Advancements in Sustainable Membrane Technologies for Enhanced Remediation and Wastewater Treatment: A Comprehensive Review

Environmental contamination, a consequence of diverse anthropogenic activities, has emerged as a global concern, critically impacting ecosystems and human health. The sources of environmental pollutants are manifold, leading to the introduction of harmful substances into various ecological compartments. Air pollution, attributable to emissions from vehicular, industrial, and power generation activities, is characterized by the release of particulate matter, nitrogen oxides, sulfur dioxide, carbon monoxide, and volatile organic compounds. These pollutants are known to compromise air quality and pose substantial health risks. In aquatic environments, pollution manifests through industrial effluents, agricultural runoff laden with pesticides and fertilizers, mismanagement of waste, and untreated sewage, thereby threatening aquatic life, ecosystems, and human health [1]. Soil contamination, resulting from chemical spills, industrial waste disposal, mining activities, and agrochemical applications, leads to the accumulation of heavy metals, hydrocarbons, and other toxicants, adversely affecting soil health, plant growth, and groundwater quality. The prevalence of plastic pollution, exacerbated by the excessive use and improper disposal of plastic products, is evident in terrestrial and aquatic ecosystems, posing significant threats to wildlife. Radioactive contamination, arising from nuclear power plant accidents, inappropriate disposal of radioactive waste, and nuclear testing, impacts soil, water, and biota. Urbanization and industrialization contribute to noise pollution, with detrimental effects on human and wildlife health. Additionally, light pollution, stemming from excessive artificial nocturnal lighting, disrupts natural ecosystems, wildlife behavior, and human health. Thermal pollution, characterized by the discharge of heated industrial effluents into natural water bodies, alters the thermal regimes of aquatic ecosystems, negatively impacting species adapted to specific temperature ranges. These diverse forms of environmental contamination underscore the multifaceted nature of human-induced environmental impacts, leading to ecological degradation, health issues, and biodiversity loss [1].

In the context of escalating environmental pollution, remediation and wastewater treatment have become paramount in mitigating pollution and preserving ecological integrity. The pursuit of sustainable methods in these areas is increasingly recognized as vital for ensuring long-term environmental resilience and societal well-being [1]. The accumulation of contaminants, including heavy metals, pesticides, pharmaceuticals, microplastics, and emergent pollutants such as per- and polyfluoroalkyl substances (PFAS), is a direct consequence of industrial, agricultural, and waste management practices [2]. These contaminants, pervasive in the environment, pose significant threats to ecosystem health, leading to soil degradation, water contamination, and loss of biodiversity. Furthermore, their persistent nature raises concerns regarding human health, being implicated in various diseases, congenital anomalies, and other health complications [3], [4].

Traditionally, remediation practices have predominantly focused on containment and removal of pollutants, often neglecting considerations of long-term environmental sustainability. Sustainable remediation, in contrast, adopts a holistic approach that integrates environmental, social, and economic facets, aiming to minimize the ecological footprint of remediation activities while enhancing their beneficial impacts. Through considerations such as energy efficiency, material utilization, and the preservation of ecosystem services, sustainable remediation offers more environmentally sound solutions [4].

The treatment of wastewater, essential for the removal of contaminants from domestic, industrial, and agricultural effluents prior to their environmental release, traditionally relies on methods that, while effective, often entail high energy consumption and generate substantial sludge and waste. Sustainable approaches in wastewater treatment emphasize resource recovery, energy efficiency, and reducing environmental impacts of treatment processes. Innovations such as membrane filtration, anaerobic digestion, and the use of constructed wetlands are increasingly being employed for sustainable wastewater management [5].

The discharge of contaminants into the environment, whether through industrial effluents or untreated sewage, poses serious threats to ecosystems. Heavy metals, for instance, can bioaccumulate in aquatic organisms, disrupting physiological processes and diminishing biodiversity. The presence of pesticides and pharmaceuticals in aquatic systems can impair the growth and survival of aquatic organisms. Microplastics, defined as small plastic particles, are ingested by marine life, potentially entering the food chain and causing broad ecological disturbances [6].

Human health risks associated with contaminated water sources are significant. Ingestion of polluted water can lead to acute and chronic health impacts, contingent upon the nature and concentration of the contaminants. High levels of heavy metals such as lead and mercury are linked to neurological damage, developmental disorders, and organ dysfunction. Pharmaceuticals and endocrine-disrupting chemicals in water sources are associated with reproductive disorders and hormonal disturbances [7].

In addressing environmental pollution and its ramifications, sustainable remediation and wastewater treatment provide comprehensive solutions. These approaches strive to curtail the release of pollutants into the environment, diminish resource consumption, and enhance resource recovery. The implementation of sustainable practices, encompassing green remediation strategies, the utilization of renewable energy sources, and the adoption of circular economy principles in wastewater treatment, can significantly mitigate the adverse impacts of pollution, contributing to a healthier environment and improved human well-being [8].

The threat posed by environmental pollution to ecosystems and human health underscores the necessity of sustainable practices in remediation and wastewater treatment. By encompassing environmental, social, and economic considerations, these approaches offer effective solutions while reducing detrimental effects on ecosystems and human welfare. The adoption of these sustainable practices heralds a future where pollution is effectively managed, and environmental resources are conserved for future generations.

Membrane technology, recognized for its efficiency, versatility, and cost-effectiveness, has become a pivotal approach in wastewater treatment. The core principle of this technology, membrane separation, relies on size exclusion, molecular diffusion, and electrostatic interactions for effective contaminant removal. In membrane separation, size exclusion is the primary mechanism where contaminants are selectively retained or passed based on their size. The membrane serves as a physical barrier, permitting the passage of smaller molecules or particles, while larger contaminants are retained. The pore size of the membrane is critical in determining the effectiveness of separation, with contaminants larger than the pore size being rejected [9].

Molecular diffusion is another key principle in membrane separation. This process entails the movement of solutes from a region of higher concentration to a lower concentration. Within the context of wastewater treatment, dissolved contaminants in the feed solution diffuse across the membrane, driven by the concentration gradient, leading to their separation [10], [11].

Electrostatic interactions are integral in specific membrane separation processes like electrodialysis and membrane capacitive deionization. These methods employ ion-selective membranes, allowing the passage of ions based on their charge. Electrostatic forces facilitate the attraction or repulsion of ions, aiding in their separation. The application of an electric potential across the membrane allows for the selective transport of ions, thus contributing to the removal of charged contaminants [12].

The pore size and molecular weight cut-off (MWCO) of the membrane are decisive in determining the efficiency of separation in wastewater treatment applications. An appropriate membrane pore size is essential for efficient separation, based on the size of the contaminants in the wastewater. For example, microfiltration (MF) membranes, with larger pore sizes $(0.1-10 \mu \mathrm{m})$, are effective for removing suspended solids, bacteria, and larger particles. UF membranes, featuring smaller pore sizes $(0.001-0.1 \mu \mathrm{m})$, can remove viruses, proteins, colloids, and macromolecules. NF and RO membranes, with even smaller pore sizes $(0.001-0.001 \mu \mathrm{m})$, are capable of removing salts, small organic molecules, and some heavy metals [13].

MWCO, indicative of the molecular weight threshold for solute retention, is a vital parameter for membrane selection based on the specific separation requirements. The MWCO is determined by the membrane's pore size distribution and the molecular weight of the solutes. Selecting a membrane with the appropriate MWCO ensures the efficient separation and removal of specific contaminants, allowing for the retention of pollutants while enabling the passage of treated water [14].

Membrane technologies have significantly advanced diverse sectors, including water treatment, pharmaceuticals, and food processing. These technologies employ membranes of varied types to segregate contaminants based on size, molecular weight, and other properties. An overview of four principal membrane processes, namely, MF, UF, NF, and RO, is provided, elucidating the differences in their pore sizes, operating pressures, and separation capabilities, thereby illuminating their distinct applications.

MF employs membranes characterized by relatively large pore sizes, typically within the range of 0.1 to $10 \mu \mathrm{m}$. This process is principally engaged in the removal of suspended solids, bacteria, and larger particles from liquid streams. MF is effective in extracting bacteria such as Escherichia coli (E. coli), indicative of fecal contamination in water sources, Salmonella spp., prevalent in soil, water, and the gastrointestinal tracts of animals, Legionella pneumophila, the causative agent of Legionnaires' disease, Pseudomonas aeruginosa, often encountered in soil, water, and healthcare environments, Campylobacter spp., associated with foodborne illnesses, and Enterococcus spp., indicative of fecal matter contamination in water [15]. Operated at relatively low pressures, typically under 2 bar (30 psi), the membrane serves as a physical barrier, facilitating the passage of smaller particles while retaining larger ones. Applications of MF are widespread, encompassing water treatment, wastewater reclamation, and the food and beverage industry [15].

UF, utilizing membranes with smaller pore sizes compared to MF, features pore sizes ranging from 0.001 to $0.1 \mu \mathrm{m}$. UF is adept at removing macromolecules, colloids, proteins, and viruses from liquid streams. It is effectively used for the extraction of various viruses, including Hepatitis A virus (HAV), transmitted via contaminated food or water, Norovirus, responsible for gastrointestinal illnesses, Rotavirus, causing severe diarrhea in children, Adenovirus, linked to respiratory and other infections, and Enteroviruses, associated with a range of conditions from colds to more severe diseases like meningitis and myocarditis [16]. UF operates at slightly elevated pressures compared to MF, typically in the range of 1 to 10 bar (15-150psi), and finds applications in diverse fields such as water and wastewater treatment, dairy processing, biotechnology, and the pharmaceutical industry [16].

NF, a membrane process, serves as an intermediate between UF and RO in terms of pore size and separation capacity. NF membranes, characterized by their smaller pore sizes typically ranging from 0.001 to $0.01 \mu \mathrm{m}$, facilitate the removal of divalent ions, organic molecules, and certain monovalent ions. This process is notably effective in extracting various contaminants, including divalent salts such as calcium, magnesium, and sulfate ions, specific organic compounds like pesticides and some dyes, and heavy metal ions including lead, mercury, and cadmium, leveraging its size exclusion properties. In addition, NF is adept at removing bacteria [17]. Operated within the pressure range of 10 to 30 bar (150-450 psi), NF finds widespread application in water softening, color and odor removal, desalination, and selective separation of specific ions [17].

RO employs membranes with the smallest pore sizes among the discussed membrane processes, typically below $0.001 \mu \mathrm{m}$. RO is highly effective in eliminating salts, small organic molecules, and other dissolved contaminants. Operating at high pressures, typically between 20 to 100 bar (300-1500psi), RO overcomes osmotic pressure to achieve efficient separation. It is extensively utilized in applications such as desalination, production of ultrapure water, water reuse, and concentration of various solutions [18].

Collectively, membrane processes including MF, UF, NF, and RO provide versatile solutions for a wide array of separation needs. These processes are distinguished by their pore sizes, operating pressures, and separation capabilities, which enable the effective removal of contaminants of varying sizes and properties. Understanding the distinct characteristics of these membrane processes is crucial for their optimal selection and application in industries like water treatment, food processing, and pharmaceutical manufacturing. The differences in pore sizes, operating pressures, and separation capabilities among various membrane processes, namely MF, UF, NF, and RO. This comparison is encapsulated in Table 1.

The efficacy of membrane technology hinges on the appropriate selection of membrane materials, which are pivotal for efficient separation processes. This section delves into the common types of membrane materials, including polymeric, ceramic, and composite membranes, examining their merits and limitations. Additionally, various configurations of membranes such as flat sheet, tubular, spiral-wound, and hollow fiber are explored, each distinguished by unique characteristics and specific applications.

Polymeric membranes, prevalent due to their adaptability, cost-effectiveness, and ease of production, are generally fabricated from synthetic polymers like polyethylene, polypropylene, polyvinylidene fluoride (PVDF), and polysulfone. These membranes are noted for their high flux rates, commendable chemical resistance, and adjustable separation attributes. However, constraints in thermal and mechanical stability and susceptibility to fouling and degradation under strenuous conditions are noted drawbacks [16]. Advantages include cost-effectiveness, versatile separation properties, and high flux rates with good chemical resistance, while limitations encompass restricted thermal and mechanical robustness and a higher propensity for fouling and degradation in harsh environments.

Ceramic membranes are distinguished by their exceptional thermal and chemical stability, rendering them suitable for demanding applications. Constructed from inorganic materials like alumina, zirconia, and titania, they exhibit high mechanical strength, resistance to fouling, and durability under elevated temperatures and varied pH levels. Nonetheless, they are typically more costly to produce, exhibit lower flux rates in comparison to polymeric membranes, and often necessitate pretreatment owing to their limited pore size distribution [19]. Advantages include superior thermal and chemical stability, robust mechanical strength, and fouling resistance, while limitations comprise higher production costs, reduced flux rates relative to polymeric membranes, and potential need for pretreatment due to a narrow pore size range.

Composite membranes amalgamate different materials' benefits to surmount the limitations inherent in singular membrane types. They consist of a thin, active layer supported by a porous substrate, where the active layer is usually polymeric and the substrate may be either polymeric or ceramic. Composite membranes are recognized for their enhanced mechanical strength, flux rates, and selectivity compared to solely polymeric membranes, finding applications in water treatment and gas separation [20]. Advantages include augmented mechanical strength and selectivity, superior flux rates over pure polymeric membranes, and improved performance through material combination. Limitations involve a more intricate fabrication process compared to pure polymeric membranes.

Flat sheet membranes, comprising a thin, planar layer supported by a porous substrate, are primarily utilized in laboratory-scale experiments and small-scale applications, as well as components in composite membranes. Noted for their simplicity in design and ease of replacement, these membranes, however, are more prone to fouling owing to their extensive surface area [21].

Tubular membranes, characterized by their cylindrical shape with the membrane material lining the interior surface of the tube, are employed in scenarios demanding high mechanical strength and suitability for high-pressure operations. These membranes exhibit enhanced resistance to fouling and are prevalently used in industrial processes, including wastewater treatment and gas separation [22].

Spiral-wound membranes are constructed from flat sheet membranes wound spirally, creating permeate channels between adjacent layers. Favored in large-scale applications due to their compact design, high packing density, and scalability, they are frequently utilized in sectors like water desalination, food processing, and pharmaceuticals [23].

Hollow fiber membranes, distinguished by their elongated, cylindrical configuration with a porous membrane wall encircling a hollow interior, are known for their high surface area-to-volume ratio. These membranes are optimally suited for applications requiring elevated flux rates and are employed across diverse fields, including water treatment, biomedical devices, and gas filtration [23].

Groundwater contamination constitutes a significant threat to both environmental and human health. Traditional remediation techniques typically entail excavation and off-site treatment, approaches that are often both costly and time-consuming. As an alternative, membrane processes have emerged as a promising solution for in-situ groundwater treatment, facilitating the effective removal of contaminants such as volatile organic compounds (VOCs) and heavy metals.

In particular, membrane processes like RO and NF have demonstrated potential in the extraction of VOCs from groundwater. These processes operate based on the selective permeation principle, where water molecules are allowed to pass through while dissolved contaminants are rejected. This rejection is based on factors such as molecular size, charge, and solubility of the contaminants. Membranes designed with specific properties, including high rejection rates and robust chemical resistance, are effectively employed in removing a broad spectrum of VOCs, encompassing chlorinated solvents and aromatic compounds [24].

Similarly, membrane technology has been applied to the removal of heavy metals from groundwater. Processes including RO, UF, and electrodialysis reversal (EDR) have shown efficacy in the separation and concentration of heavy metal ions. The utilization of selective membranes, tailored for specific contaminants, enables the rejection of metal ions while permitting water molecules to pass through, offering a sustainable approach to mitigating heavy metal contamination [25].

In various studies, the application of RO for VOC removal in groundwater contaminated with chlorinated solvents has been investigated, demonstrating removal efficiencies exceeding 99% for various VOCs, thereby underscoring the effectiveness of RO in groundwater remediation [26] likewise the use of UF membranes for heavy metal removal in groundwater contaminated with lead and cadmium, achieving significant removal efficiencies (>95 %) for both metals, highlighting the potential of UF in heavy metal remediation [27].

Enhanced selectivity: Membrane processes exhibit heightened selectivity in contaminant separation from water. The controlled pore size and charge characteristics of membranes facilitate selective pollutant rejection, ensuring high-quality treated water. This selectivity diminishes the need for additional treatment steps, rendering membrane processes more efficient and cost-effective [28].

Minimal chemical additive use: Contrasting traditional groundwater treatment methods that frequently rely on chemical additives, membrane processes primarily depend on physical separation mechanisms. This minimizes chemical usage, reducing environmental impacts and the potential formation of harmful by-products, thus promoting a sustainable approach to groundwater remediation [29].

In-situ treatment: Membrane processes enable in-situ groundwater treatment, as systems can be directly installed in subsurface environments. This approach minimizes site disturbances, reduces costs, and facilitates real-time monitoring and control of the remediation process [30].

Versatility and scalability: These processes offer versatility and scalability, suitable for diverse groundwater remediation scenarios. Membranes can be customized for specific contaminants, and their modular design allows for adjustments and expansions as per site requirements, making them applicable for both small and large-scale remediation projects [31].

The critical role of municipal wastewater treatment in safeguarding public health and environmental integrity has been increasingly addressed through advancements in technology, including the adoption of membrane processes. Membrane filtration, notable for its capacity to effectively remove suspended solids, pathogens, and micropollutants, has garnered significant attention in wastewater management [32].

The challenge of suspended solids in wastewater, which can cause blockages and ecological disturbances, is effectively mitigated by membrane filtration. MF and UF membranes, in particular, demonstrate high effectiveness in solids removal while maintaining low transmembrane pressure. This efficiency enhances the performance of wastewater treatment facilities by improving solids separation and reducing the burden on subsequent treatment stages [33].

Pathogens in wastewater represent a substantial public health risk. Traditional treatment methods such as sedimentation and disinfection are often limited in pathogen removal efficacy. Membrane processes, leveraging their small pore sizes and barrier properties, offer superior pathogen removal. UF and NF membranes, capable of filtering a broad spectrum of pathogens including bacteria, viruses, and protozoa, serve as effective physical barriers. This results in the production of high-quality effluent that conforms to stringent regulatory standards for discharge or reuse [34].

The presence of micropollutants, encompassing pharmaceuticals, pesticides, and endocrine-disrupting compounds, poses a significant challenge for conventional wastewater treatment methods. Membrane processes, particularly NF and RO, have demonstrated promising capabilities in micropollutant removal. Utilizing mechanisms of size exclusion and charge-based rejection, these membranes significantly reduce micropollutant concentrations in effluent [35].

Membrane filtration offers several advantages over conventional wastewater treatment methods. It ensures consistent and reliable containment of contaminants, yielding a higher treatment efficiency. Membranes achieve superior removal rates of suspended solids, pathogens, and micropollutants, thereby enhancing water quality. Furthermore, membrane filtration enables precise process control and monitoring, as evidenced by real-time measurements of key parameters like transmembrane pressure and flux [36].

The compact footprint and modular design of membrane processes render them adaptable for both centralized and decentralized wastewater treatment systems. The production of high-quality effluent through membrane filtration facilitates water reuse, a critical consideration in water-scarce regions. Membrane technology, in producing reclaimed water that meets rigorous quality standards, contributes to reducing dependence on freshwater resources [37].

MBRs, an advanced technology in wastewater treatment, have garnered increasing attention due to their ability to enhance treatment efficiency and produce superior effluent quality [38]. MBRs represent a synergistic integration of biological processes with membrane filtration, distinct from traditional activated sludge systems where a clarifier or settling tank separates biomass from treated water. In MBRs, the membrane module serves as the solid-liquid separation unit, eliminating the need for secondary clarifiers. The membrane, acting as a physical barrier, permits the passage of water and dissolved substances while retaining suspended solids, microorganisms, and particulate matter [39].

The fusion of biological treatment with membrane filtration in MBRs offers several benefits. A pivotal advantage is the efficient solid-liquid separation achieved by the membrane, resulting in a higher biomass concentration within the system. This elevated biomass concentration enhances treatment efficiency as microorganisms have extended contact time with wastewater, leading to more effective pollutant removal [40]. Additionally, MBRs provide improved control over hydraulic retention time (HRT) and solids retention time (SRT), critical parameters in wastewater treatment. The HRT can be modulated by adjusting the filtration rate, optimizing treatment processes, while the increased SRT, owing to higher biomass concentration, augments the degradation of organic matter and nutrient removal [38].

MBRs exhibit several advantages over conventional wastewater treatment methods. Notably, the higher biomass concentration in MBRs allows handling of increased organic loads, yielding a more efficient treatment process. This capacity also enables MBRs to adapt to varying flow rates and pollutant loadings, enhancing their flexibility [39], [40]. Additionally, MBRs significantly reduce sludge production. As the membrane retains biomass, minimal sludge loss occurs during solid-liquid separation, decreasing waste generation and associated handling and disposal costs [41].

Furthermore, MBRs produce effluent of markedly superior quality compared to traditional methods. The membrane effectively removes suspended solids, pathogens, and a wide range of pollutants, ensuring effluent compliance with stringent regulatory standards for discharge or reuse. This improved effluent quality renders MBRs suitable for diverse applications, including water reuse and irrigation, particularly in environmentally sensitive areas. The compact design of MBRs, resulting in a smaller footprint, is advantageous for both centralized and decentralized wastewater treatment facilities. Their modular nature facilitates easy expansion or retrofitting, accommodating future growth and population increases [40], [41].

Hollow fiber membranes, characterized by their elongated, cylindrical shape and a porous membrane wall that encloses a hollow core, are distinguished for their high surface area-to-volume ratio. This unique design renders them particularly suitable for applications necessitating high flux rates. Employed extensively in both liquid and gas separations, hollow fiber membranes are integral to a variety of applications. These include water treatment processes, biomedical devices, and gas filtration [23].

While membrane technology has significantly impacted various sectors, notably in water and wastewater treatment, it faces several challenges and limitations. These include fouling, scaling, high energy consumption, and membrane degradation, which can compromise efficiency and sustainability.

Fouling represents a primary challenge in membrane applications. It is characterized by the accumulation of particles, microorganisms, and organic matter on the membrane surface or within its pores, leading to reduced permeability and operational efficiency. This accumulation necessitates increased energy usage, frequent cleaning or replacement of membranes, and ultimately shortens membrane lifespan. Scaling, another significant challenge, involves the precipitation of inorganic salts on the membrane surface, which impedes permeability and performance. The prevention and management of scaling are critical for maintaining the efficiency of membrane processes [42].

High energy consumption is a notable limitation, primarily due to the transmembrane pressure required to counteract fouling and achieve desired flux rates. Additionally, the energy demands of pumping and aeration systems, essential for maintaining fluid flow and oxygenation in wastewater treatment, contribute to the overall energy footprint of membrane technologies. This energy-intensive nature raises concerns about the cost-effectiveness and environmental sustainability of membrane-based processes [42].

Membrane degradation, resulting from exposure to harsh wastewater conditions such as extreme pH levels, high temperatures, and chemical interactions, poses another challenge. Degradation affects membranes' permeability, structural integrity, and selectivity, necessitating frequent replacements and thus increasing operational costs and waste generation [42].

Affordability remains a constraint for the widespread adoption of membrane technology, particularly in developing countries or regions with limited financial resources. The high initial capital cost and ongoing operational expenses, including membrane replacement, cleaning, and energy consumption, can be prohibitive.

Large-scale implementation also presents challenges, especially regarding space requirements for pre-treatment, post-treatment, and membrane modules. This can be particularly problematic in urban areas where space is limited. Scaling up membrane systems may require infrastructure modifications and the development of suitable management and operational strategies [43].

Lastly, the selectivity and efficiency of membranes in removing specific contaminants vary. While effective in removing suspended solids, pathogens, and many dissolved constituents, membranes may exhibit limitations in filtering certain organic compounds, heavy metals, and emerging contaminants. The material, pore size, and molecular weight cutoff of the membrane influence its selectivity and removal efficiency for different contaminants [43].

To address the prevalent challenges in membrane technology, a multifaceted approach is essential. A primary strategy involves the implementation of effective pre-treatment processes to mitigate fouling and scaling. These processes, including coagulation, adsorption, and oxidation, aim to reduce the concentration of potential foulants and scalants in the feed water, thereby enhancing membrane performance. Furthermore, the adoption of optimized cleaning protocols, such as backwashing, chemical cleaning, and air scouring, plays a crucial role in removing accumulated substances from the membrane surface [44].

Innovation in membrane design and material composition is another key strategy. Surface modifications, such as hydrophilic coatings and the introduction of nanocomposite materials, are being explored to reduce the propensity for fouling and scaling. The integration of antimicrobial agents or nanoparticles into the membrane matrix can also significantly mitigate biofouling, thus improving membrane longevity and effectiveness [44].

Enhancing energy efficiency in membrane systems is achieved through advanced module design and system optimization. The development of low-energy membrane technologies, such as forward osmosis and pressure-retarded osmosis, harnesses osmotic pressure gradients to decrease energy consumption. Additionally, optimizing operational parameters, including membrane flux rates, transmembrane pressure, and aeration rates, contributes to the reduction of energy requirements in membrane processes [44].

Current research and development efforts in membrane technology focus on overcoming its inherent challenges and expanding its applications. Novel membrane materials, such as graphene oxide and advanced ceramic membranes, are under investigation for their enhanced durability, selectivity, and resistance to fouling. Surface modification techniques, including plasma treatment and functionalization, are being studied to improve membrane resistance to fouling and scaling [45].

Efforts to enhance the energy efficiency of membrane processes are ongoing. This includes the exploration of renewable energy sources, such as solar and wind power, for operating membrane systems. The integration of membrane technology with other treatment processes, such as adsorption and advanced oxidation, is also being researched to boost overall efficiency and effectiveness in contaminant removal [45].

As membrane technology continues to evolve, driven by the imperative for more sustainable and efficient water and wastewater treatment solutions, identifying key areas for future research is crucial. A primary area of focus is the development of sustainable membrane materials. Conventional polymeric membranes, while widely utilized, exhibit limitations in fouling resistance, selectivity, and environmental impact. Future research is directed toward novel materials, including bio-based polymers like cellulose and chitosan, derived from renewable resources, offering sustainable alternatives. The integration of nanomaterials such as graphene oxide and carbon nanotubes into membranes presents opportunities to enhance performance and selectivity [46].

Derived from graphene, graphene oxide exhibits outstanding mechanical strength. Its incorporation into membrane structures significantly enhances their robustness and stability. The distinctive two-dimensional structure of graphene oxide, characterized by nanopores and functional groups, augments selectivity in molecular and ionic separation. This structure facilitates selective permeation, allowing certain substances to pass while obstructing others, thereby improving the membrane's separation capabilities. Additionally, the rapid and efficient transport of water molecules is enabled by graphene oxide, while larger ions or molecules are effectively blocked, enhancing the membrane's permeability. The surface chemistry of graphene oxide can be tailored through functionalization, permitting selective interactions with specific molecules or ions and thus further enhancing selectivity. Carbon Nanotubes (CNTs), with their tubular structure and high aspect ratios, provide efficient pathways for water molecule movement, contributing to increased membrane permeability [47]. These nanotubes serve as nanochannels, facilitating swift flow of water or selected ions through the membrane, thereby enhancing transport properties. CNTs, similar to graphene oxide, can undergo surface functionalization to modify their properties, allowing for selective interactions with specific molecules or ions, which enhances membrane selectivity. When embedded within the membrane matrix, CNTs contribute to improved mechanical strength and structural integrity, reducing fouling and extending the membrane's lifespan. When graphene oxide and carbon nanotubes are integrated into membrane structures, often in conjunction with polymeric or ceramic matrices, they induce synergistic effects. These effects manifest as enhanced permeability, selectivity, and mechanical strength, leading to significant improvements in membrane performance. The incorporation of these nanomaterials results in membranes that exhibit higher flux rates, better resistance to fouling, improved selectivity for specific molecules or ions, and greater durability compared to conventional membranes. Such advancements hold substantial promise for broad applications, including water treatment, desalination, purification, and various separation processes [48].

Addressing fouling, a significant challenge in membrane technology, is a key area for future advancements. Exploring innovative anti-fouling coatings, such as zwitterionic and superhydrophilic materials, can diminish foulant adhesion and enhance flux. The development of novel anti-fouling strategies, including biofilm control, enzymatic cleaning, and bio-inspired surface modifications, are of high research interest. Additionally, integrating advanced monitoring and control systems, capable of real-time fouling detection and adaptive control, is vital for effective fouling management [49].

Process optimization is another critical research avenue. Advanced modeling and simulation tools are essential for optimizing membrane processes, including determining optimal operating conditions and configurations. The application of artificial intelligence and machine learning in real-time monitoring and adaptive operation is poised to enhance energy efficiency and overall system performance. Research into hybrid membrane systems, combining various membrane processes or integrating membrane technology with other treatment methods, promises to augment efficiency and efficacy [50].

Interdisciplinary collaborations and knowledge exchange are essential for the continued advancement of membrane technology. Collaborative efforts among materials science, chemistry, biology, engineering, and environmental science researchers can drive innovation and accelerate development. Partnerships between academia, industry, and government agencies are crucial for bridging the research-implementation gap, facilitating technology transfer and commercialization [51], [52].

Knowledge dissemination platforms, such as conferences and research networks, are instrumental in promoting collaboration and innovation. These forums allow researchers to share findings, establish networks, and access open-access journals and databases, fostering broader knowledge dissemination and innovation in membrane technology [52].

Membrane technology has emerged as a pivotal contributor to resource recovery, facilitating the extraction of valuable components from wastewater, thereby promoting sustainable water management and environmental protection. Through membrane filtration processes, such as UF, effective separation of organic and inorganic nutrients, including nitrogen and phosphorus, from wastewater is achieved. These nutrients can be subsequently reclaimed for agricultural or other applications. Additionally, RO is utilized to concentrate nutrients from diverse sources like agricultural runoff or organic waste streams, enabling the extraction of nutrient-rich solutions by separating water from these nutrients. The integration of biological treatment with membrane separation in membrane biofilm reactor systems has been instrumental in extracting biogas, primarily methane, from wastewater treatment processes. This biogas serves as a valuable source of energy. Moreover, membrane-based wastewater treatment processes, exemplified by MBRs, efficiently separate pollutants, yielding treated water that adheres to stringent quality standards for reuse in various non-potable applications. This approach aligns with the principles of a circular economy, reducing waste generation and enhancing the overall sustainability of the treatment process.

However, membrane technology faces challenges and limitations, such as fouling, scaling, high energy consumption\hyphenpenalty=10000, and membrane degradation, which necessitate ongoing attention to optimize performance and cost-effectiveness. Current research endeavors are directed towards developing sustainable membrane materials, innovative fouling control methods, and optimizing process strategies. In conclusion, membrane technology holds significant promise for sustainable remediation and wastewater treatment. It offers a pathway towards efficient water management, environmental protection, and resource recovery. To fully realize the potential of membrane technology in addressing global water challenges, continued research, innovation, and collaboration among scientists, industry professionals, and policymakers are imperative.