Integrating Circular Economy Principles in Petroleum Produced Water Management: Toward Sustainable Resource Recovery and Waste Minimization

Abstract

Oil production generates approximately 250 million barrels of produced water (PW) daily, nearly three times the volume of oil, with salinity levels reaching up to 300,000 ppm. Improper management of this wastewater causes significant environmental degradation, including soil salinization and aquatic toxicity. To address these impacts, this study applies circular economy (CE) principles to PW management through flash vaporization and resource recovery. Implementing this approach enables 85–90% water recovery and reduces salinity to below 1000 ppm, allowing reuse for irrigation. Simultaneously, residual brine processed via evaporation ponds yields 15–25% potash (KCl) and 30–40% halite (NaCl), thereby transforming waste into valuable products. As a result, the integrated CE process can reduce wastewater disposal by 80%, cut greenhouse gas emissions by 25–30%, and lower treatment costs by 20–35%, while generating additional revenue of $150–300 per ton of recovered potash. These outcomes demonstrate that adopting CE strategies in PW management not only mitigates environmental degradation but also strengthens economic resilience and resource efficiency. The framework offers a scalable pathway for achieving the UN Sustainable Development Goals (SDG 6 and 12) and advancing sustainability within the oil and gas industry.

1. Introduction

The search and extraction of oil have been essential to human civilization across history for energy needs. Despite the worldwide transition to renewable energy, fossil fuels still dominate, as coal and natural gas account for 35.5% and 23%, respectively, of the global power mix in 2023 [1]. Nonetheless, oil extraction poses considerable environmental challenges, especially in relation to the handling of produced water (PW), a by-product that has salinity levels over 300,000 ppm [2,3]. This extremely salty formation water presents significant challenges for environmental and resource management, as its direct release into oceans is harmful because of its chemical composition [2,4]. In 2020, the projected volume of PW production was around 250 million barrels per day [5,6]. Addressing this volume demands innovative approaches, including the implementation of a circular economy (CE) model.

CE principles focus on reducing waste, improving resource efficiency, and lessening environmental impact [7,8,9,10,11]. Many oil and gas companies have already implemented several guidelines for CE in their operations to reduce emissions and recycle several byproducts including salts, hydrogen sulfide, and formation water [8,9,10]. The utilization of artificial intelligence and digitization have also played an integral role in this initiative through optimization of available resources [8,9,10,11]. Additionally, in the petroleum industry, CE tactics can convert formation water into valuable resources such as irrigation water or potash, an essential fertilizer ingredient [2,12,13,14,15,16]. New methods, such as thermal evaporation, desalination via membranes, and oxidation, have shown efficacy in processing PW to comply with standards for agricultural or potable water [2,3,17]. Moreover, the brine by-product generated from PW treatment can function as a raw material for potash, tackling challenges in both agricultural and industrial productivity [12]. Sustainable tannery wastewater management requires a multi-stage, integrated treatment approach and greater emphasis on reuse and resource recovery. Hybrid technologies that combine AOPs, biological processes, and membrane systems are the most effective solutions for minimizing environmental damage and promoting circularity in the leather industry [18].

These actions help in attaining the United Nations Sustainable Development Goals (SDGs), particularly SDG 6 (Clean Water and Sanitation) and SDG 12 (Responsible Consumption and Production) [19]. Applying CE principles provides environmental advantages that extend beyond resource recovery, including minimizing ecosystem harm and improving biodiversity conservation [3].

As discussed above, prior studies have mainly focused on either PW treatment technologies [3,20,21,22,23] or circular economy principles in industrial settings [7,8,9,10,11]. On the contrary, this paper provides the first systematic integration of CE frameworks with petroleum PW management, offering a practical solution. Its novel contributions include: (i) a comprehensive comparative framework that evaluates treatment technologies based explicitly on resource recovery potential rather than mere discharge compliance; (ii) a detailed correlation between flash vaporization outputs and mineral extraction processes (namely, potash production), demonstrating full material circularity; (iii) an economic synthesis of recovery systems across different operational scales; (iv) an identification of technology combinations tailored to diverse PW compositions and operating conditions. Upon exploring the technical, environmental, and economic factors of integrating CE principles with PW management, this review highlights how sustainable development practices can be effectively implemented within the petroleum industry to enhance resource efficiency on a global scale.

2. Methodology of Circular Economy Within the Petroleum Industry

The circular economy model focuses on minimizing environmental impact by using fewer raw materials, producing less waste, and reducing emissions. Instead of the traditional “take–make–dispose” approach, it promotes consumption, reusing, repairing, recycling, and designing products for longevity [24]. By extending the life of materials and products, the model reduces the need for new resource extraction, lowers landfill use, and cuts greenhouse gas emissions, supporting a more sustainable and resource-efficient economy.

Circular economy in oil production emphasizes the closure of material and energy cycles, managing and repurposing PW to provide environmental and economic advantages. Instead of being discarded, PW is treated to reclaim valuable materials and reduce waste and its environmental impact [25].

The system boundaries for this assessment encompass the full lifecycle of produced-water (PW) management. The upstream operations include PW generation and initial separation processes, while the midstream treatment stage covers flash vaporization, evaporation, and mineral recovery. The downstream use phase focuses on the reuse of treated water and recovered minerals in agriculture and industry. Additionally, external inputs and outputs, such as energy (electricity and solar integration), chemicals, and emissions, are incorporated to capture the system’s total environmental footprint [26,27].

Key assumptions include a PW treatment volume of 1000 m³/day, a flash vaporization recovery rate of 85%, and an energy mix composed of 60% grid electricity and 40% renewable (solar or thermal) sources. The market value of recovered potash is estimated at $200 per ton, and a 6% discount rate is applied for the cost–benefit analysis [28].

The framework for economic and environmental assessment integrates multiple complementary methodologies. Life Cycle Assessment (LCA) quantifies greenhouse gas (GHG) emissions (kg CO₂-eq/m³ water treated), energy intensity (kWh/m³), and resource recovery efficiency (%). Life Cycle Costing (LCC) evaluates capital, operational, and maintenance costs per unit of treated water ($/m³), while Cost–Benefit Analysis (CBA) balances the revenues from mineral recovery and water reuse against total investment. Finally, Sustainability Indexing combines environmental indicators (carbon reduction and water savings) with economic indicators (return on investment and payback period) into a composite score that reflects overall system sustainability [29,30].

As illustrated in Figure 1, this circular economy approach redefines produced water from waste into a valuable recoverable resource, enabling oil producers to achieve up to 30% lower lifecycle costs and 25–40% reductions in environmental impact, thereby fostering a more resilient and sustainable energy sector [31].

2.1. Integration of Circular Economy Principles in Produced Water Management

Produced water (PW), traditionally regarded as a waste by-product of oil and gas extraction, is increasingly being re-evaluated as a valuable resource within the framework of the circular economy (CE). In contrast to conventional treatment paradigms that place PW as waste requiring disposal, this study conceptualizes PW as a potential feedstock for value added products. On this basis, this paper examines novel approaches to integrating CE principles into PW management, mainly with a focus on sustainable water reuse, waste minimization, and resource recovery [32].

One of the key components of this approach is resource recovery, where advanced treatment technologies such as membrane filtration and electrocoagulation are employed to extract valuable compounds, hydrocarbons, salts, and trace metals, from PW. These recovered materials can serve as industrial inputs, particularly in the petrochemical sector, thereby reducing dependency on virgin resources [6].

In parallel, energy recovery methods such as membrane bioreactors and anaerobic digestion are used to degrade organic matter in PW, simultaneously generating biogas that can be harnessed for energy production [33]. This not only addresses waste treatment but also contributes to renewable energy generation.

Moreover, repurposing treated PW for irrigation or industrial processes is gaining traction as a way to alleviate freshwater demand and lower environmental pressures in water-scarce regions [34]. These reuse strategies align closely with CE objectives by extending the lifecycle of water resources as discussed later in this article.

Further innovations include flash vaporization techniques that reduce the salinity of PW. The resulting vapor can be used, after being condensed, in agricultural applications, while the concentrated, rejected, brine is directed to evaporation ponds for salt crystallization. The extracted salts are subsequently processed for fertilizer production, thus closing the loop on material flows [13,14,15,16,35].

2.2. Novel Aspects of the Proposed Circular Economy Framework

The CE framework developed in this study is different in three aspects compared to conventional PW management paradigms:

Complete Material Loop Closure: The integration of multi-stage flash (MSF) vaporization and evaporation-pond crystallization provides zero liquid discharge (ZLD) conditions while simultaneously generating valuable coproducts [3,4,21,35,36,37].

Multi-stage flash (MSF) represents the most common type of thermal desalination technique that has been successfully used to treat high-salinity PW to generate low-TDS distillate that can be reused [21,36]. The brine concentration remaining after vaporization can be directed to evaporation ponds or industrial crystallizers so that solid salts such as halite and potash can be extracted as marketable by-products [13,35,37,38].

Material balance calculations from industrial data and field studies [13,36,38] suggest that for every 100 m³ of high-salinity PW (150,000 ppm TDS) processed: approximately 70–75 m³ can be recovered as desalinated water suitable for irrigation (TDS < 500 ppm), 20–25 m³ concentrates to brine (250,000–350,000 ppm TDS), and 2–4 m³ equivalent of crystallized salts suitable for potash production can be recovered [13,38]. This represents genuine circularity rather than a partial reduction in waste [22].

Technology Integration Matrices: Building on previous work of PW treatment technologies [3,21,22,39], the proposed matrix frameworks allow practitioners to identify the most appropriate treatment configuration based on site-specific parameters in-stead of prescribing specific technologies. The main decision variables are as follows: feed water TDS concentration (determining thermal vs. membrane feasibility) [2,40], the level of hydrocarbon content (dictating pretreatment requirements) [25,41], the level of suspended solids (affecting membrane fouling potential) [42], the target water quality standard (agricultural vs. industrial reuse standards) [21,34], the availability of energy sources (waste heat, solar, grid electricity) [43,44,45], and the land footprint (constraining evaporation pond feasibility) [35,45].

Economic–Environmental Co-optimization: Traditional cost–benefit analyses are too narrow and only focus on the treatment costs versus discharge compliance [46,47]. The proposed framework incorporates multi-criteria assessments that not only include financial efficiency but also environmental resilience, social value and long-term sustainability.

Such an approach takes into account factors like water security value (particularly in arid oil-producing regions like the GCC countries) [4,48,49], the emission reduction credits (by avoiding deep-well injection or ocean disposal) [46,47], and resource independence metrics, reflecting reduced reliance on imported fertilizers [37]. It also recognizes the tangible yet often underrepresented value of social license to operate (community acceptance of cleaner production and water reuse) [39,50].

By aligning economic incentives with ecological integrity, this holistic approach is transforming wastewater management from a regulatory obligation into a strategic opportunity for sustainable growth and regional resilience.

3. Challenges and Strengths in the Treatment of Petroleum Produced Water

Produced water often contains a mixture of hydrocarbons, heavy metals, dissolved salts, and various organic and inorganic pollutants [21]. Effective treatment solutions must address not only the removal of these contaminants but also the large volumes involved, the economic feasibility, and the potential environmental consequences of disposal or reuse [3].

A number of treatment approaches have demonstrated promising outcomes/strengths, particularly in identifying key contaminants and aligning with sustainability goals. One notable strength lies in the clear characterization of PW components. Studies have effectively outlined the ecological risks posed by hydrocarbons, metals, and high salinity levels, highlighting the importance of targeted treatment strategies [22].

3.1. Comparative Evaluation of Treatment Technologies

Various treatment technologies provide innovative pathways for reducing such risks, yet each presents distinct advantages and limitations that must be considered in context. The selection of an appropriate technology depends primarily on the characteristics of the produced water (PW), the scale of operations, the availability of re-sources, and the desired quality of the treated output. A concise comparative synthesis of the principal produced-water treatment technologies is presented in

Table 1. Comparative Performance Evaluation of Produced Water Treatment Technologies.

Technology	Optimal TDS Range (ppm)	Energy Demand	Capital Investment	Water Recovery (%)	Key Advantages	Key Limitations	References
Single-Stage Flash Vaporization (SSF)	>100,000	Very High (thermal; unless coupled to waste heat)	Low	10–20	Simple operation; can utilize waste heat; suitable for extreme salinity	Low recovery; very high energy consumption	[3,4]
Multi-Stage Flash (MSF)	>100,000	High relative to membranes	High	40–50	Proven for high-salinity brines; reliable; compatible with ZLD systems	Complex operation; high capital and maintenance costs	[3,22,36]
Ultrafiltration (UF)	10,000–80,000	Very Low (low-pressure)	Low	85–95	Excellent suspended solids removal; ideal RO pre-treatment	No salt removal; sensitive to oil and grease fouling	[3,21,22]
Reverse Osmosis (RO)	<45,000	Moderate (pressure-driven)	Moderate	50–75	High salt rejection; compact design; widely adopted	Fouling; limited to moderate salinity; pretreatment required	[3,21,22]
Membrane Bioreactor (MBR)	<50,000	Low (biological; aeration energy)	Low	Variable	organics removal; biological polishing; suitable for secondary reuse	Salinity stress on microbes; nutrient supplementation required	[3,21]
Advanced Oxidation Processes (AOPs)	Any (TDS-independent)	Very High (oxidant/UV/ozone energy)	High	90–98	Removes refractory organics and hydrocarbons; enhances final polishing; not a desalination/recovery step	High operational cost; chemical and energy-intensive	[3,13,21]
Evaporation Ponds (ZLD systems)	>150,000	Very Low (solar/passive) for operations	Very Low	95–99	Enables mineral recovery; Water is NOT recovered; water is removed to atmosphere; concentrates brine/solids (near-ZLD)	Large land footprint; climate-dependent; slow process	[4,35,37,51]
Hybrid UF + RO Systems	10,000–80,000	Moderate (UF pretreatment reduces RO fouling/energy)	High	70–80	Combines advantages of UF and RO; reduces fouling; higher overall recovery	Complex configuration; higher investment cost	[21,22]

Note: Capital costs are approximate and vary with capacity scale and site-specific factors, Energy consumption ranges reflect operational conditions and feed-water quality, Recovery rates are for single-pass operation; multiple passes increase recovery, Hybrid systems combine technologies for enhanced performance.

.

For example, recent studies have proven that flash vaporization systems are highly efficient in reducing salinity levels (>100,000 ppm TDS) [2], a concentration range where membrane technologies become impractical. This solution not only helps in the generation of water that can be reused in agriculture, but also helps in efficiency in water-depleted areas, which in turn goes hand in hand with the boarder sustainable water management goals.

Another noteworthy approach involves the use of evaporation ponds, particularly in the context of potash production. This method facilitates the recovery of useful salts from the rejected water, which can then be utilized in fertilizer manufacturing, thereby linking water treatment to industrial value chains [13,14,15,16,52]. Furthermore, a strong emphasis on sustainability is evident in many current treatment strategies. These include the recycling of treated produced water for agricultural irrigation and the reclamation of salts for industrial reuse, both of which contribute to reducing freshwater dependency and minimizing environmental impact [39].

3.2. Remaining Challenges and Enhancement Opportunities

While current treatment methods for petroleum produced water have demonstrated notable benefits [2], there remains considerable scope for enhancement through the adoption of advanced and integrated technologies:

Firstly, there is a pressing need to expand the focus on advanced oxidation processes (AOPs) and biological treatment methods. These approaches have shown potential in the effective degradation of persistent organic pollutants and the reduction of overall toxicity in wastewater streams. Advanced oxidation, in particular, can complement existing mechanical and thermal methods by targeting contaminants that are otherwise difficult to remove, thereby improving the overall quality of treated water [3].

Secondly, the integration of flash vaporization and evaporation ponds with other complementary technologies warrants further investigation. Combining these thermal methods with biological, chemical, or membrane-based systems may enhance treatment efficiency and reduce operational costs. For example, pre-treating produced water using biological filtration before subjecting it to flash vaporization could lower energy demands, while coupling evaporation ponds with crystallization techniques could increase salt recovery rate from 60–70% to more than 90% and minimize brine waste [20,35,37].

4. Innovative Methods for Integrating Circular Economy Ideas

Flash vaporization offers a state-of-the-art approach for decreasing the salinity of PW [2]. This method uses heat to turn water into vapor, resulting in concentrated brine abundant in valuable salts like potash (KCl) and halite (NaCl). The vaporized water is subsequently condensed and reused for agricultural irrigation, whereas the remaining brine is sent to evaporation ponds [13,14,15,16], where natural evaporation produces potash for fertilizers, fostering a closed-loop system for managing water and salt [53].

Although it requires a lot of energy, flash vaporization has considerable promise for energy recovery. The heat produced during vaporization can be harnessed and redirected to energize other operational systems in petroleum facilities, enhancing overall energy efficiency [43]. Furthermore, incorporating solar energy into evaporation ponds can enhance the reduction in dependency on external energy sources, promoting a more sustainable and economical wastewater treatment process [13,14,15,16,44].

The water obtained via flash vaporization, evaporate shown in Figure 2, post-desalination, can be utilized for agricultural irrigation, presenting a sustainable approach for water conservation in dry areas. This processed water offers a sustainable substitute for freshwater sources, enhancing agricultural output and reducing environmental pressure [41].

Figure 2a shows flash vaporization for the treatment of PW. Hot PW flows into the evaporator, after being preheated, where a drop in pressure leads to vaporization. The steam is subsequently converted into purified water, via condensation, and the excess concentrate is eliminated. Figure 2b illustrates multi-stage flash vaporization for the treatment of PW. Pressure reductions lead to successive vaporization. The vapor is transformed into clean water, while the leftover concentrate is extracted. A recycling loop and pH modification enhance efficiency and water recovery [2].

Flash vaporization presents several key strengths that make it a promising solution for sustainable PW and salt management. It enhances resource efficiency by reclaiming both salts and water from PW, thereby minimizing waste and contributing to a circular economy [54]. The economic advantages of this method are also notable, as it enables the extraction of valuable compounds like potash while repurposing treated water for agricultural use, reducing dependence on freshwater sources and improving overall cost-effectiveness [55]. From a sustainability perspective, flash vaporization supports environmental goals by promoting closed-loop cycles and lowering freshwater consumption [56]. The viability of this technology has been demonstrated through successful pilot projects, highlighting its potential for broader implementation in the oil and gas industry [2,57]. Additionally, energy integration through the use of waste heat and renewable sources such as solar power further reduces energy demands and operational costs [45]. Finally, the scalability of this approach makes it especially suitable for deployment in water-scarce, oil-producing regions, positioning it as a practical and sustainable strategy for managing produced water on a global scale [48].

The study integrates performance data, such as 85–90% water recovery efficiency, 15–25% potash yield, 30–40% halite yield, and energy requirements of 600–800 kWh/m³, to demonstrate the operational effectiveness of the flash vaporization process [58]. Analytical evaluation of process optimization through energy recovery of 25–30% and solar-assisted integration reduce external energy dependence by up to 40%, thereby highlighting potential efficiency improvements and sustainability gains [59]. Additionally, the analysis connects process outcomes to measurable environmental and economic impacts, including a 20–35% reduction in freshwater demand and a 10–15% increase in agricultural productivity [60]. Finally, these innovations are positioned within a closed-loop circular economy framework, emphasizing their techno-economic benefits and the potential scalability of the integrated produced water (PW) treatment system [31].

5. Case Studies and Real-World Applications

Examples of circular economy practices in produced water treatment are shown and briefly discussed in

Table 2. Case Studies on Circular Economy Applications in Produced Water Treatment.

Case Study	Objective	Summary	Company/Operator	Country	Success Factor	Limits	Ref.
CAPCO UF/RO Reclamation (Kaohsiung)	Reclaim fresh water for Purified Terephthalic Acid (PTA) production	Ultrafiltration (UF)/Reverse Osmosis (RO) system recovers nearly 73–75% of produced water, significantly reducing fresh-water intake	CAPCO petrochemical facility in Jubail City	Taiwan	High membrane recovery efficiency; integration into existing industrial water loop	Limited scalability for higher salinity streams	[61,62,63]
PEMEX Minatitlán Refinery	Boiler feed reuse	UF/RO setup treating up to nearly 26,000 m3/d; ~70% overall reuse of waste-water stream	PEMEX refinery	Mexico	Effective reuse for industrial operations; strong corporate support	Energy-intensive pretreatment requirements	[61,64]
ENI Gela Refinery MBR/RO	Groundwater or PW reuse for process water	Combination of Membrane Bioreactor (MBR) and RO achieves ~70% recovery; reject stream treated and discharged safely	ENI Gela Refinery	Italy	Advanced hybrid technology ensures stable output water quality	Requires skilled operation and maintenance	[65]
OriginClear EWS Petro (Bakersfield)	Reuse oil-field PW for steam boilers and irrigation	Electro Water Separation and ultrafiltration removed more than 99.9% turbidity, oil and Total Suspended Solids (TSS), enabling reuse	OriginClear, California oil operator	USA	Excellent removal efficiency; adaptable modular design	Limited long-term field validation data	[66]
Swirltex UF Membrane System	Reuse flowback PW; reduce disposal and emissions	Treated 20,000 bbl/d flowback water; removed TSS, oil, iron ≥ 97% efficiency; cut freshwater use by up to 75%	Swirltex client oil producers	USA	High throughput and mobile deployment	Performance may decline with high organic load	[67]
Genesis Water Technologies (Permian bench)	Treat flowback or produced water for reuse in fracturing	Electrocoagulation + flocculant + micron filtration reduced turbidity < 3 NTU, iron < 1 mg/L, TSS < 1 mg/L for onsite reuse	Large E&P operator in Permian	USA	Cost-effective onsite treatment; customizable for water chemistry	Not ideal for very high salinity produced waters	[68]
Veolia OPUS-II projects (Arroyo Grande/San Ardo)	Eliminate injection; discharge treated PW and reuse for steam	Combined chemical softening, RO and ion-exchange to recover > 75% water; enable aquifer recharge or steam reuse	Veolia + oil field operators	USA	Proven industrial-scale system; regulatory compliance achieved	Limited flexibility for variable flow rates	[36]
Constructed Wetland (Nimr WT Plant)	Natural treatment and reuse for irrigation	Treat 115,000–175,000 m3/day PW via large surface flow wetlands; effluent oil < 0.5 mg/L; biomass valorized	Petroleum Development Oman (PDO)	Oman	Low-cost, nature-based process; supports biodiversity	Unsuitable for compact or urban sites	[69]
Kuwait case hybrid process (gravity separation + membrane + distillation + EOR injection)	Resource recovery and reuse, reduce disposal	Combined filtration, solar distillation & EOR injection yields economic returns, salt sale and fresh water reuse	Kuwait Oil Company/SK Oilfield	Kuwait	Multi-benefit system combining water reuse and resource recovery	Requires consistent sunlight and stable operations	[63]
Oman south-field surface discharge reuse study	Reduce deep disposal, enhance recovery	Produced water reinjection to reverse pressure decline; evaluated surface reuse alternatives	Petroleum Development Oman	Oman	Enhanced oil recovery and reduced disposal	Limited reuse potential for high-salinity PW	[70]
Flash Rockwell ZeroPoint evaporator (Permian)	Eliminate liquid discharge, recover dry solids	Evaporator uses flare gas to convert PW to solids (30,000 gal/day), enabling energy/extraction reuse and low emissions	Flash Rockwell/Permian operators	USA	Zero-liquid discharge; uses waste energy source	Not viable for low gas-availability regions	[71]

. These cases highlight the use of treatment technologies to recover valuable resources while supporting environmental sustainability and economic efficiency. The case study presented below the table discusses the use of CE byproducts for potash production. Potash recovery from produced water faces high scaling potential due to calcium, barium, and sulfate ions that form hard deposits during evaporation. Effective pretreatment and antiscalant use are essential to prevent fouling. The purity of recovered salts depends on brine composition, often requiring multi-stage crystallization to achieve >95% KCl. Optimizing scaling control and crystallization enhances both product quality and process sustainability.

From Table 2 one can understand that almost 30% of PW is converted into wasted rejected brine after treatment. To complete the cycle of circular economy this waste has to be converted into a beneficial product such as potash produced from the Dead Sea. A comparative analysis of key physical and chemical properties of PW, Desalination Rejected Brine, and Dead Sea Water are shown in

Table 3. Comparison of Key Water Quality Parameters: Produced Water, Brine, and Dead Sea [2,13,14,15,16].

Property	Produced Water (Oil & Gas)	Desalination Rejected Brine	Dead Sea Water
Source	Oil and gas production	Reverse osmosis or thermal desalination	Natural hypersaline lake
Salinity (TDS)	10,000–250,000 mg/L	60,000–90,000 mg/L	~340,000–370,000 mg/L
pH	4.5–9.5 (variable)	6.5–8.5	~5.9–6.1
Electrical Conductivity	15–200 mS/cm	70–100 mS/cm	~280–310 mS/cm
Temperature (°C)	25–90 °C (often hot)	25–40 °C	~20–30 °C
Major Ions	Na+, Cl−, Ca2+, Mg2+, SO42−, HCO3−	Na+, Cl−, Mg2+, Ca2+, SO42−	Mg2+, Cl−, Na+, K+, Ca2+, Br−
Dominant Cation	Na+	Na+	Mg2+ (~40–50% of cations)
Dominant Anion	Cl−	Cl−	Cl−
Oil & Grease	Often present (up to 1000 mg/L)	Absent	Absent
Turbidity	High (can be >100 NTU)	Low (<5 NTU)	Low (~2–10 NTU)
Total Organic Carbon (TOC)	Up to 1000 mg/L	<5 mg/L	Very low (~<1 mg/L)
Biological Oxygen Demand (BOD)	Can be high	Very low	Very low
Heavy Metals	May include Ba, Sr, Fe, Zn, Pb	Trace (varies)	Present in trace amounts (Fe, Mn)
Color	Yellow to brown (if oil present)	Clear to slightly yellowish	Clear, may appear murky in depths
Density (g/cm3)	~1.01–1.15	~1.03–1.05	~1.24–1.26

. This comparison is extremely beneficial since the salinity of the formation water is extremely high and so it is more realistic to compare it to Dead Sea Water compared to normal seawater. Also, the treatment of produced water is much more challenging than Dead Sea water [2,13,14,15,16].

It is clear from Table 3 that rejected brine from desalination and Dead Sea water share some notable similarities, primarily their high salinity and limited biological activity. Both are hypersaline solutions: rejected brine typically contains 60,000 to 85,000 mg/L of dissolved salts, while Dead Sea water is significantly more saline, with concentrations around 340,000 to 350,000 mg/L. This extreme salinity in both cases makes them inhospitable to most aquatic life and presents environmental challenges related to disposal or water management. However, their chemical compositions differ substantially. Rejected brine closely resembles concentrated seawater, with sodium chloride (NaCl) as the dominant salt. In contrast, Dead Sea water is geochemically unique, containing exceptionally high levels of magnesium (about 45,000 mg/L), potassium (around 7000 to 10,000 mg/L), calcium, and other minerals, making it far more diverse in ionic content. Additionally, while rejected brine is usually neutral to slightly alkaline in pH, Dead Sea water tends to be slightly acidic (pH 5.5–6). These differences are especially important for applications such as mineral extraction, reuse strategies, or assessing environmental impact.

The Arab Potash Company utilizes Dead Sea water and a solar evaporation pond system to extract its primary raw material, carnallite (KMgCl₃·6H₂O), which is subsequently processed to produce fertilizers for agricultural use [13,14,15,16,38]. The Dead Sea brine is channeled through a series of solar evaporation ponds, where water gradually evaporates, leading to the crystallization of carnallite used to produce fertilizer for agriculture.

The strengths of utilizing flash vaporization and evaporation ponds in PW treatment are multifaceted. Firstly, the case studies highlight their real-world applicability, demonstrating how these technologies can effectively convert PW treatment into a resource recovery process [36,61,62,63,64,65,66,67,68,69,70,71,72]. A key advantage lies in resource recovery, as flash vaporization and potash production transform waste into valuable by-products, supporting industries such as agriculture and chemicals [37]. From an environmental standpoint, these systems promote sustainability by reducing freshwater consumption and minimizing the ecological footprint of PW disposal, while also contributing to sustainable agricultural practices [73]. Economically, the recovery of potash offers an additional revenue stream and helps lower the overall costs related to water treatment and disposal, enhancing the financial viability of these approaches [51]. Flash vaporization requires substantial thermal energy, as the latent heat of vaporization for water is approximately 2.26 MJ/kg, equivalent to about 626 kWh per m³ for complete evaporation. In practice, multistage flash systems with heat recovery reduce this demand to around 70–120 kWh_th·m⁻³, depending on design efficiency and feed salinity. In comparison, Multiple-Effect Distillation (MED) systems typically consume slightly less thermal energy, averaging 60–80 kWh_th·m⁻³, due to improved internal heat reuse. Reverse Osmosis (RO), on the other hand, operates electrically with far lower energy needs of 3–5 kWh_e·m⁻³, making it more efficient for desalination but unsuitable for solid salt recovery. When thermal energy is converted to its electrical equivalent, flash vaporization remains several times more energy-intensive than RO. However, if powered by waste heat or solar thermal energy, its economic feasibility improves significantly. Energy requirements rise sharply with brine concentration, as higher salinity increases boiling point elevation and reduces vaporization efficiency. Hybrid RO–thermal systems can balance these trade-offs by using RO for primary desalination and flash vaporization for final concentration and potash crystallization. Overall, while flash vaporization is energy-demanding, it remains the most practical route for zero liquid discharge and salt recovery applications in produced water management [36,37,51,62,63,64,65,66,67,68,69,70,71,72,73].

6. Scalability, Sustainability, and Regulatory Pathways for Economic Viability

6.1. Scalability and Economic Viability

The study would improve with a more thorough examination of the expenses linked to the adoption of flash vaporization and potash recovery technologies, such as infrastructure and resource recovery [46]. Extensive implementation necessitates significant financial investment, which can differ based on site-specific factors like PW chemistry and operational scale [47]. Moreover, examining the financial benefits of reusing treated water and generating potash would aid in evaluating overall feasibility, as research has indicated that potash recovery can greatly reduce wastewater management expenses [40]. The application of sophisticated membrane technologies in conjunction with these approaches could additionally improve efficiency and reduce costs [42]. For example, capital costs for installing a flash vaporization system typically range between USD 1000–2000 per m³/day of treatment capacity, depending on the degree of heat recovery and automation, while operating costs are estimated at USD 2–4 per m³ due to high energy demand. In contrast, membrane-based systems like reverse osmosis have lower capital expenditures of around USD 500–1000 per m³/day and operational costs of USD 0.5–1.5 per m³, though they produce brine that still requires disposal. When integrated with potash recovery, flash vaporization can yield additional economic returns; for example, the recovery of 1 ton of KCl from produced water (with 10–20 g/L K⁺) could generate USD 250–350 in market value, partially offsetting energy and maintenance costs. Large-scale evaporation ponds further add USD 0.5–1.0 million per hectare in construction costs but offer the advantage of low operational expenditure and potential by-product recovery. Cost–benefit analyses indicate that systems coupling treated-water reuse for irrigation or industrial cooling with potash recovery can reduce total wastewater management expenses by up to 40–60% compared to conventional deep-well injection. The incorporation of advanced membrane pre-treatment before flash vaporization can also reduce energy demand by 15–25%, improving overall process economics. These figures suggest that, despite high upfront costs, hybrid flash–membrane–recovery configurations may offer long-term financial viability, especially in regions where fresh water and fertilizers hold significant economic value [40,42,46,47,51].

The circular economy model for managing produced water offers both environmental and economic advantages. By applying flash vaporization to produce agricultural-quality water and recovering potash and other mineral fertilizers from the remaining brine, this approach can create new revenue streams that help balance treatment costs. Recent studies suggest that recovering valuable resources from produced water can lower disposal costs and enhance project economics, especially when implemented at scale [74,75,76]. In parallel, market analyses indicate that global demand for potash continues to grow, driven by the need for sustainable fertilizer production and increased agricultural output [77,78]. While a detailed techno-economic analysis is beyond the scope of this review, available data show that the capital and operating costs of integrated recovery systems can be comparable to, or even lower than, traditional disposal methods, particularly when renewable energy or waste heat is used for vaporization [79,80]. Overall, this approach illustrates how circular management can turn produced water from an environmental burden into an economic opportunity, linking technical feasibility with sustainability and market potential.

6.2. Long-Term Sustainability

Elaborating on the long-term effects of these technologies, such as life cycle evaluations and their socio-economic impacts on nearby communities, would offer a broader perspective on their sustainability [22]. The environmental impact of flash vaporization and evaporation ponds needs to be evaluated in comparison to other wastewater treatment options to establish their feasibility [21]. Additionally, research indicates that incorporating renewable energy sources like solar or wind can greatly lower operational expenses and carbon emissions, enhancing the sustainability of the process [3]. The use of treated produced water in industrial or agricultural settings may enhance regional water security [4]. The environmental impact of flash vaporization and evaporation ponds needs to be evaluated in comparison to other wastewater treatment options to establish their feasibility [21]. Membrane-based systems, such as reverse osmosis and nanofiltration, generally have lower energy requirements and smaller physical footprints, but they generate concentrated brine streams that still require disposal or further treatment, and membrane fouling can raise long-term operational costs. Advanced oxidation processes (AOPs), including ozonation and photocatalysis, are effective for degrading organic pollutants and hydrocarbons but are limited by high chemical and energy demands, making them less suitable for large-volume produced water applications. Biological treatments, such as constructed wetlands or membrane bioreactors, offer eco-friendly and cost-effective options for organic load reduction; however, they are sensitive to high salinity and toxic constituents commonly found in produced water, which restricts their scalability. From a life cycle perspective, flash vaporization and evaporation ponds exhibit higher initial energy footprints but can achieve complete water and resource recovery, contributing to circular economy goals. Their socio-economic benefits include potential job creation in rural areas through pond management and salt recovery, as well as improved regional water security when treated water is reused for agriculture or industry. Incorporating renewable energy sources, such as solar or wind, into these systems can substantially reduce operational costs and carbon emissions, positioning thermal treatment as a sustainable solution when integrated within a broader resource recovery framework [21].

6.3. Regulatory Framework

A conversation about the regulatory challenges and policies required to promote these circular economy strategies would be insightful, particularly considering the regional variations in wastewater treatment regulations [39]. Nations with strict environmental regulations possess more advanced systems for promoting wastewater recycling, while some still do not have specific protocols for handling and discharging produced water [81]. For instance, the United States regulates produced water management under the Environmental Protection Agency’s (EPA) Clean Water Act, which mandates strict discharge limits and encourages reuse in certain basins, while Saudi Arabia’s Ministry of Environment, Water, and Agriculture has recently introduced frameworks emphasizing produced water reuse for industrial and agricultural applications. Costs associated with regulatory compliance can pose considerable financial strain, influencing the overall economic viability of recovering potash from produced water waste [46]. Tackling these challenges necessitates cooperation between industry participants and policymakers to create standards that reconcile economic and environmental goals [47]. Moreover, government incentives and grants might expedite the implementation of sustainable water treatment technologies within the oil and gas industry [40].

6.4. Strategic Stakeholder Recommendations

The translation of technical and economic analyses into implementation roadmaps should include their specific guidance to the stakeholders that will addresses the distinct needs, constraints and decision-making requirements that the researchers, industry practitioners, and policymakers have.

To facilitate this translation,

Table 4. Stakeholder-specific strategies for advancing circular economy implementation in produced-water management through innovation, operations, and policy alignment.

Stakeholder	Strategic Focus	Key Actions/Recommendations
Researchers	Advance sustainable treatment innovation	- Develop low-energy hybrid desalination systems integrating solar or waste-heat recovery. - Establish coherent life-cycle assessment frameworks that link energy, water, and material efficiency. - Investigate selective extraction of critical minerals (Li, Sr, etc.) to enhance circular resource value. - Apply predictive modelling tools to improve membrane performance and reduce fouling risk. - Standardize produced water sampling and analytical protocols to strengthen data comparability and reproducibility.
Industry Practitioners	Operational integration and risk management	- Conduct pilot testing under field conditions to validate design performance before full-scale deployment. - Prioritize sites with substantial volumes and high salinity, where reuse potential and low-cost energy sources enable favorable economics. - Employ modular, scalable designs that allow phased expansion and technology refinement. - Maintain enhanced water-quality monitoring programs exceeding regulatory requirements to build transparency and trust. - Engage agricultural and industrial stakeholders early and pursue co-location with downstream sectors to create operational synergies.
Policymakers	Regulatory and financial enablement	- Develop differentiated, risk-based reuse standards aligned with intended end-uses. - Provide fiscal incentives and green finance instruments to encourage circular water investments. - Mandate comprehensive life-cycle environmental assessments for major projects. - Support public–private pilot partnerships and promote harmonized regional regulation to streamline adoption. - Integrate circularity and resource-recovery metrics into national sustainability and reporting frameworks.

Note: The strategic focus and key recommendations were combined from the analysis of case studies (Section 5, Table 2), a comparative evaluation of treatment technologies (Section 3.1), economic viability assessment (Section 6.1), and an examination of regulatory frameworks (Section 6.3).

outlines a brief framework of strategic priorities and specific actions for each stakeholder group based on the findings of the literature reviewed and empirical case evidence.

7. Empowering Talent to Drive Circular Economy in Produced Water Treatment

Talent development plays a pivotal role in advancing the circular economy within produced water treatment. One key strength lies in enhancing technological innovation, as a well-trained workforce is capable of developing and applying advanced treatment methods such as membrane filtration, AI-driven monitoring, and bioremediation techniques [25,80,82]. Encouraging cross-disciplinary expertise further empowers engineers and scientists to merge knowledge from chemistry, data science, and environmental engineering, enriching water management strategies. In terms of operational gains, skilled professionals contribute to cost efficiency and sustainability by optimizing treatment processes to reduce chemical use, energy consumption, and waste disposal costs [83,84]. Moreover, such expertise enables companies to reuse treated water, decreasing reliance on freshwater sources and mitigating environmental impacts. Another significant strength is the promotion of industry–academia collaboration. Partnerships between corporations and universities support innovation in water recycling, with industry-funded programs advancing specialized training in areas such as desalination, nanotechnology, and AI-driven water analytics [49,50]. Talent development also bolsters regulatory compliance and ESG (Environmental, Social, and Governance) performance. Training initiatives ensure that environmental professionals stay informed about both global and local water regulations, enabling companies to meet sustainability goals like Saudi Vision 2030 and Net Zero targets [85,86]. Furthermore, digitalization enhances training and operations through tools such as Virtual Reality (VR) and Augmented Reality (AR), offering immersive learning experiences in managing water systems, while AI-driven platforms aid in honing predictive modeling and process optimization skills [87,88]. Lastly, future-proofing the workforce is essential as the oil and gas sector transitions toward sustainable models. Upskilling employees in circular economy principles ensures long-term adaptability and career growth, with certifications in green chemistry, water treatment, and environmental engineering preparing professionals for emerging roles in sustainable energy and resource management [89,90].

8. Lifecycle Environmental Impact of the Circular Economy Model for Produced Water

Assessing the environmental impact of a circular economy model for produced (formation) water requires examining the entire lifecycle, from collection and treatment to reuse and final application. This approach offers clear benefits by reducing freshwater demand and minimizing waste disposal [22,75,91]. However, it also introduces environmental challenges that must be carefully managed.

A key concern is the carbon footprint of energy-intensive treatment processes, particularly thermal methods such as vaporization and distillation. These processes consume substantial energy, and when powered by fossil fuels, they contribute significantly to greenhouse gas emissions [3,92]. Integrating renewable energy sources or utilizing waste heat recovery systems can help reduce emissions and improve overall sustainability [3,93].

Another important issue is the potential contamination of soil and groundwater, especially when evaporation ponds are used to concentrate or dispose of produced water. Poorly lined or inadequately maintained ponds can allow salts, heavy metals, and hydrocarbons to infiltrate the subsurface environment [39,94]. To mitigate these risks, the model should include robust containment systems, regular environmental monitoring, and zero-liquid discharge (ZLD) technologies that prevent direct discharges [8].

The circular economy model redefines produced water as a valuable resource rather than waste; however, its long-term sustainability relies on the adoption of low-carbon energy solutions, advanced treatment technologies, and robust environmental safeguards throughout the entire lifecycle [74,75].

9. Conclusions

This review demonstrates that applying circular economy (CE) frameworks to petroleum produced water (PW) management can transform one of the industry’s largest waste streams into a sustainable resource cycle. The integration of flash vaporization with evaporation pond crystallization achieves near-zero liquid discharge, yielding high-quality irrigation water and valuable mineral by-products such as potash and halite. Collectively, these innovations enable up to 80% reduction in PW disposal, 25–30% lower greenhouse gas emissions, and 20–35% cost savings compared to conventional treatment and disposal methods. Although high energy demand and capital intensity remain challenges, coupling thermal systems with renewable energy, waste-heat recovery, and membrane pre-treatment can significantly enhance process efficiency. Long-term sustainability depends on regulatory support, economic incentives, and cross-sector collaboration linking oil producers, agricultural stakeholders, and policymakers. Future work should focus on optimizing hybrid low-energy technologies, conducting full life-cycle assessments, and quantifying social and environmental co-benefits. By aligning economic viability with environmental responsibility, CE-based PW management represents a practical, scalable model for advancing global sustainability and resource stewardship in the petroleum sector.