus, which is an autotrophic microorganism, displaying a dominant denitrification status. The present study compared the relative efficiencies of nitrate removal in A2O pilot reactors with and without sulfur-based carriers for its successful application in real-scale autotrophic denitrification.

Fabrication Techniques for Graphene Oxide-Based Molecular Separation Membranes: Towards Industrial Application.

Graphene oxide (GO) has been a prized material for fabricating separation membranes due to its immense potential and unique chemistry. Despite the academic focus on GO, the adoption of GO membranes in industry remains elusive. One of the challenges at hand for commercializing GO membranes lies with large-scale production techniques. Fortunately, emerging studies have acknowledged this issue, where many have aimed to deliver insights into scalable approaches showing potential to be employed in the commercial domain. The current review highlights eight physical methods for GO membrane fabrication. Based on batch-unit or continuous fabrication, we have further classified the techniques into five small-scale (vacuum filtration, pressure-assisted filtration, spin coating, dip coating, drop-casting) and three large-scale (spray coating, bar/doctor blade coating, slot die coating) approaches. The continuous nature of the large-scale approach implies that the GO membranes prepared by this method are less restricted by the equipment's dimensions but rather the availability of the material, whereas membranes yielded by small-scale methods are predominately limited by the size of the fabrication device. The current review aims to serve as an initial reference to provide a technical overview of preparing GO membranes. We further aim to shift the focus of the audience towards scalable processes and their prospect, which will facilitate the commercialization of GO membranes.

Energy recovery through reverse electrodialysis: Harnessing the salinity gradient from the flushing of human urine.

Urine dilution is often performed to avoid clogging or scaling of pipes, which occurs due to urine's Ca2+ and Mg2+ precipitating at the alkaline conditions created by ureolysis. The large salinity gradient between urine and flushing water is, theoretically, a source of potential energy which is currently unexploited. As such, this work explored the use of a compact reverse electrodialysis (RED) system to convert the chemical potential energy of urine dilution into electric energy. Urine' composition and ureolysis state as well as solution pumping costs were all taken into account. Despite having almost double its electric conductivity, real hydrolysed urine obtained net energy recoveries ENet of 0.053-0.039 kWh/m3, which is similar to energy recovered from real fresh urine. The reduced performances of hydrolysed urine were linked to its higher organic fouling potential and possible volatilisation of NH3 due to its high pH. However, the higher-than-expected performance achieved by fresh urine is possibly due to the fast diffusion of uncharged urea to the freshwater side. Real urine was also tested as a novel electrolyte solution and its performance compared with a conventional K4Fe(CN)6/K3Fe(CN)6 couple. While K4Fe(CN)6/K3Fe(CN)6 outperformed urine in terms of power densities and energy recoveries, net chemical reactions seemed to have occurred in urine when used as an electrolyte solution, leading to TOC, ammonia and urea removal of up to 13%, 6% and 4.4%, respectively. Finally, due to the migration of K+, NH4+ and PO43-, the low concentration solution could be utilised for fertigation. Overall, this process has the potential of providing off-grid urine treatment or energy production at a household or building level.

Reverse osmosis membrane fabrication and modification technologies and future trends: A review.

Reverse osmosis (RO) is the most widely used technology in water treatment and desalination technologies for potable water production. Since its invention, RO has undergone significant developments in terms of material science, process, system optimization, methods of membrane synthesis, and modifications. Among various materials used for the synthesis of an RO membrane, the polyamide thin-film composite (PA-TFC) is by far the most common, owing to its excellent water permeability high salt rejection, and stability. However, a tradeoff between membrane permeability and salt rejection and membrane fouling has been a major hindrance for the effective application of this membrane. Thus, a broad investigation has been carried out to address these problems, and among which co-solvent interfacial polymerization (CAIP) and the surface modification of substrates and active layers of RO membrane have been the most effective approaches for controlling and improving the surface properties of the PA-TFC membrane. In this review paper, the problems associated with the RO membrane processes and strategies has been discussed and addressed in detail. Furthermore, as the focus of this review, the major advancements in the strategies used for enhancement of RO membrane performance through CAIP, and surface modifications were scrutinized and summarized.

A pilot study of spiral-wound air gap membrane distillation process and its energy efficiency analysis.

Brine disposal is a major drawback for seawater desalination. Membrane distillation (MD) is an emerging technology to treat a high saline water including brine disposal instead of reverse osmosis, multi-stage flash and multi-effect distillation. This study investigated a pilot scale of a spiral-wound air gap MD (AGMD) module and evaluated its efficiency. A pilot-scale AGMD module with design production capacity of 10 m3/d was operated. Experiments with varying flow velocity showed increasing trend of water vapor flux as flow velocity increases. The temperature is one of the significant points in maximizing water permeate vapor flux in MD. Increasing temperature from 65 °C to 75 °C in evaporator channel has increased flux from 0.59 to 1.15 L/m2/h. Under various conditions, specific thermal energy consumption (STEC) and gained output ratio (GOR) was used to analyze energy efficiency. The pilot plant showed high GOR value in spite of a limited heating and cooling source available at the site. The highest GOR achieved was 3.54 with STEC of 182.78 kWh/m3. This study provides an overview of operation experience and its data analysis related to temperature, concentration, flow rate and energy supply.

Removal of fluoride in membrane-based water and wastewater treatment technologies: Performance review.

The presence of excess fluoride in aqueous media above local environmental standards (e.g., the U.S. Environmental Protection Agency (EPA) standard of 4 mg/L) affects the health of aquatic life. Excess fluoride in drinking water above the maximum contaminant level (e.g., the World Health Organization (WHO) standard of 1.5 mg/L) also affects the skeletal and nervous systems of humans. Fluoride removal from aqueous solutions is difficult using conventional electrochemical, precipitation, and adsorption methods owing to its ionic size and reactivity. Thus, new technologies have been introduced to reduce the fluoride concentration in industrial wastewater effluents and various drinking water sources. Membrane technology is one of the newer technologies found to be very effective in significantly reducing fluoride to desired standards levels; however, it has received less attention than other technologies because it is perceived as a costly process. This study critically reviewed the performance of various membrane process and compared it with effluent and zero liquid discharge (ZLD) standards. The performance review has been conducted with the consideration of the theoretical background, rejection mechanisms, technical viability, and parameters affecting flux and rejection performance. This review includes membrane systems investigated for the defluoridation process but operated under pressure (i.e., reverse osmosis [RO] and nanofiltration [NF]), temperature gradients (i.e., membrane distillation [MD]), electrical potential gradients (i.e., electrodialysis [ED] and Donnan dialysis [DD]), and concentration differences (i.e., forward osmosis [FO]). Moreover, the study also addressed the advantages, limitations, & applicable conditions of each membrane based defluoridation process.

Membrane-based technologies for zero liquid discharge and fluoride removal from industrial wastewater.

Several defluoridation techniques for reducing high initial fluoride concentration (IFC) in wastewater have been tested, but only a few of them have achieved the permissible standards. This study examined the hybrid crystallization-reverse osmosis technique (HRO) in light of flux, fluoride removal efficiency, fouling tendency, mineral recovery, complying zero liquid discharge (ZLD), and effluent discharge standard (EDS). Simulated wastewater with an IFC of 6600 mg/L was utilized and the final HRO performance was compared with those of the low-pressure (30 bar) standalone reverse osmosis (SRO), nanofiltration (SNF), and membrane distillation (SMD) processes. Accordingly, the study on SRO and SNF revealed that pressure, feed pH, membrane type, and IFC were the major factors affecting performance, and SRO was unable to sufficiently defluoridate wastewater with IFC >614 mg/L, needing pretreatment. Subsequently, the HRO process was selected and it was seen that the optimum calcium dose and respective final effluent pH for attaining EDS and ZLD were 16.5 g/L & 7.1 and 19.8 g/L & 5.7 respectively. The best operating pH for all conditions in HRO was approximately 9. Additionally, HRO showed good mineral recovery tendency and less organic fouling. The overall comparisons of flux and residual fluoride for HRO, SRO, SNF, and SMD were 49.3 LMH & 1.21 mg/L; 34.9 LMH & 62 mg/L, 44.05 LMH & 301 mg/L, and 38 LMH & 0.9 mg/L respectively. Therefore, low-pressure HRO can be applied to treat wastewater with high IFC; good tendency of mineral recovery, as good as that of SMD.

Analysis of mass transfer behavior in membrane distillation: Mathematical modeling under various conditions.

Four commercially available hydrophobic membranes with different pore sizes were separately used in a direct contact membrane distillation (DCMD) apparatus to investigate the effect of fouling on the mass transfer coefficient, and the dominant mass transport mode under different conditions defined by the temperature, membrane material, flow regime, and membrane pore size. Both ultrapure deionized water and simulated industrial wastewater were considered as the feed water. The results of the investigation confirmed that the fouling layer impacted the mass transport directly by resisting it, and indirectly by altering the heat transfer mechanism. In addition to the surface fouling layer, a significant number of particles were also observed to accumulate in the membrane pores. It was further determined that the contribution of Poiseuille flow to the entire mass transport was significant at higher temperatures when using a membrane with large pores. This highlighted the need for careful consideration of Poiseuille flow in the modeling and simulation of a membrane distillation (MD) mass transport process. It was also observed that the flow rate did not affect the Poiseuille flow and therefore did not directly impact the entire mass transfer. The study findings provide systematic insight for the development of a strategy for selecting an appropriate operating feed for DCMD and adjusting the permeate temperature to fit the prevailing water demand and environmental conditions.

Nanoscale zero-valent iron (nZVI) immobilization onto graphene oxide (GO)-incorporated electrospun polyvinylidene fluoride (PVDF) nanofiber membrane for groundwater remediation via gravity-driven membrane filtration.

Nanoscale zero-valent iron (nZVI), with its high reactivity towards a broad range of contaminants, has been a promising material for groundwater remediation. Membrane-supported nZVI can both avoid nZVI agglomeration for better reactivity and recycle nZVI to lower the risk of secondary pollution. In this study, we successfully fabricated a PVDF-GO membrane via electrospinning technology and employed the functionalized nanofiber membrane to immobilize nZVI particles. The addition of GO into PVDF nanofibers can both increase the hydrophilicity to improve membrane flux and offer -COOH as a binder to immobilize nZVI particles. PVDF-GO-nZVI membranes with different GO loadings (0%, 0.5%, 1%, 3% of PVDF) were tested with two typical nZVI-targeted contaminants (Cd(II) and trichloroethylene (TCE)) via gravity-driven membrane filtration. The results show that membrane with 1% GO had the best nZVI distribution against the aggregation and a better performance in both Cd removal (100%) and TCE removal (82%). The nZVI membrane had a high flux in gravity-driven filtration at 255 LMH for Cd(II) and 265 LMH for TCE respectively. Generally, the developed PVDF-GO-nZVI electrospun nanofiber membrane had an excellent performance in the gravity-driven membrane filtration system for groundwater remediation.

Improving membrane distillation performance: Morphology optimization of hollow fiber membranes with selected non-solvent in dope solution.

This study aimed at improving membrane distillation (MD) performance by mixing various non-solvents (NSs) in polymer dope solutions. The effect of each NS on the inner structure and surface morphology of hollow fiber (HF) membrane was investigated. Membrane morphology is manipulated by controlling liquid-liquid (L-L) and solid-liquid (S-L) demixing time, which is a function of the viscosity and water affinity of dope solutions. Consequently, the addition of NSs altered membrane morphology by affecting the diffusion rate during NS induced phase separation (NIPS) process. The performance results showed that the dope solution composed of 11/71.2/17.8 wt% polyvinylidene fluoride (PVDF)/triethyl phosphate (TEP)/toluene produced the most promising HF membrane for MD. The optimal membrane demonstrated a unique bicontinuous structure with increased porosity and mean pore size. The addition of toluene as NS in dope solutions enhanced crystallization process, which increased the Young's modulus of membrane but slightly decreased its maximum tensile strength at break. The optimal PVDF HF membrane demonstrated a steady flux of 18.9 LMH at 60 °C/20 °C of feed/permeate temperatures and a salt rejection of 99.99% when tested for 72 h. The results suggest that incorporation of toluene as a NS into PVDF dope solutions can increase permeation performance in MD by enhancing the morphology of HF membranes.

Volatile fatty acids and biogas recovery using thermophilic anaerobic membrane distillation bioreactor for wastewater reclamation.

The effects of bioreactor temperatures and salinities of an anaerobic membrane distillation bioreactor (anMDBR) on the permeation performance and their potential recovery of bioresources were fully examined in this study. To the best of our knowledge, this is the first study of a lab-scale anMDBR process utilizing sub-merged hollow fiber membranes. The hybrid system utilizing both membrane distillation (MD) and anaerobic bioreactors achieved 99.99% inorganic salt rejection regardless the operation temperatures and high initial flux from (2-4 L m-2 h-1) at 45-65 °C. However, after 7-day operation, the flux dropped by 16-50% proportional to the bioreactor temperatures. It was found that the effects of bioreactor temperatures had strong impacts on both the permeation performance and fouling behavior while salinity had insignificant effect. A compact non-porous fouling layer was observed on the membrane surface from the bioreactor operated at 65 °C while only a few depositions was found on the membrane from 45 °C bioreactor. In the present study, the optimal anMDBR temperature was found to be 45 °C, showing a balanced biogas production and membrane permeation performance including less fouling formation. At this bioreactor temperature (45 °C), the biogas yield was 0.14 L/g CODremoval, while maintaining a methane recovery of 42% in the biogas, similar recovery to those at bioreactor temperatures of 55 and 65 °C. The potential recovery of volatile fatty acids made anMDBR a more economically efficient system, in addition to its lower operation cost and smaller footprint compared with most other technologies for on-site wastewater treatment.

Core-Shell Interface-Oriented Synthesis of Bowl-Structured Hollow Silica Nanospheres Using Self-Assembled ABC Triblock Copolymeric Micelles.

Hollow porous silica nanospheres (HSNs) are emerging classes of cutting-edge nanostructured materials. They have elicited much interest as carriers of active molecule delivery due to their amorphous chemical structure, nontoxic nature, and biocompatibility. Structural development with hierarchical morphology is mostly required to obtain the desired performance. In this context, large through-holes or pore openings on shells are desired so that the postsynthesis loading of active-molecule onto HSNs via a simple immersion method can be facilitated. This study reports the synthesis of HSNs with large through-holes or pore openings on shells, which are subsequently termed bowl-structured hollow porous silica nanospheres (BHSNs). The synthesis of BHSNs was mediated by the core-shell interfaces of the core-shell corona-structured micelles obtained from a commercially available ABC triblock copolymer (polystyrene- b-poly(2-vinylpyridine)- b-poly(ethylene oxide) (PS-P2VP-PEO)). In this synthesis process, polymer@SiO2 composite structure was formed because of the deposition of silica (SiO2) on the micelles' core. The P2VP block played a significant role in the hydrolysis and condensation of the silica precursor, i.e., tetraethylorthosilicate (TEOS) and then maintaining the shell's growth. The PS core of the micelles built the void spaces. Transmission electron microscopy (TEM) images revealed a spherical hollow structure with an average particle size of 41.87 ± 3.28 nm. The average diameter of void spaces was 21.71 ± 1.22 nm, and the shell thickness was 10.17 ± 1.68 nm. According to the TEM image analysis, the average large pore was determined to be 15.95 nm. Scanning electron microscopy (SEM) images further confirmed the presence of large single pores or openings in shells. These were formed as a result of the accumulated ethanol on the PS core acting to prevent the growth of silica.

Membrane distillation for industrial wastewater treatment: Studying the effects of membrane parameters on the wetting performance.

Substantial amounts of trace hazardous elements have been detected in industrial wastewater (e.g fluoride > 900 mg/L). Feed water characteristics, operational parameters, and membrane properties are major factors affecting flux and rejection of the MD process. Membrane parameters such as membrane material type and pore size have been investigated. Fluoride ion rejection was selected to setup a methodology to remove trace elements from wastewater by adjusting the membrane parameters in DCMD. Study of the fouling thickness of the MD membrane using pH and feed water composition revealed that a PVDF membrane with a smooth surface holds a thicker fouling layer, which enhances fluoride rejection while reducing the permeate flux. On the other hand, PTFE and PP membranes showed higher mass transfer and higher wetting performance, respectively. Therefore,a PVDF membrane with low organic feed water at higher alkaline pH can be utilized to obtain high-quality permeate, while PTFE can provide the highest flux with acceptable permeate water quality. Therefore, this methodology can be applied toidentify the optimum membrane to fit the required permeate flux, rejection requirements,and operating pH to treat any kind of non-volatileinorganic pollutants from industrial wastewater.

Anti-fouling graphene-based membranes for effective water desalination.

The inability of membranes to handle a wide spectrum of pollutants is an important unsolved problem for water treatment. Here we demonstrate water desalination via a membrane distillation process using a graphene membrane where water permeation is enabled by nanochannels of multilayer, mismatched, partially overlapping graphene grains. Graphene films derived from renewable oil exhibit significantly superior retention of water vapour flux and salt rejection rates, and a superior antifouling capability under a mixture of saline water containing contaminants such as oils and surfactants, compared to commercial distillation membranes. Moreover, real-world applicability of our membrane is demonstrated by processing sea water from Sydney Harbour over 72 h with macroscale membrane size of 4 cm2, processing ~0.5 L per day. Numerical simulations show that the channels between the mismatched grains serve as an effective water permeation route. Our research will pave the way for large-scale graphene-based antifouling membranes for diverse water treatment applications.

Hierarchical Composite Membranes with Robust Omniphobic Surface Using Layer-By-Layer Assembly Technique.

In this study, composite membranes were fabricated via layer-by-layer (LBL) assembly of negatively charged silica aerogel (SiA) and 1H,1H,2H,2H-perfluorodecyltriethoxysilane (FTCS) on a polyvinylidene fluoride phase inversion membrane and interconnecting them with positively charged poly(diallyldimethylammonium chloride) (PDDA) via electrostatic interaction. The results showed that the PDDA-SiA-FTCS coated membrane had significantly enhanced the membrane structure and properties. New trifluoromethyl and tetrafluoroethylene bonds appeared at the surface of the coated membrane, which led to lower surface free energy of the composite membrane. Additionally, the LBL membrane showed increased surface roughness. The improved structure and property gave the LBL membrane an omniphobic property, as indicated by its good wetting resistance. The membrane performed a stable air gap membrane distillation (AGMD) flux of 11.22 L/m2 h with very high salt rejection using reverse osmosis brine from coal seam gas produced water as feed with the addition of up to 0.5 mM SDS solution. This performance was much better compared to those of the neat membrane. The present study suggests that the enhanced membrane properties with good omniphobicity via LBL assembly make the porous membranes suitable for long-term AGMD operation with stable permeation flux when treating challenging saline wastewater containing low surface tension organic contaminants.