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Article

Techno-Economic Assessment (TEA) of a Minimal Liquid Discharge (MLD) Membrane-Based System for the Treatment of Desalination Brine

by
Argyris Panagopoulos
School of Chemical Engineering, National Technical University of Athens, 9 Iroon Polytechniou St., Zografou, 15780 Athens, Greece
Separations 2025, 12(9), 224; https://doi.org/10.3390/separations12090224
Submission received: 24 July 2025 / Revised: 19 August 2025 / Accepted: 20 August 2025 / Published: 23 August 2025
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Abstract

Desalination plays a critical role in addressing global water scarcity, yet brine disposal remains a significant environmental challenge. This study evaluates a minimal liquid discharge (MLD) membrane-based system integrating high-pressure reverse osmosis (HPRO) and membrane distillation (MD) for brine treatment, with a focus on the Eastern Mediterranean. A techno-economic assessment (TEA) was conducted to analyze the system’s feasibility, water recovery performance, energy consumption, and cost-effectiveness. The results indicate that the hybrid HPRO-MD system achieves a high water recovery rate of 78.65%, with 39.65 m3/day recovered from MD and 39 m3/day from HPRO. The specific energy consumption is 23.2 kWh/m3, with MD accounting for 89% of the demand. The system’s cost is USD 0.99/m3, generating daily revenues of USD 228 in Cyprus and USD 157 in Greece. Compared to conventional brine disposal methods, MLD proves more cost-effective, particularly when considering evaporation ponds. While MLD offers a sustainable alternative for brine management, challenges remain regarding energy consumption and the disposal of concentrated waste streams. Future research should focus on renewable energy integration, advanced membrane technologies, and resource recovery through brine mining. The findings highlight the HPRO-MD MLD system as a promising approach for sustainable desalination and circular water resource management.

Graphical Abstract

1. Introduction

Water occupies an important position in sustainable development, as the revitalization of ecosystems, the provision of energy, and social development are all inextricably tied to its availability [1,2]. The nations of the Eastern Mediterranean, exemplified by the Hellenic Republic (i.e., Greece) and the Republic of Cyprus (i.e., Cyprus), are peculiarly prone to water scarcity due to their characterization as highly susceptible regions to climatic fluctuations [3,4]. A novel approach to addressing the global challenge of water scarcity is unfolding, as desalination technology seeks to tap into the virtually boundless resources of the world’s oceans [5,6,7,8,9].
The global desalination industry currently comprises over 21,000 operational facilities, which collectively yield nearly 140 million m3 of potable water every day [10]. While desalination processes provide a consistent source of freshwater, they also generate a secondary product (i.e., by-product), namely brine, concentrate, or reject, which is characterized as saline wastewater [11]. The brine in question presents substantial ecological concerns due to its elevated salinity (Table 1) and the likelihood of the presence of potential hazardous substances resulting from the residues of pretreatment processes. The salinity of brine hinges on a spectrum of several ions (Na+, Ca2+, Mg2+, Cl−, HCO3−, etc.) [12,13,14,15,16].
Brine effluent management necessitates the deployment of diverse disposal strategies by desalination facilities, encompassing the utilization of evaporation ponds, deep-well injection, conveyance to sewage systems, oceanic or surface water disposal, and terrestrial practices [17,18,19,20]. Regrettably, these disposal methods are accompanied by detrimental consequences for local ecosystems [21,22].
In recent years, environmental concerns surrounding saline wastewater discharge have driven the development of innovative approaches. Zero liquid discharge (ZLD) represents a paradigmatic approach to saline water valorization/treatment, which seeks to entirely eliminate wastewater discharge from facilities, thereby enabling the recovery of significant volumes of water for reuse and ensuring the responsible management/valorization of co-generated solid salt. Notably, nearly all freshwater is reclaimed through ZLD systems, wherein the resulting solid salt(s) can be valorized or disposed of in a significantly more environmentally friendly manner [23,24,25,26,27]. From a long-term perspective grounded in sustainability, the ZLD concept exhibits remarkable congruence with the fundamental tenets of the circular economy (CE) paradigm, rendering it an apt framework for the furtherance of desalination and brine management [28,29,30,31,32,33].
It is pertinent to note that the notion of minimal liquid discharge (MLD) also warrants consideration, as it shares a similar objective with ZLD, namely, to extract water while reducing the volume of effluent brine. However, there exist distinct differences between the two approaches. For instance, MLD exclusively relies on membrane-based technologies, which, in turn, result in a greater quantity of brine. The MLD approach, having garnered significant attention of late, has been found to necessitate substantially reduced energy and operational expenditure while concurrently achieving a remarkably high target for freshwater recovery [11,34].
In hybrid MLD systems, multiple desalination processes are consolidated, mirroring the configuration employed in ZLD systems. Notably, the reliance solely on membrane-based technologies in MLD systems yields notable benefits. In particular, the reduced energy and cost requirements of MLD systems can be ascribed to the fact that they predominantly employ membrane-based technologies, unlike ZLD schemes, which integrate both membrane- and thermal-based processes [10,35].
Membrane-based technologies encompass a diverse array of methods, including electrodialysis reversal (EDR), forward osmosis (FO), reverse osmosis (RO), membrane distillation (MD), and high-pressure RO (HPRO), amongst others [36,37,38,39,40]. The MLD framework operates within the paradigm of the circular economy model, a paradigm endorsed by the European Union (EU). This notion of sustainable development, as championed by the EU, suggests a departure from traditional linear practices, instead embracing a regenerative approach that favors recycling and reusing resources.
Regarding the desalination technologies, a small variety of technologies has been adopted. Notably, approximately 74% of the global desalination facilities employ RO technology due to its demonstrated energy efficiency. The existing generation of RO membranes and modules possesses the capacity to withstand pressures < 82 bar and tolerate salinities of up to 70 g/L [41]. Nevertheless, RO technology is not ideally suited for treatment of extremely saline streams. Advances in membrane technology have facilitated the creation of HPRO, a system capable of functioning at pressures of up to 160 bar, thereby allowing it to be effectively utilized for the desalination of brackish water/seawater as well as the treatment of brine. However, it should be mentioned that the standard RO membranes are not suitable for HPRO applications. Under the extreme hydraulic pressures of HPRO, these membranes undergo severe and irreversible compaction. This deformation leads to a densification of the membrane’s support and polyamide selective layers, resulting in a significant decline in water permeability and a potential loss of salt rejection due to the formation of defects on the selective layer. Therefore, HPRO requires specially engineered membranes with enhanced mechanical strength and structural integrity to withstand these harsh operating conditions and maintain performance [42,43,44,45].
Another membrane-based technology, MD, has emerged as a cutting-edge approach to desalination, leveraging the unique properties of hydrophobic membranes to transform saline water into treated water. By exploiting the thermodynamic gradient generated across the membrane, water vapor is translocated from the salty, hotter side to the more diluted, cooler side, thereby effecting the separation of water from its inorganic and organic impurities. A particularly attractive feature of MD is its energy efficiency, which enables operation at lower pressures/temperatures in comparison to traditional methods, such as RO. This technology has demonstrated exceptional efficacy in treating seawater and brine, which are inherently high-salinity sources, thereby rendering it a pragmatically viable solution to addressing global water scarcity. Furthermore, the modular design of MD facilitates effortless scalability, allowing it to cater to a wide range of desalination requirements, from large-scale industrial applications to localized village settings [46,47,48,49].
Despite the pervasive importance of brine treatment, a substantial amount of theoretical and empirical knowledge remains to be explored in regard to these topics. The existing corpus of research primarily centers on assessing the efficacy of MLD/ZLD systems that integrate conventional and well-established technologies. This research study introduces a novel approach by integrating HPRO and MD technologies within a MLD framework for the first time. This article represents a significant contribution to the peer-reviewed literature, as it explores the combination of HPRO and MD for effective brine valorization/treatment and resource extraction. Additionally, the computational study evaluates the feasibility and performance of this HPRO-MD hybrid system, focusing on brine management strategies. It also investigates the potential for implementing this MLD system in Eastern Mediterranean countries, specifically Greece and Cyprus. To achieve these goals, the techno-economic viability of the HPRO-MD MLD system is thoroughly analyzed for its effectiveness in treating and utilizing seawater brine. The selection of HPRO and MD for this MLD system is based on their complementary operational capabilities for treating hypersaline brines. While both technologies can be energy-intensive, their combination offers a strategic advantage. HPRO is one of the few membrane technologies capable of handling the high osmotic pressure of desalination brine to achieve significant initial water recovery [50]. The resulting HPRO reject, which is too saline for further pressure-driven membrane treatment, is an ideal feed for MD. MD is a thermally-driven process that is not limited by osmotic pressure and can treat brines to very high concentrations [46,51]. This synergy allows the hybrid system to achieve much higher overall water recovery than either technology could alone, which is the primary objective of an MLD strategy.
Table 1. Composition of brines from several industrial sectors [52].
Table 1. Composition of brines from several industrial sectors [52].
Industrial SectorTotal Dissolved Solids (TDS) (mg/L)
Petrochemical industry20,000–85,000
Desalination industry50,000–82,000
Aquaculture industry12,000–47,000
Textile industry1500–50,000
Pharmaceutical industry20,000–50,000

2. Materials and Methods

2.1. System Configuration

This study outlines a methodology designed to optimize water extraction, achieve MLD conditions, and manage brine generated from a desalination plant. The MLD treatment framework integrates two primary technologies, namely HPRO and MD. Figure 1 depicts the operational layout of the MLD system, highlighting the sequential progression of processes. Within this framework, seawater is initially introduced into the HPRO unit, where desalination occurs, yielding two outputs, namely brine and permeate. The permeate is reclaimed as freshwater, whereas the brine is conveyed to the MD unit. In the MD unit, both the desalted liquid (permeate) and the brine are collected. The combined freshwater output consists of HPRO permeate and MD permeate. A significant advantage of this system is its capacity to process saline water/wastewater, gradually reducing its volume, thus minimizing environmental impact while producing precious resources, such as drinking water. From a structural standpoint, the HPRO unit is placed as the first step in the MLD system due to its ability to handle feedwater with lower salinity levels compared to the MD unit. It is crucial to highlight that Figure 1 illustrates a conceptual process flow diagram for a computational model, not a schematic of a physical component. The techno-economic assessment methodology section that follows provides specifics on the technical factors that define this model, including operational pressures, flow rates, etc. This modeling technique, which is used for feasibility studies, enables the assessment of a system’s potential before it is physically constructed, which requires significant financial investment.

2.2. Techno-Economic Assessment (TEA) Methodology

This study conducts a detailed techno-economic assessment (TEA) and feasibility analysis to evaluate the technical/commercial potential of implementing the MLD system for seawater treatment. The research explores scalability prospects for deployment across the Eastern Mediterranean, specifically in Greece and Cyprus. A representative feedwater flow rate of 100 m3/day (ambient temperature and pressure) and salinity of 38.000 mg/L—consistent with regional seawater characteristics—were selected as baseline parameters [53]. A feedwater flow rate of 100 m3/day was selected as a representative baseline for a small-scale decentralized treatment facility, allowing for a scalable analysis applicable to various contexts. The HPRO operating pressure of 120 bar was chosen as it represents a realistic and challenging condition for treating hypersaline seawater RO brine, consistent with the upper operational limits of commercially available HPRO systems. For desalination plants to operate as efficiently as possible, the simulation is predicated on continuous operation. While the MD unit is modeled with a feed–permeate temperature differential of 40 °C (i.e., 60 °C feed, 20 °C permeate), which is a common working condition, the HPRO unit is designed to run at a pressure of up to 120 bar, a typical parameter for high-salinity applications. These predetermined parameters serve as the foundation for the reported performance results and are essential to the simulation’s integrity. Financial assumptions include a 5% interest rate and a 30-year operational lifespan to align with long-term infrastructure investments. Economic data on equipment and operational costs were compiled through vendor quotations, peer-reviewed publications, industry reports, and authoritative databases. Analytical methodologies and equations underpinning the assessment are summarized in Table S1 (Supplementary Material), while Table 2 delineates cost estimates, technical specifications, and assumptions derived from prior studies and verified sources. The fact that this study is a computational techno-economic evaluation must be denoted. Instead of constructing or operating a physical pilot system, the methodology focuses on developing a comprehensive model. The performance (such as energy consumption and water recovery) and cost of the suggested HPRO-MD system are simulated by this model under a specific set of assumptions. To make sure that the simulation offers a realistic and reliable assessment of the system’s viability, the data, equations, and parameters are carefully taken from the peer-reviewed literature, technical datasheets from equipment manufacturers, manufacturers’ offers, and well-known industry cost databases [24,53,54,55,56].

3. Results and Discussion

3.1. Water Recovery

In the desalination sector, the enhancement of water reclamation is crucial, as it allows for the recovery of larger quantities of potable water while simultaneously reducing wastewater disposal. Water recovery is calculated by dividing the volume of produced water by the total volume of feed water. The MLD system achieves an impressive water recovery rate of 78.65%, which is significantly valuable in relation to the maximum threshold in the MLD approach. In particular, the recovery rate is composed of 39.65 m3/day from MD and 39 m3/day from HPRO, with each technology contributing 50% to the overall recovery (Figure 2).
The water produced by this system meets potable water criteria, exhibiting TDS below 500 mg/L. A detailed ionic composition of the permeate is provided in the Supplementary Material. The MD unit, which operates on thermal principles, generates pure water (TDS < 50 mg/L). This substantial decrease in TDS is accomplished through the evaporation and condensation processes utilized in this technology. The availability of such pure water is particularly valuable in industrial sectors, like pharmaceuticals, where strict requirements necessitate minimal salinity levels.
In contrast, HPRO produces water with an increased TDS that can range from 450 mg/L to over 1000 mg/L [42]. The TDS of the HPRO permeate is principally determined by the membrane’s salt rejection capability [42,57,58,59]. Although HPRO demonstrates salt rejection of over 95%, various factors, such as fouling or extended operational periods, may reduce its efficiency, leading to a decrease in water purity. The extent of efficiency reduction in HPRO can vary based on specific conditions and the severity of encountered challenges. Observations indicate that this efficiency decline can vary from 2% to 10%. It is essential to recognize that it is a generic estimate, and the loss in the efficiency could vary [35,60,61,62,63].
Additionally, the replacement of the membranes is affected by water quality, effectiveness of pretreatment, conditions of the operation, and membrane integrity. Increased fouling issues or inadequate pretreatment can speed up degradation, necessitating more regular replacements. As a rule of thumb, the membrane replacement rate for the HPRO is estimated to range from 2% to 5% annually. This range (i.e., 2–5%) is widely accepted in techno-economic analyses of brackish water and seawater RO desalination plants and is substantiated by long-term operational data from full-scale facilities, which report on membrane longevity and replacement cycles under various feedwater qualities and pretreatment regimes [59,64,65]. Nevertheless, it is crucial to emphasize that the HPRO water quality is within a satisfactory range. The volume breakdowns of the MLD system’s end-product indicate that the permeate volumes from the HPRO unit (39 m3/day) and the MD unit (39.65 m3/day) are comparable, with each contributing roughly half of the total recovered water.

3.2. Energy and Cost Demands

In addition to the water recovery, energy demands represent a crucial factor when assessing the performance of MLD systems. The energy consumption of the hybrid MLD system is 23.2 kWh/m3, a competitive value that underscores the advantage of integrating HPRO and MD. This hybrid configuration strategically balances electrical and thermal energy inputs to optimize efficiency, thereby enhancing the overall sustainability of the system. The integration of these two technologies not only improves energy utilization but also contributes to reducing operational costs over time. Figure 3 illustrates the breakdown of energy demands across each MLD process, with the MD unit accounting for the majority at 89%, while the HPRO unit represents the lowest energy requirement at 11%. This significant disparity highlights the importance of optimizing the MD process to further enhance energy efficiency and reduce costs associated with energy consumption. Understanding these energy dynamics is essential for future advancements in MLD technology and for making informed decisions regarding system design and operation. Furthermore, it is important to include a preliminary analysis of the system’s carbon. Given the total specific energy consumption of 23.2 kWh/m3 and using a grid emission factor for the Eastern Mediterranean region (i.e., 0.256 kg CO2-eq/kWh for Greece) the estimated GHG emissions are 5.94 kg CO2-eq/m3 of produced water [56]. This analysis underscores the significant environmental benefit of integrating renewable energy sources to power the MLD system, a point that is now discussed in greater detail.
The assessment of costs is of paramount significance in the execution of desalination initiatives, serving as a vital element in the TEA. The cost of the MLD system is documented at USD 0.99/m3, a reasonable figure given the hybridization of two distinct technologies within the hybrid framework. To gain additional insight into the cost breakdown across the MLD processes, Figure 4 delineates the percentage breakdown of each technology. The MD process emerges as the most expensive element, accounting for 60% of the total cost demands, whereas the HPRO process represents a lesser expense, contributing 40%.
The MLD system presents numerous opportunities for the utilization of its output. The freshwater generated by this system can be applied in various residential and commercial contexts. Figure 5 provides an analysis of net revenue, which evaluates the economic viability and potential benefits of the MLD system. Notably, the MLD system generates the highest revenue in Cyprus, amounting to USD 228 per day, whereas Greece sees the lowest revenue at USD 157 per day. This variation in earnings can be credited to differences in water sale prices between the two countries. These valorization techniques are crucial from a techno-economic perspective because they offer prospective sources of income that could partially cover the brine treatment’s operating expenses. For instance, the recovery of valuable minerals turns brine from a liability that needs to be disposed of at great expense into an asset, increasing the MLD system’s overall viability and encouraging a desalination process that is genuinely circular.

3.3. Cost Comparison and Profitability

Figure 6 illustrates a comparative evaluation of the costs related to the MLD system and those associated with traditional water sources. The analysis reveals that water obtained from surface water sources demonstrates a cost reduction of at least 42.3% relative to the expenditures of the MLD system. In contrast, the financial outlay for water extracted from subsurface sources is nearly equivalent to that of the MLD system. It is worth noting that the costs of subsurface water extraction can exceed those of the MLD system, especially in scenarios where substantial well depths require considerable energy consumption for pumping activities. Furthermore, the expenses tied to subsurface water sources are influenced by various factors, such as permit requirements, distribution infrastructure, compliance with environmental regulations, and transportation systems. By offering water prices comparable to those of subsurface sources, MLD systems provide additional water resources and contribute to mitigating water scarcity. This is particularly beneficial for nations in the Mediterranean region, including Greece, where roughly one-quater of water supplies are sourced from subsurface [66,67].
Several alternatives for brine disposal are available, including evaporation ponds, discharge into sewage systems or surface water bodies, deep-well injection, and other methods. Nevertheless, these approaches encounter substantial challenges and environmental impacts, making them unsuitable for sustainable, long-term use. A comparison of the costs of MLD systems with those of brine disposal methods, excluding potential income from the sale of recovered water or solid salt, is essential. As illustrated in Figure 7, the financial outlay for MLD systems exceeds that of lower-cost disposal options, such as discharge into surface water or sewer systems. However, the expenses of MLD systems are comparable to those of land application and deep-well injection, which is expected due to the greater complexity of these disposal methods relative to surface water or sewer discharge. Importantly, MLD systems are considerably more economical than evaporation ponds, with costs at least 3.3 times lower. To further elucidate the economic aspects, Figure 8 presents a profit and loss analysis of brine disposal methods and MLD systems. As shown in Figure 8, traditional disposal methods only incur costs, as they do not produce marketable water. In contrast, MLD systems generate revenue, with the highest profitability observed in the island of Cyprus.

3.4. Present Developments and Future Outlook

While MLD systems aim to maximize water production and reduce waste generation, their deployment may result in unintended environmental consequences. These systems often prioritize the management of liquid waste during the treatment process, leading to the creation of concentrated multi-component streams that require disposal in evaporation ponds. However, such disposal methods pose risks of leakage and generate odors that can harm ecosystems. To mitigate these risks, impermeable liners and monitoring systems are essential to prevent environmental contamination. In recent years, the concept of brine mining has emerged as a complementary approach to water recovery, focusing on extracting valuable resources from waste streams. Although discharge remains a necessity in MLD systems, industries can utilize high-purity concentrated streams internally, thereby reducing raw material costs. By designing MLD systems to recover reusable raw materials, industries can adopt a circular economy approach.
Although MLD systems, which rely on membrane-based technologies, consume significantly less energy than ZLD systems that combine thermal and membrane processes, their energy requirements still contribute to substantial greenhouse gas (GHG) emissions and air pollutants. To address this issue, the integration of renewable energy sources (RESs), such as solar, wind, and geothermal energy, or the utilization of industrial waste heat, is recommended. For instance, solar-powered RO systems emit only 0.2 kg of CO2 per cubic meter of water, which is nine times lower than the emissions from conventional fossil-fuel-powered RO systems (1.8 kg of CO2 per cubic meter). Consequently, combining MLD systems with RESs is seen as a viable strategy to reduce GHG emissions [65,68,69].
To further enhance the efficiency of MLD systems, advancements in the technologies employed are necessary. Energy consumption in the MLD systems can be minimized through strategic integration of energy recovery devices (ERDs) in the HPRO stage, optimizing operating pressures, and utilizing waste heat for the MD unit. Additionally, coupling RESs, such as solar thermal for MD, can further reduce reliance on grid electricity [59]. In particular, adding an ERD directly lowers the HPRO unit’s estimated net specific energy consumption, and integrating solar thermal energy for the MD process lowers electricity-related operating costs, both of which significantly improve the assessment’s overall economic viability and sustainability. Recent developments in membrane technology, such as omniphobic, Janus, and superhydrophobic membranes, have demonstrated significant potential to improve MD performance [47,51,70,71,72,73,74]. Additionally, innovations in membranes and modules are anticipated to increase the upper limit operating pressure in HPRO systems in the near future.
Concentrated brine streams from the MLD system can be valorized through salt extraction (e.g., NaCl for road de-icing) or mineral recovery (e.g., magnesium hydroxide). Emerging strategies include integrating ED or FO to extract valuable ions (e.g., lithium, cesium), aligning with circular economy principles [75,76,77,78,79]. The proposed MLD system is adaptable for industrial effluents, provided that pretreatment removes non-ionic contaminants (e.g., heavy metals, oils) [80,81,82,83,84,85]. Future work will explore scaling the system for textile and pharmaceutical wastewater treatment. This methodology for techno-economic assessment is inherently flexible. The system could be extended to incorporate different pretreatment options to handle specific contaminants found in complex industrial effluents [86]. For example, this could involve integrating advanced oxidation processes (AOPs) for the degradation of non-ionic, refractory organic compounds or nanofiltration (NF) for the targeted removal of divalent ions and certain micropollutants prior to the MLD system. In overall, the specific energy consumption (23.2 kWh/m3) and operational cost (USD 0.99/m3) of the proposed HPRO-MD MLD system align with values reported for comparable MLD/ZLD configurations in the literature (e.g., 15–30 kWh/m3 and USD 0.80–USD 1.50/m3) [53,66]. However, these metrics are highly sensitive to site-specific parameters, such as plant capacity, feed salinity, energy tariffs, and regulatory requirements, underscoring the need for context-driven assessments.

4. Conclusions

This study conducted a TEA of a MLD membrane-based system integrating HPRO and MD for desalination brine treatment. The results demonstrate that the hybrid HPRO-MD system achieves a high water recovery rate of 78.65%, with 39.65 m3/day recovered from MD and 39 m3/day from HPRO.
The total energy consumption of the system is 23.2 kWh/m3, with MD accounting for 89% of the energy demand and HPRO contributing only 11%. The cost analysis reveals an operational cost of USD 0.99/m3, with MD representing 60% of total expenses and HPRO representing 40%. Economic feasibility varies by region, with the system generating a net revenue of USD 228/day in Cyprus and USD 157/day in Greece. Compared to conventional brine disposal, MLD is 3.3 times cheaper than evaporation ponds and offers cost parity with land application and deep-well injection.
While the system offers a sustainable solution for brine management, challenges remain regarding energy consumption and concentrated waste disposal. Future research should explore the integration of RESs to reduce GHG emissions, advancements in membrane materials (e.g., omniphobic, Janus, and superhydrophobic membranes), and opportunities for resource recovery via brine mining. The system exhibits great potential for adaptation to other challenging water streams in terms of future applications. Its use in industrial effluents that contain organic dyes or heavy metals, for example, might be investigated. This would probably require the integration of particular pretreatment processes, like advanced oxidation or ion exchange, before the HPRO unit. The impact of this MLD approach could be increased if future modeling and experimental research confirm the techno-economic viability of these enlarged applications. Overall, the HPRO-MD MLD system provides an energy-efficient, cost-effective, and environmentally sustainable approach to brine treatment, supporting circular economy principles and water resource sustainability.

Supplementary Materials

The following supporting information can be downloaded at: https://www.mdpi.com/article/10.3390/separations12090224/s1, Table S1: The formulas utilized in the techno-economic assessment (TEA) carried out in this study; Figure S1: A visual representation (including flows) showing the configuration of the MLD system, particularly the HPRO-MD process.

Funding

This research received no external funding.

Data Availability Statement

The original contributions presented in this study are included in the article/Supplementary Material. Further inquiries can be directed to the corresponding author.

Conflicts of Interest

The author declares no conflict of interest.

References

  1. Elewa, M.M. Emerging and Conventional Water Desalination Technologies Powered by Renewable Energy and Energy Storage Systems toward Zero Liquid Discharge. Separations 2024, 11, 291. [Google Scholar] [CrossRef]
  2. Liu, J.; Sun, Y.; Zhang, Y.; Wang, J. Theoretical Study of a Closed-Cycle Evaporation System for Seawater Desalination. Separations 2023, 10, 319. [Google Scholar] [CrossRef]
  3. Yang, Q.; Heng, Y.; Jiang, Y.; Luo, J. Multiscale Analysis of Permeable and Impermeable Wall Models for Seawater Reverse Osmosis Desalination. Separations 2023, 10, 134. [Google Scholar] [CrossRef]
  4. Poirier, K.; Al Mhanna, N.; Patchigolla, K. Techno-Economic Analysis of Brine Treatment by Multi-Crystallization Separation Process for Zero Liquid Discharge. Separations 2022, 9, 295. [Google Scholar] [CrossRef]
  5. Castillo-Téllez, B.; Romero, R.J.; Allaf, K.; Pilatowsky-Figueroa, I. Saline Diffusion Modeling for Sodium Chloride Aqueous Solutions: Freezing for Desalination Purposes. Separations 2022, 9, 272. [Google Scholar] [CrossRef]
  6. Huang, L.; Wang, D.; He, C.; Pan, M.; Zhang, B.; Chen, Q.; Ren, J. Industrial Wastewater Desalination under Uncertainty in Coal-Chemical Eco-Industrial Parks. Resour. Conserv. Recycl. 2019, 145, 370–378. [Google Scholar] [CrossRef]
  7. Das, T.K. Industrial Environmental Management; John Wiley & Sons: Hoboken, NJ, USA, 2020. [Google Scholar]
  8. Bonnail, E.; Vera, S.; DelValls, T.Á. A New Disruptive Technology for Zero-Brine Discharge: Towards a Paradigm Shift. Appl. Sci. 2023, 13, 13092. [Google Scholar] [CrossRef]
  9. Wang, T.; Liang, H.; Bai, L.; Liu, B.; Zhu, X.; Wang, J.; Xing, J.; Ren, N.; Li, G. Desalination Performance and Fouling Mechanism of Capacitive Deionization: Effects of Natural Organic Matter. J. Electrochem. Soc. 2020, 167, 043501. [Google Scholar] [CrossRef]
  10. Panagopoulos, A.; Haralambous, K.-J. Minimal Liquid Discharge (MLD) and Zero Liquid Discharge (ZLD) Strategies for Wastewater Management and Resource Recovery—Analysis, Challenges and Prospects. J. Environ. Chem. Eng. 2020, 8, 104418. [Google Scholar] [CrossRef]
  11. Panagopoulos, A.; Giannika, V. Decarbonized and Circular Brine Management/Valorization for Water & Valuable Resource Recovery via Minimal/Zero Liquid Discharge (MLD/ZLD) Strategies. J. Environ. Manage 2022, 324, 116239. [Google Scholar] [CrossRef]
  12. Cifuentes-Cabezas, M.; García-Suarez, L.; Soler-Cabezas, J.L.; Cuartas-Uribe, B.; Álvarez-Blanco, S.; Mendoza-Roca, J.A.; Vincent-Vela, M.C. Feasibility of Forward Osmosis to Recover Textile Dyes Using Single Salts and Multicomponent Draw Solutions. Membranes 2023, 13, 911. [Google Scholar] [CrossRef] [PubMed]
  13. Altınay, A.D.; Yazagan, A.; Koseoglu-Imer, D.Y.; Keskinler, B.; Koyuncu, I. Membrane Concentrate Management Model of Biologically Pre-Treated Textile Wastewater for Zero-Liquid Discharge. Water Air Soil. Pollut. 2022, 233, 303. [Google Scholar] [CrossRef]
  14. Natarajan, P.; Karmegam, P.M.; Madasamy, J.; Somasundaram, S.; Ganesan, S. Effective Treatment of Domestic Sewage to Reuse in Textile Dyeing and Catalytic Treatment of Generated Dye Wastewater. Int. J. Environ. Sci. Technol. 2022, 20, 6209–6220. [Google Scholar] [CrossRef]
  15. Zakari-Jiya, A.; Frazzoli, C.; Obasi, C.N.; Babatunde, B.B.; Patrick-Iwuanyanwu, K.C.; Orisakwe, O.E. Pharmaceutical and Personal Care Products as Emerging Environmental Contaminants in Nigeria: A Systematic Review. Environ. Toxicol. Pharmacol. 2022, 94, 103914. [Google Scholar] [CrossRef] [PubMed]
  16. Vaudreuil, M.A.; Vo Duy, S.; Munoz, G.; Sauvé, S. Pharmaceutical Pollution of Hospital Effluents and Municipal Wastewaters of Eastern Canada. Sci. Total Environ. 2022, 846, 157353. [Google Scholar] [CrossRef]
  17. Ghurye, G.L. Evaluation of a Minimum Liquid Discharge (Mld) Desalination Approach for Management of Unconventional Oil and Gas Produced Waters with a Focus on Waste Minimization. Water 2021, 13, 2912. [Google Scholar] [CrossRef]
  18. Panagopoulos, A. Brine Management (Saline Water & Wastewater Effluents): Sustainable Utilization and Resource Recovery Strategy through Minimal and Zero Liquid Discharge (MLD & ZLD) Desalination Systems. Chem. Eng. Process. Process Intensif. 2022, 176, 108944. [Google Scholar] [CrossRef]
  19. Rotko, G.; Knapik, E.; Piotrowski, M.; Marszałek, M. Oilfield Brine as a Source of Water and Valuable Raw Materials—Proof of Concept on a Laboratory Scale. Water 2024, 16, 1461. [Google Scholar] [CrossRef]
  20. Zhang, H.; Xing, J.; Wei, G.; Wang, X.; Chen, S.; Quan, X. Electrostatic-Induced Ion-Confined Partitioning in Graphene Nanolaminate Membrane for Breaking Anion–Cation Co-Transport to Enhance Desalination. Nat. Commun. 2024, 15, 4324. [Google Scholar] [CrossRef]
  21. Kress, N. Marine Impacts of Seawater Desalination: Science, Management, and Policy; Elsevier: Amsterdam, The Netherlands, 2019; ISBN 9780128119532. [Google Scholar]
  22. Kress, N.; Gertner, Y.; Shoham-Frider, E. Seawater Quality at the Brine Discharge Site from Two Mega Size Seawater Reverse Osmosis Desalination Plants in Israel (Eastern Mediterranean). Water Res. 2020, 171, 115402. [Google Scholar] [CrossRef] [PubMed]
  23. Theodore, L.; Dupont, R.R. Introduction to Desalination: Principles and Calculations, 1st ed.; John Wiley & Sons: Hoboken, NJ, USA, 2021; ISBN 9781119691754. [Google Scholar]
  24. DuPont. DUPONTTM XUS180808 Reverse Osmosis Element Product Data Sheet; DuPont: Wilmington, DE, USA, 2023. [Google Scholar]
  25. Dow Water Solutions. Dows Minimal Liquid Discharge Approach Takes Center Stage; Dow Water Solutions: Wilmington, DE, USA, 2023. [Google Scholar]
  26. Panagopoulos, A. Techno-Economic Assessment of Minimal Liquid Discharge (MLD) Treatment Systems for Saline Wastewater (Brine) Management and Treatment. Process Saf. Environ. Prot. 2021, 146, 656–669. [Google Scholar] [CrossRef]
  27. Veolia Water Technologies Brine Concentrator System: HPD®Evaporation and Crystallization. 2023. Available online: https://www.veoliawatertech.com/en/solutions/technologies/hpd-evaporation-crystallization (accessed on 1 June 2025).
  28. Yang, M.; Chen, L.; Wang, J.; Msigwa, G.; Osman, A.I.; Fawzy, S.; Rooney, D.W.; Yap, P.S. Circular Economy Strategies for Combating Climate Change and Other Environmental Issues. Environ. Chem. Lett. 2023, 21, 55–80. [Google Scholar] [CrossRef]
  29. Ossio, F.; Salinas, C.; Hernández, H. Circular Economy in the Built Environment: A Systematic Literature Review and Definition of the Circular Construction Concept. J. Clean. Prod. 2023, 414, 137738. [Google Scholar] [CrossRef]
  30. Zaman, A.; Caceres Ruiz, A.M.; Shooshtarian, S.; Ryley, T.; Caldera, S.; Maqsood, T. Development of the Circular Economy Design Guidelines for the Australian Built Environment Sector. Sustainability 2023, 15, 2500. [Google Scholar] [CrossRef]
  31. Arora, R.; Mutz, D.; Mohanraj, P. Innovating for the Circular Economy, 1st ed.; CRC Press: Boca Raton, FL, USA, 2023; p. 147. ISBN 9781032063386. [Google Scholar]
  32. Nestorovic, M.; Radicevic, T.D.; Belgrade, F.; Sad, N. Transition to Circular Economy. In Proceedings of the 41st International Scientific Conference on Economic and Social Development, Belgrade, Serbia, 23–24 May 2019. [Google Scholar]
  33. Morseletto, P. Targets for a Circular Economy. Resour. Conserv. Recycl. 2020, 153, 104553. [Google Scholar] [CrossRef]
  34. Saltworks Technologies Inc. Zero Liquid Discharge and Minimal Liquid Discharge; Saltworks Technologies Inc.: Richmond, BC, Canada, 2022. [Google Scholar]
  35. Panagopoulos, A. Techno-Economic Assessment of Zero Liquid Discharge (ZLD) Systems for Sustainable Treatment, Minimization and Valorization of Seawater Brine. J. Environ. Manag. 2022, 306, 114488. [Google Scholar] [CrossRef]
  36. Criscuoli, A. The Potential of Membrane Contactors in the Pre-Treatment and Post-Treatment Lines of a Reverse Osmosis Desalination Plant. Separations 2023, 10, 129. [Google Scholar] [CrossRef]
  37. Lin, S. Energy Efficiency of Desalination: Fundamental Insights from Intuitive Interpretation. Environ. Sci. Technol. 2020, 54, 76–84. [Google Scholar] [CrossRef] [PubMed]
  38. Bazargan, A. A Multidisciplinary Introduction to Desalination; River Publishers: Gistrup, Denmark, 2018; ISBN 9788793379534. [Google Scholar]
  39. Rosen, M.; Farsi, A. Sustainable Energy Technologies for Seawater Desalination; Academic Press: Cambridge, MA, USA, 2022; ISBN 9780323998727. [Google Scholar]
  40. Mujtaba, I.M.; Sowgath, M.T. Desalination Technologies: Design and Operation; Elsevier: Amsterdam, The Netherlands, 2022. [Google Scholar]
  41. Chen, Q.; Luo, J.; Heng, Y. High-Throughput Optimal Design of Spacers Using Triply Periodic Minimal Surfaces in BWRO. Separations 2022, 9, 62. [Google Scholar] [CrossRef]
  42. Lim, Y.J.; Nadzri, N.; Xue, Q.; Li, C.; Wang, R. Investigating the Impact of TFC Membrane Structure and Compaction on Performance in Hypersaline Brine Desalination via High-Pressure Reverse Osmosis. Desalination 2025, 607, 118793. [Google Scholar] [CrossRef]
  43. Lim, Y.J.; Goh, K.; Nadzri, N.; Wang, R. Thin-Film Composite (TFC) Membranes for Sustainable Desalination and Water Reuse: A Perspective. Desalination 2025, 599, 118451. [Google Scholar] [CrossRef]
  44. Lim, Y.J.; Nadzri, N.; Lai, G.S.; Wang, R. Demystifying the Compaction Effects of TFC Polyamide Membranes in the Desalination of Hypersaline Brine via High-Pressure RO. J. Memb. Sci. 2024, 707, 122950. [Google Scholar] [CrossRef]
  45. Lim, Y.J.; Ma, Y.; Chew, J.W.; Wang, R. Assessing the Potential of Highly Permeable Reverse Osmosis Membranes for Desalination: Specific Energy and Footprint Analysis. Desalination 2022, 533, 115771. [Google Scholar] [CrossRef]
  46. Choi, Y.; Ryu, S.; Naidu, G.; Lee, S.; Vigneswaran, S. Integrated Submerged Membrane Distillation-Adsorption System for Rubidium Recovery. Sep. Purif. Technol. 2019, 218, 146–155. [Google Scholar] [CrossRef]
  47. Ni, T.; Lin, J.; Kong, L.; Zhao, S. Omniphobic Membranes for Distillation: Opportunities and Challenges. Chin. Chem. Lett. 2021, 32, 3298–3306. [Google Scholar] [CrossRef]
  48. Prasanna, N.S.; Choudhary, N.; Singh, N.; Raghavarao, K.S.M.S. Omniphobic Membranes in Membrane Distillation for Desalination Applications: A Mini-Review. Chem. Eng. J. Adv. 2023, 14, 100486. [Google Scholar] [CrossRef]
  49. Tan, Y.Z.; Alias, N.H.; Aziz, M.H.A.; Jaafar, J.; Othman, F.E.C.; Chew, J.W. Progress on Improved Fouling Resistance-Nanofibrous Membrane for Membrane Distillation: A Mini-Review. Membranes 2023, 13, 727. [Google Scholar] [CrossRef]
  50. Panagopoulos, A. Process Simulation and Analysis of High-Pressure Reverse Osmosis (HPRO) in the Treatment and Utilization of Desalination Brine (Saline Wastewater). Int. J. Energy Res. 2022, 46, 23083–23094. [Google Scholar] [CrossRef]
  51. Chen, L.H.; Huang, A.; Chen, Y.R.; Chen, C.H.; Hsu, C.C.; Tsai, F.Y.; Tung, K.L. Omniphobic Membranes for Direct Contact Membrane Distillation: Effective Deposition of Zinc Oxide Nanoparticles. Desalination 2018, 428, 255–263. [Google Scholar] [CrossRef]
  52. Panagopoulos, A. Study and Evaluation of the Characteristics of Saline Wastewater (Brine) Produced by Desalination and Industrial Plants. Environ. Sci. Pollut. Res. 2022, 29, 23736–23749. [Google Scholar] [CrossRef]
  53. Panagopoulos, A. Energetic, Economic and Environmental Assessment of Zero Liquid Discharge (ZLD) Brackish Water and Seawater Desalination Systems. Energy Convers. Manag. 2021, 235, 113957. [Google Scholar] [CrossRef]
  54. DuPont. FILMTECTM Reverse Osmosis Membranes: Technical Manual. 2024. Available online: https://www.dupont.com/content/dam/water/amer/us/en/water/public/documents/en/RO-NF-FilmTec-Manual-45-D01504-en.pdf (accessed on 1 June 2025).
  55. EDEYA. Water Prices; EDEYA: Athens, Greece, 2023. [Google Scholar]
  56. Nowtricity Electricity CO2 Emissions per KWh in Greece. Current Production by Electricity Source and Average Emissions by Month and Year. 2025. Available online: https://www.nowtricity.com/country/greece/ (accessed on 1 June 2025).
  57. Moradi, M.R.; Pihlajamäki, A.; Hesampour, M.; Ahlgren, J.; Mänttäri, M. End-of-Life RO Membranes Recycling: Reuse as NF Membranes by Polyelectrolyte Layer-by-Layer Deposition. J. Memb. Sci. 2019, 584, 300–308. [Google Scholar] [CrossRef]
  58. Gaid, K. Drinking Water Treatment: Membranes Applied to Drinking Water and Desalination; John Wiley & Sons: Hoboken, NJ, USA, 2023; Volume 4, ISBN 9781394226122. [Google Scholar]
  59. Ismail, A.F.; Khulbe, K.C.; Matsuura, T. Reverse Osmosis; Elsevier: Amsterdam, The Netherlands, 2018; ISBN 9780128114681. [Google Scholar]
  60. Ghangrekar, M.M. Wastewater to Water: Principles, Technologies and Engineering Design; Springer: Berlin/Heidelberg, Germany, 2023; ISBN 9789811940477/9789811940484. [Google Scholar]
  61. Nasr, M.; Negm, A.M. Cost-Efficient Wastewater Treatment Technologies. Eng. Syst. 2023, 118, 1–184. [Google Scholar]
  62. Shah, M.P. Membrane and Membrane-Based Processes for Wastewater Treatment; CRC Press: Boca Raton, FL, USA, 2023. [Google Scholar]
  63. Droste, R.L.; Gehr, R.L. Theory and Practice of Water and Wastewater Treatment; John Wiley & Sons: Hoboken, NJ, USA, 2018. [Google Scholar]
  64. Panagopoulos, A. Assessing the Energy Footprint of Desalination Technologies and Minimal/Zero Liquid Discharge (MLD/ZLD) Systems for Sustainable Water Protection via Renewable Energy Integration. Energies 2025, 18, 962. [Google Scholar] [CrossRef]
  65. Panagopoulos, A.; Michailidis, P. Membrane Technologies for Sustainable Wastewater Treatment: Advances, Challenges, and Applications in Zero Liquid Discharge (ZLD) and Minimal Liquid Discharge (MLD) Systems. Membranes 2025, 15, 64. [Google Scholar] [CrossRef]
  66. Panagopoulos, A. Resource Recovery Via Minimal Liquid Discharge (MLD) and Zero Liquid Discharge (ZLD): A Biotechnological Approach. In Smart Waste and Wastewater Management by Biotechnological Approaches; Mohd, Y.A., Sillanpää, M., Eds.; Springer Nature: Singapore, 2025; pp. 379–392. ISBN 978-981-97-8673-2. [Google Scholar]
  67. Panagopoulos, A. Zero Liquid Discharge (ZLD) and Minimal Liquid Discharge (MLD) Technologies for Sustainable Wastewater Management and Valorization. In Smart Waste and Wastewater Management by Biotechnological Approaches; Mohd, Y.A., Sillanpää, M., Eds.; Springer Nature: Singapore, 2025; pp. 307–320. ISBN 978-981-97-8673-2. [Google Scholar]
  68. Gude, V.G. Renewable Energy Powered Desalination Handbook: Application and Thermodynamics; Butterworth-Heinemann: Oxford, UK, 2018; ISBN 9780128152447. [Google Scholar]
  69. Gude, V.G. Sustainable Desalination Handbook: Plant Selection, Design and Implementation; Butterworth-Heinemann: Oxford, UK, 2018; ISBN 9780128094969. [Google Scholar]
  70. Dong, Y.; Ma, L.; Tang, C.Y.; Yang, F.; Quan, X.; Jassby, D.; Zaworotko, M.J.; Guiver, M.D. Stable Superhydrophobic Ceramic-Based Carbon Nanotube Composite Desalination Membranes. Nano Lett. 2018, 18, 5514–5521. [Google Scholar] [CrossRef]
  71. Su, Q.; Zhang, J.; Zhang, L.Z. Fouling Resistance Improvement with a New Superhydrophobic Electrospun PVDF Membrane for Seawater Desalination. Desalination 2020, 476, 114246. [Google Scholar] [CrossRef]
  72. Naseem, S.; Wu, C.M.; Motora, K.G. Novel Multifunctional RbxWO3@Fe3O4 Immobilized Janus Membranes for Desalination and Synergic-Photocatalytic Water Purification. Desalination 2021, 517, 115256. [Google Scholar] [CrossRef]
  73. Namdari, M.; Zokaee Ashtiani, F.; Bonyadi, E. Development of a High Flux Janus PVDF Membrane for Oily Saline Water Desalination by Membrane Distillation via PDA-TEOS-APTES Surface Modification. Desalination 2024, 572, 117139. [Google Scholar] [CrossRef]
  74. Zhang, W.; Yu, S.; Li, P.; Ji, X.; Ning, R.; Li, P. Preparation Janus Membrane via Polytetrafluoroethylene Membrane Modification for Enhanced Performance of Vacuum Membrane Distillation Desalination. Sep. Purif. Technol. 2023, 313, 123465. [Google Scholar] [CrossRef]
  75. Li, Z.; Binnemans, K. Selective Removal of Magnesium from Lithium-Rich Brine for Lithium Purification by Synergic Solvent Extraction Using β-Diketones and Cyanex 923. AIChE J. 2020, 66, e16246. [Google Scholar] [CrossRef]
  76. Li, X.; Mo, Y.; Qing, W.; Shao, S.; Tang, C.Y.; Li, J. Membrane-Based Technologies for Lithium Recovery from Water Lithium Resources: A Review. J. Memb. Sci. 2019, 591, 117317. [Google Scholar] [CrossRef]
  77. Alsabbagh, A.; Aljarrah, S.; Almahasneh, M. Lithium Enrichment Optimization from Dead Sea End Brine by Chemical Precipitation Technique. Miner. Eng. 2021, 170, 107038. [Google Scholar] [CrossRef]
  78. Liu, G.; Zhao, Z.; Ghahreman, A. Novel Approaches for Lithium Extraction from Salt-Lake Brines: A Review. Hydrometallurgy 2019, 187, 81–100. [Google Scholar] [CrossRef]
  79. Chen, W.S.; Lee, C.H.; Chung, Y.F.; Tien, K.W.; Chen, Y.J.; Chen, Y.A. Recovery of Rubidium and Cesium Resources from Brine of Desalination through T-BAMBP Extraction. Metals 2020, 10, 607. [Google Scholar] [CrossRef]
  80. Abdullah, N.; Tajuddin, M.H.; Yusof, N. 10-Forward Osmosis (FO) for Removal of Heavy Metals; Elsevier: Amsterdam, The Netherlands, 2018; ISBN 9780128139035. [Google Scholar]
  81. Imdad, S.; Dohare, R.K. A Critical Review On Heavy Metals Removal Using Ionic Liquid Membranes From The Industrial Wastewater. Chem. Eng. Process. Process Intensif. 2022, 173, 108812. [Google Scholar] [CrossRef]
  82. Carmona, B.; Abejón, R. Innovative Membrane Technologies for the Treatment of Wastewater Polluted with Heavy Metals: Perspective of the Potential of Electrodialysis, Membrane Distillation, and Forward Osmosis from a Bibliometric Analysis. Membranes 2023, 13, 385. [Google Scholar] [CrossRef] [PubMed]
  83. Nozaki, K.; Tanoue, R.; Kunisue, T.; Tue, N.M.; Fujii, S.; Sudo, N.; Isobe, T.; Nakayama, K.; Sudaryanto, A.; Subramanian, A.; et al. Pharmaceuticals and Personal Care Products (PPCPs) in Surface Water and Fish from Three Asian Countries: Species-Specific Bioaccumulation and Potential Ecological Risks. Sci. Total Environ. 2023, 866, 161258. [Google Scholar] [CrossRef] [PubMed]
  84. Zhou, T.; Zhang, Z.; Liu, H.; Dong, S.; Nghiem, L.D.; Gao, L.; Chaves, A.V.; Zamyadi, A.; Li, X.; Wang, Q. A Review on Microalgae-Mediated Biotechnology for Removing Pharmaceutical Contaminants in Aqueous Environments: Occurrence, Fate, and Removal Mechanism. J. Hazard. Mater. 2023, 443, 130213. [Google Scholar] [CrossRef]
  85. Wilkinson, J.L.; Hooda, P.S.; Barker, J.; Barton, S.; Swinden, J. Ecotoxic Pharmaceuticals, Personal Care Products, and Other Emerging Contaminants: A Review of Environmental, Receptor-Mediated, Developmental, and Epigenetic Toxicity with Discussion of Proposed Toxicity to Humans. Crit. Rev. Environ. Sci. Technol. 2016, 46, 336–381. [Google Scholar] [CrossRef]
  86. Panagopoulos, A. Beneficiation of Saline Effluents from Seawater Desalination Plants: Fostering the Zero Liquid Discharge (ZLD) Approach—A Techno-Economic Evaluation. J. Environ. Chem. Eng. 2021, 9, 105338. [Google Scholar] [CrossRef]
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Figure 1. A visual representation showing the configuration of the MLD system, particularly the HPRO-MD process.
Figure 1. A visual representation showing the configuration of the MLD system, particularly the HPRO-MD process.
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Figure 2. The impact of HPRO and MD processes on water recovery, declared as a percentage.
Figure 2. The impact of HPRO and MD processes on water recovery, declared as a percentage.
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Figure 3. The impact of HPRO and MD processes on energy demands, declared as a percentage.
Figure 3. The impact of HPRO and MD processes on energy demands, declared as a percentage.
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Figure 4. The impact of HPRO and MD processes on cost demands, declared as a percentage.
Figure 4. The impact of HPRO and MD processes on cost demands, declared as a percentage.
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Figure 5. The profitability of the MLD system utilizing HPRO and MD processes in Greece and Cyprus.
Figure 5. The profitability of the MLD system utilizing HPRO and MD processes in Greece and Cyprus.
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Figure 6. Cost comparison between the MLD system and conventional drinking water sources.
Figure 6. Cost comparison between the MLD system and conventional drinking water sources.
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Figure 7. Cost comparison of the MLD system versus disposal methods, excluding profit considerations.
Figure 7. Cost comparison of the MLD system versus disposal methods, excluding profit considerations.
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Figure 8. Value assessment of the MLD system compared to disposal methods, including profit considerations.
Figure 8. Value assessment of the MLD system compared to disposal methods, including profit considerations.
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Table 2. The information and assumptions applied in the techno-economic assessment (TEA) conducted in this study.
Table 2. The information and assumptions applied in the techno-economic assessment (TEA) conducted in this study.
ItemValueReferences
Projected operational duration of the facility30 yearsassumption
Interest rate imposed5%assumption
Charge for water in CyprusUSD 3.9 per cubic meter[53]
Storage unit for the feed solutionUSD 93.6 per cubic meter[53]
Storage tank for freshwaterUSD 75.53 per cubic meter[53]
Rate of flow for the feed solution100 cubic meters per dayassumption
Level of salinity in the feed solution38 g per liter[53]
Chemical consumption expensesUSD 0.0176 per cubic meter[53]
Utility service chargesUSD 41.04 per cubic meter per day[53]
Monetary outlay for pretreatment processesUSD 79.26 per cubic meter per day[53]
Expenditure for maintenance and replacement partsUSD 0.019 per cubic meter[53]
Cost of electricity usageUSD 0.064 per kilowatt-hour[53]
Workforce-related expendituresUSD 0.0315 per cubic meter[53]
Land development and site preparation expensesUSD 25.33 per cubic meter per day[53]
Cost for miscellaneous expendituresUSD 83.2 per cubic meter per day[53]
Determining factor for plant availability90%assumption
Cost of water in GreeceUSD 3 per cubic meter[55]
Feed solution compositionCa2+ (417 mg/L), Mg2+ (1401 mg/L), Cl− (22,661 mg/L), Na+ (11,853 mg/L), K+ (454 mg/L), SO42− (1182 mg/L), and HCO3− (46 mg/L)[53]
Membrane materialHPRO: thin-film composite (TFC) membrane with a polyamide layer; MD: hydrophobic polyvinylidene fluoride (PVDF) membrane[24,54]
Grid emission factor for the Eastern Mediterranean region (Greece)0.256 kg CO2-eq/kWh[56]
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Panagopoulos, A. Techno-Economic Assessment (TEA) of a Minimal Liquid Discharge (MLD) Membrane-Based System for the Treatment of Desalination Brine. Separations 2025, 12, 224. https://doi.org/10.3390/separations12090224

AMA Style

Panagopoulos A. Techno-Economic Assessment (TEA) of a Minimal Liquid Discharge (MLD) Membrane-Based System for the Treatment of Desalination Brine. Separations. 2025; 12(9):224. https://doi.org/10.3390/separations12090224

Chicago/Turabian Style

Panagopoulos, Argyris. 2025. "Techno-Economic Assessment (TEA) of a Minimal Liquid Discharge (MLD) Membrane-Based System for the Treatment of Desalination Brine" Separations 12, no. 9: 224. https://doi.org/10.3390/separations12090224

APA Style

Panagopoulos, A. (2025). Techno-Economic Assessment (TEA) of a Minimal Liquid Discharge (MLD) Membrane-Based System for the Treatment of Desalination Brine. Separations, 12(9), 224. https://doi.org/10.3390/separations12090224

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