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Article

Wastewater Treatment Plant Upgrade and Its Interlinkages with the Sustainable Development Goals

by
Laila A. Al-Khatib
1,* and
Ahmad M. AlHanaktah
2
1
Environmental Engineering Department, Faculty of Engineering, Al-Hussein Bin Talal University, P.O. Box 25, Ma’an 71111, Jordan
2
Laboratories and Quality Department, Aqaba Water Company, P.O. Box 252, Aqaba 77110, Jordan
*
Author to whom correspondence should be addressed.
Resources 2025, 14(4), 62; https://doi.org/10.3390/resources14040062
Submission received: 12 March 2025 / Revised: 30 March 2025 / Accepted: 3 April 2025 / Published: 8 April 2025
(This article belongs to the Special Issue Editorial Board Members' Collection Series: Water Resources)
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Abstract

:
In the face of acute water scarcity and sanitation challenges emblematic of arid and semi-arid regions (ASARs), this study investigated the transformative upgrade of the Aqaba Conventional Activated Sludge Wastewater Treatment Plant (CAS-AWWTP) in Jordan. The project, expanding capacity to 40,000 m3/day, integrated sustainable features including renewable energy and repurposed natural treatment ponds functioning as artificial wetlands. The plant’s treatment performance, byproduct valorization, and alignment with sustainable development goals (SDGs) were assessed. Comparative analysis revealed that the upgraded CAS-AWWTP consistently outperforms the previous natural and extended activated sludge systems. CAS-AWWTP average removal efficiencies of BOD5, COD, TSS, and T-N were 99.1%, 96.6%, 98.7%, and 95.1%, respectively, achieving stringent reuse standards and supplying approximately 30% of Aqaba Governorate’s annual water budget, thus conserving freshwater for domestic use. Furthermore, the plant achieved 44% electrical self-sufficiency through renewable energy integration, significantly reducing its carbon footprint. The creation of artificial wetlands transformed the site into a vital ecological habitat, attracting over 270 bird species and becoming a popular destination for birdwatching enthusiasts, drawing over 10,000 visitors annually. This transformation underscores the plant’s dual role in wastewater treatment and environmental conservation. The AWWTP upgrade exemplifies a holistic approach to sustainable development, impacting multiple SDGs. Beyond improving sanitation (SDG 6), it enhances water reuse for agriculture and industry (SDG 6.4, 9.4), promotes renewable energy (SDG 7), stimulates economic growth (SDG 8), strengthens urban sustainability (SDG 11), fosters resource efficiency (SDG 12), and supports biodiversity (SDG 14/15). The project’s success, facilitated by multi-stakeholder partnerships (SDG 17), provides a replicable model for water-scarce regions seeking sustainable wastewater management solutions.

1. Introduction

Water scarcity and inadequate sanitation are critical global challenges, particularly in arid and semi-arid regions (ASARs), which comprise approximately 40% of the Earth’s land surface and are home to over two billion people [1,2]. These regions face chronic water shortages due to limited rainfall, high evaporation, and constrained renewable resources [3]. Exacerbating these natural limitations are anthropogenic pressures like population growth, urbanization, and agricultural intensification, which strain existing water infrastructure [4]. Climate change, with its altered precipitation patterns and increased frequency of droughts, further compounds these challenges [5]. A holistic approach, integrating innovative water management, advanced wastewater treatment technologies, and sustainable practices, is essential for addressing water scarcity in ASARs. Effective wastewater management is particularly crucial, offering a reliable alternative water source while simultaneously mitigating environmental pollution [6].
Jordan, recognized as one of the world’s most water-scarce countries, exemplifies the urgent need for such integrated solutions. The country’s precarious water situation is starkly illustrated by its critical water stress level, reaching approximately 103%, significantly exceeding the global average of 18.6% and the already high regional average for the Middle East and North Africa (MENA) of approximately 80% [7]. Despite this extreme scarcity, compounded by the challenges of hosting a large refugee population, Jordan has made notable strides in improving access to safe drinking water and sanitation services. The country has demonstrated the fastest improvement in safely managed drinking water services coverage in Western Asia and is on track to achieve SDG 6 by 2030 [8,9]. This progress, driven by expanding non-piped water solutions and improving sanitation infrastructure, highlights Jordan’s commitment to sustainable water resource management, including increased water-use efficiency in irrigation and the reuse of treated wastewater.
Optimizing urban water systems, particularly wastewater treatment plants (WWTPs), is a global priority. WWTPs play a vital role in maintaining water quality and enabling resource recovery in the face of climate change, the water–energy–food nexus, and evolving regulatory requirements [10].
To mitigate the adverse environmental and public health impacts of untreated wastewater, a diverse array of treatment methodologies has been developed. These methods encompass physical processes like sedimentation and filtration, chemical processes such as coagulation and disinfection, and biological processes that harness the metabolic capabilities of microorganisms [11]. Among these, biological treatment, particularly the activated sludge process (ASP), has emerged as a cornerstone of modern wastewater treatment plants (WWTPs) due to its efficacy in removing organic pollutants and nutrients.
The ASP utilizes a suspended microbial community to degrade organic matter in an aeration basin, followed by solid–liquid separation in a secondary clarifier. This process has been widely adopted globally due to its relatively low operational cost, high treatment efficiency, and robustness in handling fluctuating wastewater compositions [12,13,14]. It often can be enhanced with advanced oxidation, sorption, and filtration technologies [15,16,17]. Several countries, such as Switzerland and China, have already implemented such upgrades, incorporating technologies like ozonation, activated carbon, and membrane filtration to address micropollutants, enable gray water recycling, and reduce nutrient discharge [17,18,19]. Technological advancements also encompass optimizing aeration systems, utilizing advanced control strategies, and implementing anaerobic digestion for biogas production, contributing to energy recovery and reducing operational costs [20].
Furthermore, effective water management is fundamental to achieving the Sustainable Development Goals (SDGs), especially given that 11 of the 17 SDGs are directly linked to access to clean water [21]. Improved WWTP performance significantly contributes to this goal. By enabling safe water reuse, reducing pollution, and enhancing overall water quality, WWTPs directly support SDG 6 (Clean Water and Sanitation) and SDG 3 (Good Health and Well-being) [22,23]. Moreover, they contribute to SDG 11 (Sustainable Cities and Communities), SDG 12 (Responsible Consumption and Production), SDG 13 (Climate Action), and SDG 14 (Life Below Water) [8,22].
This research presents a case study of the recent expansion and rehabilitation of the North Aqaba wastewater treatment plant (AWWTP) in Jordan. This significant project has increased treatment capacity from 21,000 m3/day to 40,000 m3/day, benefiting approximately 150,000 people and improving sanitation services in Aqaba. The project incorporated sustainable elements, including renewable energy integration (biogas and photovoltaics), sludge treatment, and repurposed natural treatment ponds for treated wastewater storage and ecosystem preservation. This upgrade was designed to enhance effluent quality for non-potable reuse, thereby increasing water availability and contributing to water security and sustainable development in Jordan [24].
Existing literature on WWTPs encompasses process optimization [25], quality assessment against standards [26], and comparative sustainability analyses, particularly concerning emerging technologies and their alignment with the SDGs [22]. This study, however, undertakes a comprehensive performance assessment of the expanded AWWTP, evaluating pollutant removal efficiency and compliance with stringent effluent discharge standards. Critically, this research links the tangible results of the plant expansion to specific SDG targets. By rigorously assessing AWWTP performance and linking findings to the SDGs, this study provides valuable data and insights, focusing on maximizing resource recovery and promoting sustainable water management practices that demonstrably advance multiple SDGs.

2. Materials and Methods

This study investigates the performance of the AWWTP, located in Aqaba City, Jordan. The AWWTP has undergone several significant upgrades throughout its operational history. Initially commissioned in 1986, the plant utilized a natural treatment system consisting of a series of facultative and maturation ponds with a treatment capacity of 9000 m3/day. In 2005, the AWWTP was expanded to incorporate a mechanical extended aeration-activated sludge system, increasing the treatment capacity to 12,000 m3/day alongside the existing natural treatment system. Most recently, in 2022, the AWWTP underwent a major transformation, shifting to a conventional activated sludge treatment technology. This upgrade, facilitated by the Aqaba Water Company with support from USAID and the German Agency for International Cooperation (GIZ), decommissioned the natural pond system and significantly increased the plant’s capacity to 40,000 m3/day [24].

2.1. Conventional Activated Sludge Wastewater Treatment Plant Process Description

The Conventional Activated Sludge Wastewater Treatment Plant (CAS-AWWTP) is composed of three distinguishable lines: a wastewater line, sludge line, and power line, as illustrated in Figure 1. The wastewater line is composed of four main stages including (i) preliminary treatment, involving screening, grit, and oil removal to prevent damage to equipment; (ii) primary treatment including sedimentation processes for the removal of floating and settleable solids from wastewater in sedimentation tanks; and (iii) secondary treatment involving activated sludge processes (aerobic oxidation ditch reactors) for the oxidation of organic matter and nitrification. In addition, the biological reactors in CAS-AWWTP include anoxic reactors to create a denitrification process. The biological treatment process is utilized for the removal of biodegradable organic matter and biological nutrient removal. Finally, (iv) a tertiary treatment consists of the combined operation of the coagulation-flocculation units, the disc filter, and disinfection by a gas chlorination system to achieve enhanced removal of residual organic matter, phosphorus, and enteric microorganisms from the wastewater. The sludge line includes units for sludge thickening, sludge mixing, anaerobic digestion, and dewatering. Biogas recovered after sludge anaerobic digestion allows the production of energy. Furthermore, to ensure sustainable operation, the power line in the plant employs a hybrid renewable energy system. This system integrates biogas generated from anaerobic digestion with photovoltaic (PV) solar power. Anaerobic digestion is carried out in two 4500 m3 digesters, utilizing gas injection. The resulting biogas is treated and stored in a 500 m3 tank before fueling three 311 kW combined heat and power (CHP) engines (cogeneration) [27]. Complementing the biogas system, a 2.3 MW solar PV plant contributes to the plant’s electricity needs. These combined renewable energy sources power both the treatment processes and the pumping of treated water for reuse. This dual power generation approach positions the plant as a pioneer project in Jordan, significantly reducing its reliance on the public electricity grid.
During the plant’s most recent expansion, a two-tiered odor-control strategy was implemented. For the water treatment line, a biological odor-control system was installed. This approach eliminates the need for chemical odor control, enhancing plant safety and reducing operational costs. For the sludge treatment line, carbon filters are employed to remove odorous air extracted from the sludge building.
After completing the construction of the expansion of this wastewater treatment plant, the natural treatment ponds were emptied, cleaned, and maintained. These ponds were rehabilitated and are used for the storage of treated effluent. Furthermore, the effluent from the CAS-AWWTP is used to feed the ponds to serve as artificial wetlands, which have developed into a well-known bird habitat and a tourist attraction as a bird observatory site.

2.2. Analytical Methods

Influent and effluent samples were collected and analyzed to assess the performance of the wastewater treatment plant. The following key performance indicators were measured in accordance with established standard methods [28]: 5-day biochemical oxygen demand (BOD5), chemical oxygen demand (COD), total dissolved solids (TDSs), total suspended solids (TSSs), turbidity (Turb.), total nitrogen (T-N), bicarbonate (HCO3), nitrate (NO3), ammonium (NH4), pH, nematode Eggs (N. Eggs), and Escherichia coli (E. coli) concentrations. These parameters were selected to provide a comprehensive evaluation of treatment efficiency, encompassing organic matter removal, solids reduction, nutrient removal, and microbial removal. To evaluate the impact of the plant upgrade, historical operational data were compiled and analyzed. Data from the previous treatment processes, encompassing the natural and extended mechanical treatment plants, were collected for the period 2019–2021. This dataset provides a baseline against which to compare the performance of the upgraded plant. Data for the current CAS-AWWTP were collected for the period 2022–2023, representing the operational period following the upgrade. This comparative analysis allowed for a quantitative assessment of the improvements achieved in wastewater treatment performance as a result of the upgrade.

2.3. Removal Efficiency

Removal efficiency (R) is usually used as an indicator to assess the wastewater treatment plant’s efficiency. The concentrations of the assessed parameters in the wastewater influent (Cinf) and effluent (Ceff) were utilized to determine the removal efficiency using Equation (1) [29].
R = C i n f − C e f f   C i n f × 100

2.4. Jordanian Standard JS 893-2021

Jordan maintains rigorous safety measures and controls for wastewater reuse, representing some of the most advanced practices in the region. The country’s first wastewater reuse standard, developed in accordance with World Health Organization guidelines, was published in 1991 and revised in 2006 and most recently in 2021 (JS 893/2021 [30]) to become more stringent. This standard establishes and regulates allowable pollutant concentrations in treated wastewater, differentiating requirements based on end-use applications and reuse conditions. Specifically, the standard is divided into two sections: one addressing treated wastewater discharge into wadis (valleys) and water bodies, and the other outlining effluent quality requirements for various reuse purposes. The reclaimed water for reuse is further divided into reuse for groundwater artificial recharge and reclaimed water reuse for irrigation. The latest revision introduced stricter requirements for key pollutants, notably BOD5, COD, TSS, NO3, and PO4, especially concerning wastewater reuse in irrigation. Specifically, allowable NO3 and PO4 limits were reduced from 30 to 16 mg/L and from 30 to 10 mg/L, respectively. BOD5 limits for Class B decreased from 200 to 100 mg/L, and for Class C, they decreased from 300 to 200 mg/L. COD limits, previously 500 mg/L for both Class B and C, were revised to 200 mg/L for Class B and 300 mg/L for Class C. Similarly, TSS limits were lowered from 200 to 100 mg/L for Class B reuse and from 150 to 100 mg/L for Class C.

2.5. AI Tool Use

During the preparation of this work, the authors used the bibliography software package (Zotero 6.0.36) for reference management. Also, Quillbot v19.8.3 was employed for language editing, specifically to check grammar and spelling. After using these tools, the authors reviewed and edited the content as needed.

3. Results and Discussion

3.1. Assessment of AWWTP Performance

The AWWTP underwent a significant upgrade, transitioning from a combination of natural and extended activated sludge systems to a single, advanced conventional activated sludge plant. Table 1 and Figure 2 present a comparative analysis of the treatment performance across these three plant configurations, focusing on key indicators: BOD5, COD, TSS, and (T-N).
Organic matter is a key component of wastewater, and its effective removal, often measured through parameters like BOD5 and COD, is crucial for successful wastewater treatment plant operation. The removal of organic matter shows significant reductions from influent to effluent in all plants. Influent BOD5 concentrations were relatively consistent ranging from 343.0 ± 59.7 to 408.5 ± 110.2 mg/L across the three plants. However, the effluent BOD5 concentrations demonstrated a clear improvement with each upgrade. The natural treatment plant achieved a mean effluent concentration of 34.3 ± 8.8 mg/L, while the extended activated sludge plant significantly improved performance with a mean of 4.3 ± 1.4 mg/L. The conventional activated sludge plant demonstrated the highest treatment efficiency, achieving an exceptionally low mean effluent BOD5 of 3.6 ± 1.1 mg/L. Corresponding removal rates were 90.0%, 98.7%, and 99.1% for the natural, extended activated sludge, and conventional activated sludge plants, respectively. This progression highlights the superior performance of advanced treatment technologies in removing biodegradable organic matter.
A similar trend was observed for COD, another key indicator of organic content. The CAS-AWWTP achieved a 96.6% removal rate, significantly outperforming the natural (54.8% removal) and extended activated sludge (95.8% removal) systems. This further emphasizes the greater effectiveness of mechanical treatment, particularly for the CAS plant, in removing organic pollutants, including fewer biodegradable compounds, as measured by COD. The substantial difference in COD removal between the natural and the activated sludge systems suggests the increasing importance of mechanical aeration and biological treatment for the removal of more complex organic substances [31,32,33]. This improvement can be attributed to the optimized design and operation of the CAS system, including controlled aeration, mixed-liquor suspended-solids concentration, and hydraulic retention time [31,34,35]. Compared to other studies, the removal efficiency achieved by the CAS-AWWTP is within the typical range reported for well-operated conventional activated sludge systems. In comparison, [25] achieved a high BOD removal efficiency of 98.7%, while [26] reported removal efficiencies of up to 95% for BOD5 and 93% for COD.
Regarding suspended solids, as measured by TSS, the CAS-AWWTP demonstrates the highest removal efficiency, achieving a 98.7% removal. This contrasts sharply with the natural treatment plant (R = 39.2%) and is similar to the extended activated sludge (R= 98.7%) plant. While both the extended and conventional activated sludge systems demonstrated similar TSS removal efficiencies, the conventional system’s superior COD removal suggests a greater capacity for removing complex organic compounds that may contribute to both COD and TSS. This indicates that the CAS-AWWTP is more effective in removing both particulate and colloidal organic matter [36]. The substantial difference in TSS removal between the natural and advanced treatment systems underscores the technological advancements in particulate matter removal and the importance of solid–liquid separation in achieving high effluent quality.
Nutrient abatement, particularly nitrogen and phosphorus removal, is crucial in modern wastewater treatment due to their significant impact on aquatic environments and increasingly stringent discharge regulations [26]. Nitrogen removal, a critical factor in mitigating eutrophication, further emphasizes the improved performance of the CAS-AWWTP. This system achieved 95.1% total nitrogen (T-N) removal, substantially higher than the 37.8% removal observed in the natural treatment plant and exceeding the 91% removal achieved by the extended activated sludge plant. This significant difference in nitrogen removal efficiency likely served as a key regulatory driver for the plant upgrade, as nitrogen removal is frequently a primary target in wastewater treatment regulations. The enhanced nitrogen removal in the CAS-AWWTP can be attributed to the optimized nitrification and denitrification processes within the activated sludge system, likely involving a dedicated anoxic zone for denitrification [37]. The achieved T-N removal efficiency of CAS-AWWTP (95.1%) exhibited a higher value than that reported by [26] (86.5%).
While all three methods demonstrated a reduction in pollutant levels from influent to effluent, the CAS-AWWTP emerged as the most effective across all measured parameters. CAS systems offer a more controlled, efficient, and versatile approach to wastewater treatment compared to natural techniques. Furthermore, the lower standard deviations for the CAS-AWWTP in most parameters indicated more stable and consistent treatment performance, crucial for long-term environmental protection. While natural systems can be a viable option in certain situations (for example, small communities and decentralized treatment), CAS systems are generally preferred for larger-scale applications where high treatment efficiency, consistent performance, and the removal of a wide range of pollutants are required [38,39]. The transition to the CAS system represents a significant advancement in treatment efficacy, enabling the plant to meet more stringent effluent quality standards and minimize its environmental impact.

3.2. CAS-AWWTP Effluent Assessment for Reuse Purposes

The primary objective of the wastewater treatment plant is to generate high-quality effluent suitable for both environmentally sound discharge into natural systems and safe reuse for various applications. Prior to reuse or discharge, effluent water quality must meet specific standards and align with its intended end-use [26]. The Aqaba sewage system, encompassing the collection network and wastewater treatment plant, is designed to treat municipal wastewater to comply with the requirements for treated water reuse in irrigation. Table 2 and Figure 3 present the mean concentrations of the effluent’s physical, chemical, and biological quality parameters from the three treatment systems and the allowable concentration of the different reclaimed water indicators for reuse in irrigation according to JS 893:2021 [30]. A comparison of the mean wastewater characteristics for each treatment plant against JS 893:2021 [30] for reclaimed water reuse in irrigation revealed distinct performance differences. The natural treatment plant’s effluent failed to meet the standards for any of the four reuse classes (A, B, C, and D), exceeding the allowable limits for several key parameters such as BOD5, COD, and TSS. The extended activated sludge plant demonstrated improved performance, achieving compliance with the standards for Class B and C irrigation, but failed to meet the stricter standards for Class A and D. In contrast, the upgraded CAS-AWWTP consistently met all reclaimed wastewater requirements for agricultural reuse across all four classes.
This progression in performance from the natural to the extended activated sludge to the CAS plant highlights the increasing effectiveness of each technology in meeting the stringent JS 893:2021 standard [30] and underscores the significant improvement achieved by the CAS plant upgrade. In addition, the data emphasize the importance of advanced treatment technologies in achieving compliance with stringent water reuse standards, particularly for unrestricted irrigation purposes, ensuring better protection of the receiving environment. Furthermore, consolidating operations into a single, more efficient system likely reduces operational complexities and associated maintenance costs compared to managing two separate treatment processes.
As mentioned before in Section 2.4, the latest Jordanian standard revision introduced stricter requirements for key pollutants. This regulatory update underscores the significance of the AWWTP upgrade, as it enhances treated wastewater quality to meet these more stringent standards. By achieving compliance with JS 893:2021 [30], the upgraded plant supports the continued sustainable reuse of wastewater for irrigation while safeguarding both the environment and public health.
CAS-AWWTP plays a crucial role in water resource management for Aqaba, demonstrating the viability of reclaimed wastewater for restricted agricultural irrigation and industrial applications. In 2022, the plant processed over 8 million cubic meters of raw wastewater, averaging 22,500 ± 1794 m3/day, and yielded approximately 19,500 ± 1226 m3/day of reclaimed water. Upgrades and expansion efforts have significantly enhanced effluent quality, establishing the CAS-AWWTP effluent as a reliable alternative water source.
The reclaimed water is strategically allocated, with approximately 70% (13,800 m3/day) dedicated to irrigation and 30% (5660 m3/day) to industrial use, primarily within the phosphate industries. Daily reuse volumes ranged from 17,143 to 20,846 m3/day (Figure 4). This effectively showcases the potential of improved wastewater treatment infrastructure to address water scarcity challenges. This sustainable reuse practice is projected to increase freshwater availability for Aqaba households by 25% [40], offering substantial social and environmental benefits. Furthermore, it supports the region’s economic growth by implementing a circular economy approach, transforming wastewater into a valuable resource. This case study highlights the significant contribution of wastewater reuse and recycling in alleviating pressure on water resources and promoting environmental sustainability, thereby advancing the objectives of Sustainable Development Goal 6 (Clean Water and Sanitation).

3.3. Transformative Impact on SDGs

The AWWTP upgrade transcends conventional wastewater management, serving as a powerful catalyst for achieving multiple SDGs, showcasing a truly holistic approach to sustainable development. While its primary alignment with SDG 6 (Clean Water and Sanitation) is evident, the project’s ripple effects extend across a complex web of interconnected goals, demonstrating the profound impact of integrated resource management.

3.3.1. SDG 6: Securing Water Resources in a Water-Scarce Region

The upgrade has significantly improved access to safely managed sanitation (Target 6.2) for approximately 150,000 residents, a critical advancement in a region where water scarcity is a defining challenge. The reclaimed water now contributes a substantial 30% to Aqaba Governorate’s annual water budget. This injection of a reliable, alternative water source is not merely a quantitative increase; it represents a qualitative shift in water security, mitigating the vulnerabilities inherent in arid environments. Furthermore, the advanced tertiary treatment processes significantly enhance water quality and reduce pollution (Target 6.3), ensuring compliance with stringent national standards and safeguarding downstream ecosystems. The strategic expansion of water reuse (Target 6.4) is pivotal, transforming wastewater from a liability to a valuable resource. Irrigation of green spaces, including the Ayla Oasis project’s golf courses, exemplifies this, not only conserving precious freshwater but also actively combating desertification and fostering eco-tourism [41]. This synergy between water management, environmental rehabilitation, and economic diversification underscores the project’s transformative potential.

3.3.2. SDG 9 and 12: Driving Industrial Sustainability and Resource Efficiency

Beyond tourism, the AWWTP upgrade has become a cornerstone of industrial sustainability. The Jordan Phosphate Mining Company (JPMC) Industrial Complex’s reliance on reclaimed water for 50% of its needs demonstrates a paradigm shift toward resource-use efficiency (Target 9.4) [42]. This industrial symbiosis not only conserves freshwater but also promotes the adoption of clean and environmentally sound technologies, fostering a circular economy model. The efficient recycling and reuse of treated water (Target 12.2) minimizes waste and maximizes resource utilization, showcasing a proactive approach to sustainable consumption and production patterns. The nutrient-rich reclaimed water also holds the potential to reduce reliance on chemical fertilizers in agriculture [43,44], contributing to SDG 2 (Zero Hunger) while simultaneously alleviating pressure on freshwater resources.

3.3.3. SDG 7 and 13: Renewable Energy Integration and Climate Action

The AWWTP’s integration of renewable energy solutions, specifically biogas and photovoltaic (PV) systems, demonstrates a commitment to SDG 7 (Affordable and Clean Energy) and SDG 13 (Climate Action). The anaerobic sludge digestion process, generating 3300 m3 of methane gas, powers CHP engines that supply 25% of the plant’s electricity. The methane yield from the anaerobic digestion process was determined to be approximately 230 mL CH4/g VS. This yield reflects the efficient conversion of organic matter into biogas. Combined with the PV system, which provides 19% of the plant’s energy, the AWWTP achieves 44% energy self-sufficiency (Target 7.2). This significant reduction in grid reliance translates to a substantial decrease in greenhouse gas emissions (Target 13.2), mitigating the plant’s carbon footprint. The closed-loop system, transforming waste into energy, exemplifies a circular economy approach, minimizing environmental impact and enhancing operational sustainability. The project’s proactive stance on renewable energy integration serves as a compelling model for other wastewater treatment facilities, particularly in regions grappling with energy security and climate change.

3.3.4. SDG 8 and 11: Fostering Economic Growth and Sustainable Urban Development

The AWWTP upgrade has generated both direct and indirect employment opportunities, contributing to SDG 8 (Decent Work and Economic Growth). The enhanced water security and sanitation infrastructure have bolstered Aqaba’s attractiveness for investment, fostering sustainable urban development (SDG 11). The improved treated water network enhances the quality of life for residents by safeguarding public health and enhancing the city’s aesthetic appeal. The integration of green spaces and recreational areas, irrigated with reclaimed water, contributes to a more livable and resilient urban environment (Target 11.6).

3.3.5. SDG 14 and 15: Enhancing Biodiversity and Ecosystem Resilience

The AWWTP’s treated water storage ponds have transformed into thriving artificial wetlands, a vital ecological asset in a region experiencing wetland loss and water scarcity. This ecological haven has become a crucial stopover point for over 270 bird species, demonstrating the project’s contribution to SDG 14 (Life Below Water) and SDG 15 (Life on Land). The site’s recognition as a top 100 destination sustainability story [45] underscores its success in balancing environmental protection with economic development. Figure 5 shows an overview of the artificial wetland at the AWWTP and examples of bird species at the site.

3.3.6. SDG 17: Forging Strategic Partnerships for Sustainable Development

The success of the AWWTP upgrade is rooted in a robust multi-stakeholder partnership (Target 17.17), involving USAID, GIZ, the Jordanian government, and local authorities and companies. This collaborative approach, characterized by sharing expertise, financial resources, and technology, has been instrumental in building local capacity and ensuring the project’s long-term sustainability.

3.3.7. Beyond Direct Impacts: A Model for Integrated Development

The AWWTP upgrade serves as a powerful testament to the interconnectedness of the SDGs. Its multifaceted benefits, spanning water security, energy efficiency, climate action, economic growth, and ecosystem restoration, demonstrate the transformative potential of integrated resource management. Figure 6 shows the contribution of the plant upgrade project to specific SDGs, illustrating the project’s impact across environmental, social, and economic dimensions. This project provides a compelling model for other WWTPs in Jordan and beyond, particularly in regions facing similar challenges. By recognizing and leveraging the synergies between different SDGs, more comprehensive and lasting positive change can be unlocked, building a more sustainable and resilient future for all.

4. Conclusions

The demonstrable efficient performance of the CAS system over previous natural and extended activated sludge methods, evidenced by consistently high removal rates of pollutants and compliance with stringent reuse standards [30], underscores its efficiency in producing high-quality reclaimed water. The plant’s ability to provide 30% of Aqaba Governorate’s annual water budget is not merely a statistic; it represents a lifeline in a water-stressed environment, securing vital freshwater resources for future generations.
In addition, the plant upgrade is not an isolated achievement but a catalyst for a cascade of positive impacts across multiple SDGs. This project demonstrates the profound interconnectedness of environmental, economic, and social well-being. By seamlessly integrating renewable energy sources, the plant achieves 44% electrical self-sufficiency, significantly mitigating its carbon footprint and advancing SDG 7 and 13. Furthermore, the creation of thriving artificial wetlands has transformed a wastewater treatment facility into a biodiversity hotspot, attracting migratory birds and fostering eco-tourism, thus contributing to SDG 14 and 15. The project’s success in enhancing water reuse for agriculture and industry (SDG 6.4, 9.4), stimulating economic growth (SDG 8), strengthening urban sustainability (SDG 11), and fostering resource efficiency (SDG 12), underscores its holistic approach to sustainable development.
Furthermore, this project serves as a replicable blueprint for water-scarce regions worldwide. Its success is rooted in a collaborative framework, forged through robust multi-stakeholder partnerships (SDG 17), involving international and local expertise. This collaborative spirit has fostered knowledge transfer, built local capacity, and ensured the project’s long-term sustainability. The project’s ability to integrate advanced technologies with ecological restoration and economic diversification demonstrates the potential for WWTPs to become cornerstones of sustainable development.

Author Contributions

Conceptualization, L.A.A.-K.; Methodology, L.A.A.-K. and A.M.A.; Formal analysis, L.A.A.-K.; Resources, A.M.A.; Data curation, L.A.A.-K. and A.M.A.; Writing—original draft, L.A.A.-K. and A.M.A.; Writing—review and editing, L.A.A.-K. and A.M.A.; Visualization, L.A.A.-K. All authors have read and agreed to the published version of the manuscript.

Funding

This research received no external funding.

Data Availability Statement

Data are contained within the text. Further inquiries can be directed to the corresponding author.

Acknowledgments

The authors acknowledge the use of Zotero 6.0.36 and Quillbot v19.8.3.

Conflicts of Interest

Author Ahmad M. AlHanaktah was employed by the company Laboratories and Quality Department, Aqaba Water Company. The remaining author declares that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.

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Figure 1. Schematic diagram of Aqaba Conventional Activated Sludge Wastewater Treatment Plant.
Figure 1. Schematic diagram of Aqaba Conventional Activated Sludge Wastewater Treatment Plant.
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Figure 2. Physicochemical characteristics of effluent (a) and removal efficiency “R” (b) for the natural, extended activated sludge, and conventional activated sludge plants.
Figure 2. Physicochemical characteristics of effluent (a) and removal efficiency “R” (b) for the natural, extended activated sludge, and conventional activated sludge plants.
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Figure 3. Physicochemical characteristics of effluent for the natural, extended activated sludge, and conventional activated sludge plants.
Figure 3. Physicochemical characteristics of effluent for the natural, extended activated sludge, and conventional activated sludge plants.
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Figure 4. Reclaimed wastewater reuse quantities in irrigation and industry during 2022.
Figure 4. Reclaimed wastewater reuse quantities in irrigation and industry during 2022.
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Figure 5. (a) Overview of the constructed wetland at the Aqaba Wastewater Treatment Plant. (b,c) Bird species at the wetland. Photos are from Feras Rahahleh, and we have received permission from Feras Rahahleh to use them.
Figure 5. (a) Overview of the constructed wetland at the Aqaba Wastewater Treatment Plant. (b,c) Bird species at the wetland. Photos are from Feras Rahahleh, and we have received permission from Feras Rahahleh to use them.
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Figure 6. Contribution of the plant upgrade project to specific SDGs.
Figure 6. Contribution of the plant upgrade project to specific SDGs.
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Table 1. Physicochemical characteristics of influent and effluent and removal efficiency for the natural, extended activated sludge, and conventional activated sludge plants.
Table 1. Physicochemical characteristics of influent and effluent and removal efficiency for the natural, extended activated sludge, and conventional activated sludge plants.
Wastewater CharacteristicsNatural PlantExtended Activated Sludge PlantConventional Activated Sludge Plant
MeanStandard DeviationMinimum MaximumMeanStandard DeviationMinimum MaximumMeanStandard DeviationMinimum Maximum
BOD5 (mg/L)Influent347.354.6232.5435.0343.059.7203.0488.0408.5110.2192.0610.0
Effluent34.38.812.066.04.31.41.87.03.61.11.36.0
R (%)90.02.484.396.498.70.597.499.599.10.398.599.6
COD (mg/L)Influent853.1183.8600.01324.0852.8180.4456.01324.0738.4114.5528.01008.0
Effluent365.3114.528.0559.035.014.312.086.024.59.38.040.0
R (%)54.418.713.896.795.81.691.698.896.61.493.898.8
T.S.S (mg/L)Influent396.3139.2184.0847.0378.5130.0184.0847.0364.390.5215.0560.0
Effluent230.146.4110.0320.04.73.41.218.04.51.91.28.0
R (%)39.220.86.477.698.71.193.699.798.70.697.599.7
T-N (mg/L)Influent85.624.334.8133.080.929.95.4194.088.125.051.0146.0
Effluent62.828.91.5139.06.311.50.680.04.22.22.014.0
R (%)37.822.16.395.891.014.721.699.695.12.186.597.9
Table 2. Physicochemical and biological characteristics of effluent for the natural, extended activated sludge, and conventional activated sludge plants and the allowable concentration limits according to JS 893:2021 [30].
Table 2. Physicochemical and biological characteristics of effluent for the natural, extended activated sludge, and conventional activated sludge plants and the allowable concentration limits according to JS 893:2021 [30].
Wastewater CharacteristicsNatural PlantExtended Activated Sludge PlantConventional Activated Sludge PlantJS 893:2021 *
MeanStandard DeviationMeanStandard DeviationMeanStandard DeviationClass AClass BClass CClass D
BOD5 (mg/L)34.38.84.31.43.61.13010020015
COD (mg/L)365.3114.535.014.324.59.310020030050
T.S.S (mg/L)230.146.44.73.44.51.95010010015
T.D.S (mg/L)910.5198.5704.982.3734.0111.21500150015001500
Turb. (N.T.U)137.382.12.51.21.50.810--5
NO3 (mg/L)11.24.39.58.210.16.116161616
NH4 (mg/L)69.830.64.513.30.60.3____
T-N (mg/L)62.828.96.311.54.22.270707070
HCO3 (mg/L)317.459.7128.030.4125.118.1400400400400
PO4 (mg/L)NA NA 5.72.910101010
E. Coli (MPN/100 mL)24190124.8497.91.00.41001000-1.1
N.Eggs (Egg/L)Not Seen Not seen Not Seen 1111
pH8.00.37.30.37.10.3From 6 to 9From 6 to 9From 6 to 9From 6 to 9
* JS 893:2021 includes four water classes for irrigation application. Class A: for parking areas, playgrounds, and road verges within urban areas; Class B: for plenteous trees and green spaces and road verges outside cities; Class C: for field crops, industrial crops, and forestry; and Class D: for cut flowers. The permissible limits of Class D are the lowest among other categories and are considered the most stringent [30]
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Al-Khatib, L.A.; AlHanaktah, A.M. Wastewater Treatment Plant Upgrade and Its Interlinkages with the Sustainable Development Goals. Resources 2025, 14, 62. https://doi.org/10.3390/resources14040062

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Al-Khatib LA, AlHanaktah AM. Wastewater Treatment Plant Upgrade and Its Interlinkages with the Sustainable Development Goals. Resources. 2025; 14(4):62. https://doi.org/10.3390/resources14040062

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Al-Khatib, Laila A., and Ahmad M. AlHanaktah. 2025. "Wastewater Treatment Plant Upgrade and Its Interlinkages with the Sustainable Development Goals" Resources 14, no. 4: 62. https://doi.org/10.3390/resources14040062

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Al-Khatib, L. A., & AlHanaktah, A. M. (2025). Wastewater Treatment Plant Upgrade and Its Interlinkages with the Sustainable Development Goals. Resources, 14(4), 62. https://doi.org/10.3390/resources14040062

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