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Article

COVID-19 and Wastewater Management in Semi-Arid Regions: Observations and Global Comparisons from a GCC Country

by
Abdalrahman Alsulaili
1,*,
Fahad M. Al-Fadhli
2,
Hector A. Garcia
3,
Omar Ali
1 and
Nasser Alenezi
1
1
Civil Engineering Department, College of Engineering and Petroleum, Kuwait University, P.O. Box 5969, Kuwait City 13060, Kuwait
2
Chemical Engineering Department, Sabah Al Salem University City, Kuwait University, P.O. Box 5969, Safat 13060, Kuwait
3
Department of Water Supply, Sanitation and Environmental Engineering, IHE Delft Institute for Water Education, 2601 DA Delft, The Netherlands
*
Author to whom correspondence should be addressed.
Water 2025, 17(9), 1332; https://doi.org/10.3390/w17091332
Submission received: 17 March 2025 / Revised: 21 April 2025 / Accepted: 22 April 2025 / Published: 29 April 2025
(This article belongs to the Section Wastewater Treatment and Reuse)
Browse Figures
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Abstract

:
The COVID-19 pandemic has led to significant shifts in global water consumption, particularly affecting wastewater treatment plants (WWTPs). In Kuwait, where high residential water usage exists, the lockdowns resulting from the pandemic created a unique opportunity to evaluate the effects of altered human activity on wastewater characteristics. This study examines the effects of the lockdown on key wastewater parameters, including flow rate, COD, BOD, TSS, total Kjeldahl nitrogen (TKN), and total phosphorus (TP). Data were collected from four WWTPs in Kuwait over 4 to 8 years, with the Kabd WWTP providing continuous daily data for an 8-year period. A comparative analysis was conducted between pre-lockdown, lockdown, and post-lockdown periods using statistical methods such as paired t-tests. The study also integrates a global comparison to relate Kuwait’s findings. Results indicate a significant increase in wastewater flow (7.6%) during the lockdown, rising from 165,486 m3/d to 178,033 m3/d. COD and BOD levels increased by 27.1% and 18.9%, respectively, while TSS showed the largest rise at 29.9%. TKN increased by 20.1%, indicating higher nitrogenous waste contributions from residential sources. These findings highlight the pandemic’s impact on wastewater characteristics in Kuwait, driven primarily by increased domestic water consumption. The study underscores the necessity of adaptive wastewater management strategies, especially in semi-arid regions, where WWTPs must be equipped to handle unexpected changes in wastewater composition. This research provides essential insights for improving the flexibility of wastewater systems with future disruptions, contributing to both environmental management and public health awareness.

1. Introduction

The COVID-19 pandemic led governments worldwide to implement various public health measures to limit the spread of the virus [1,2]. These measures caused significant disruptions across multiple sectors, including manufacturing, energy, education, tourism, and aviation [3]. As a result, lockdown measures and lifestyle changes affected water and electricity consumption patterns, particularly in commercial and industrial sectors. In contrast, residential areas experienced increased consumption due to higher home occupancy rates during lockdowns [4,5].
This alteration in consumption patterns has also influenced the composition of wastewater, as the chemical makeup within municipal treatment systems can shift markedly based on varying contributions from industrial, commercial, and residential sources [6]. For example, components like phosphorus from household detergents may reflect the social and demographic characteristics of the residential catchment area [7]. Moreover, contaminant loads can vary considerably within the same city, depending on the level and type of industrial activity [8]. Sowby and Lunstad emphasize the importance of examining long-term disruptions in water infrastructure caused by pandemics, highlighting that such shifts in human behavior may persist beyond the immediate crisis [9]. These regulatory shifts, along with other factors, underscore the need for context-specific analyses to fully recognize the complex implications for environmental and public health policy. Moreover, analyzing changes in wastewater characteristics can clarify the broader environmental impacts of the pandemic, including the effects of reduced industrial activity and shifts in community behaviors [10].
Wastewater management is essential for protecting human health and the environment, especially in regions with limited water resources [11,12]. These shifts in wastewater characteristics also introduce significant operational challenges for wastewater treatment plants (WWTPs). Variations in the composition of wastewater, particularly from changes in domestic activity, can impact the performance of biological treatment processes. While WWTPs are designed to handle fluctuations, studies have shown that daily and seasonal variations in sewage quality influence nitrogen removal efficiency [13]. These variations, often linked to changes in flow rates, organic loads, and human activity patterns, may affect the stability of biological processes such as nitrification and denitrification. Higher organic loads and variations in chemical composition stress microbial communities within treatment facilities, potentially leading to operational issues such as odors, sludge bulking, and decreased overall performance [14]. In addition, shifts in the type and concentration of incoming wastewater can lead to inefficiencies, especially when the hydraulic load surpasses the system’s design capacity. This can result in environmental violations if untreated or partially treated wastewater bypasses the treatment process [15,16,17].
This study assesses the changes in wastewater characteristics, such as flow rates, chemical oxygen demand (COD), biochemical oxygen demand (BOD), total suspended solids (TSS), total Kjeldahl nitrogen (TKN), and total phosphorus (TP), during and after the lockdown periods in Kuwait. As we explore the broader context of global research on wastewater dynamics, a comprehensive review of the literature on similar studies conducted globally reveals a mix of findings. Some studies have reported improvements in water quality and reductions in pollution levels due to the lockdown measures, while others have observed more complex dynamics [18,19].
For instance, in urban areas of France, lockdown measures led to notable decreases in chemical oxygen demand and other pollutants due to reduced commercial activity, showcasing the direct relationship between human activity and environmental loadings [20]. Research from Australia demonstrated that mainly residential areas experienced an increase in wastewater parameters during the lockdown period. This observation was primarily attributed to increased domestic activities such as laundry, cooking, and sanitation, which collectively intensified wastewater volume and changed its characteristics. This study underscores the distinct impacts that residential zones can face under lockdown conditions, contrasting with mixed-use areas where industrial reductions might temper such changes [21]. These examples underline the variability in wastewater responses to COVID-19-related societal changes, influenced by local industrial and residential patterns.
While the focus in many regions has been on tracking the virus itself [22,23,24,25], there is a gap in studies examining the raw wastewater characteristics, especially in semi-arid regions like the Gulf Cooperation Council (GCC) countries. These regions, characterized by their unique climatic and socioeconomic conditions, face distinct challenges in water management [26], challenges that have been exacerbated by the pandemic.
Within this broader regional context, Kuwait serves as a typical example of GCC countries facing these shared constraints. While Kuwait exhibits some distinctive features including high per capita residential water usage and minimal industrial discharges [27,28], its overall climatic and infrastructure context aligns with many neighboring semi-arid nations. The high per capita water consumption of 447 L per day [29] in the residential sector, combined with Kuwait’s limited natural water resources and centralized wastewater treatment systems, can strain the capacity of treatment infrastructure. This necessitates adaptive strategies to handle increased wastewater volumes during disruptions [30]. Furthermore, the relatively low contribution of industrial effluents results in wastewater compositions that reflect primarily domestic sources, which may require different treatment approaches compared to regions with more diverse economic activity [31].
Accordingly, this study aims to investigate how COVID-19 lockdowns influenced key wastewater parameters in a semi-arid urban context, using Kuwait as a case study, and to compare these effects with global trends to draw regionally relevant insights for future wastewater management during public health crises. Furthermore, analyzing these findings and their implications can enhance our understanding of how public health crises affect water management in semi-arid areas, offering valuable data that can inform future environmental policies and strategies in similar contexts [18,19,32,33].
A detailed analysis of wastewater parameters from several treatment facilities in Kuwait was conducted, comparing the data across pre-lockdown, lockdown, and post-lockdown periods. This included a statistical examination to identify significant changes and trends. Additionally, the findings were compared with similar studies from other regions to provide a broader context of the pandemic’s impact on wastewater management. The comparative and statistical analysis improved the credibility of the conclusions and provided valuable insights into the regional differences in how wastewater systems responded to the COVID-19 pandemic.

2. Material and Methods

2.1. Selection of Study Area

The study is set in the context of the GCC countries, with Kuwait serving as a representative example due to its unique environmental and socioeconomic conditions. The GCC region, characterized by its arid climate and limited freshwater resources, faces significant challenges in water management [34]. Kuwait, like its neighboring countries, has a high per capita income and a rapidly growing population, which intensifies the demand on water resources and wastewater management systems [35].
Kuwait’s wastewater management system forms a critical component of the nation’s infrastructure, designed to support the country’s urban and demographic growth. With comprehensive sanitation facilities reaching approximately 90% of the population, Kuwait has made substantial progress in public health and environmental governance [36]. Approximately 75% of the total wastewater is treated to stringent standards, often meeting the criteria for reverse osmosis quality. This reclaimed water is then employed across various applications, notably in the agricultural sector, where it contributes to about 19% of the total water usage [37]. The ongoing advancements in Kuwait’s wastewater treatment infrastructure are essential for adapting to the increasing pressures from urban growth and climate variability, ensuring the resilience of water management systems in the GCC’s challenging environmental context.

2.2. Study Design and Setting

This study investigates the effects of the COVID-19 lockdown on wastewater characteristics, with a focus on evaluating changes in wastewater quality and management within Kuwait, a region known for its arid climate and high residential water usage. Table 1 shows the different lockdown measures during the pandemic, including changes in curfew times and restrictions.
The COVID-19 lockdown measures in Kuwait lasted from March to June 2020, with varying levels of restrictions. In this study, the analysis focuses on March through May, as May represented the period of full curfew, during which significant changes in wastewater generation were expected. March and April were included to capture the transition leading to full lockdown. However, June was excluded from the analysis because restrictions were eased to nighttime-only curfews, with normal daytime activities resuming. Therefore, our graphical representations and statistical analyses concentrate on the March-May period to reflect the most relevant changes.
The study’s geographic scope centers around Kuwait’s wastewater management infrastructure, particularly the Kabd Wastewater Treatment Plant and three smaller facilities: Wafra, Sabah Al-Ahmed Sea City, and New Khiran. The Kabd plant, situated 40 km west of Kuwait City and serving the Al-Jahra governorate, is of strategic importance due to its substantial capacity. Approximately 400,000 residents are served by this facility, which is designed to manage an average daily flow of 180,000 cubic meters, with the capacity to accommodate up to 270,000 cubic meters during peak conditions [38]. Notably, the Kabd plant is equipped with advanced, fully computer-controlled operations via a Distributed Control System, and it primarily processes domestic wastewater under conditions of high temperatures and low rainfall.
In contrast, the three smaller plants (Wafra, Sabah Al-Ahmed Sea City, and New Khiran) collectively treat a total capacity of 30,000 cubic meters per day. These facilities, also focused on treating domestic wastewater, provide a comparative perspective within the same national framework, allowing the study to examine both large-scale and smaller-scale impacts of the lockdown on wastewater management across various community sizes and operational capacities.

2.3. Data Collection and Time Frame

Data collection for this study focused on key wastewater parameters (COD, BOD, TSS, TKN, and TP), which were consistently monitored across different treatment plants. However, the frequency of data collection varied between facilities.
Data were sourced from the Ministry of Public Works (MPW), which maintains direct oversight of wastewater treatment facilities throughout Kuwait. To provide a detailed longitudinal perspective, data collection spanned several years across different facilities, as outlined in Table 2. At Kabd WWTP, a single grab sample was collected each day during normal operation, allowing for a high-resolution analysis of short-term trends, including potential disruptions during the COVID-19 lockdown. In contrast, the three smaller plants (Wafra, Sabah Al-Ahmed Sea City, and New Khiran) had only monthly data, which limited their ability to capture short-term fluctuations. Due to this difference in data resolution, only Kabd was included in the main statistical analysis and trend evaluation, while the data from the other plants were presented in the Appendix A.
Standard methods used for each parameter were systematically applied to ensure consistent and reliable data collection. Table 3 lists the sampling methods and the associated wastewater parameters collected, underscoring the standardized approach adopted for this study. Each parameter’s collection method is described, ensuring adherence to recognized analytical standards. The careful and thorough approach to data collection and validation supports the credibility of the findings, providing a reliable basis for further analysis and discussion on how the pandemic affected wastewater management practices in Kuwait.

2.4. Data Processing and Analysis

Data processing in this study involved the conversion of raw data into a format suitable for detailed analysis. Daily measurements were aggregated into monthly averages to facilitate the comparison of data across the same months in different years. This aggregation was essential for reducing day-to-day fluctuations, thereby highlighting broader trends and shifts attributable to the COVID-19 lockdown, allowing for a clearer understanding of how wastewater characteristics evolved over the study period.
The initial phase of data analysis involved the graphical representation of monthly averages for each wastewater parameter from the facilities across Kuwait. These visualizations were instrumental in identifying significant changes or anomalies that occurred during the lockdown periods compared to the regular operational phases. By plotting these values with particular emphasis on the lockdown period in 2020, temporal patterns of impact across multiple years were exposed.
In the analysis, wastewater characteristics were first examined in terms of concentration (mg/L). Subsequently, for the Kabd facility, the loads were calculated from the concentration data to provide a more accurate representation of the total quantities of pollutants processed daily. This conversion was essential for assessing the true scale of changes in wastewater quality during the lockdown periods.
Statistical tests, specifically paired t-tests, were then applied only to the Kabd dataset, as it was the only plant with daily measurements, to compare the means of wastewater characteristics during April–May 2020 were compared. The same months in non-lockdown years (2016–2019, 2021–2023). This statistical method was selected due to its ability in comparing paired samples where each set of data is naturally related, such as the same months across different years. This approach controlled for inherent variability in wastewater characteristics typical of different periods. The results of these analyses were examined to determine the statistical significance of observed changes.

2.5. Comparative Analysis

In the comparative analysis, regions were selected based on varying factors such as population density, urbanization levels, and catchment area characteristics, alongside the availability of relevant studies. This approach facilitated the inclusion of regions that could offer diverse perspectives yet had sufficient data comparability with Kuwait. The focus was on ensuring that the regions chosen provided a broad yet detailed view necessary for a comprehensive comparative evaluation.
For the comparison, the same wastewater parameters measured in Kuwait (Flow rate, COD, BOD, TSS, TKN, and TP) were prioritized as they are commonly reported in other regions and are pivotal for assessing wastewater quality and environmental impacts. Data from several countries, including Australia, France, Greece, China, and Iran, were integrated, where studies provided insights into multiple settings within these countries when available. This strategy allowed for an analysis that considers different urban and residential dynamics, maintaining the methodological focus for subsequent detailed analysis.

3. Results and Discussion

3.1. Trend Analysis of Wastewater Parameters at Kabd Plant

The investigation into the trends of wastewater characteristics at the Kabd treatment plant encompassed an analysis of six key parameters: flow, COD, BOD, TSS, TKN, and TP. For each parameter except flow, two distinct graphical representations were prepared, depicting both concentration in milligrams per liter (mg/L) and load in kilograms per day (kg/d). This dual-presentation format in Figure 1 provides a comprehensive view of the changes over the study period from 2016 to 2023.
The trend graphs for flow, illustrated only by its volumetric measure (m3/day), reveal fluctuating levels with notable peaks and troughs corresponding to seasonal variations and specific wastewater management activities. This variability is particularly marked during the COVID-19 lockdown periods, where changes in residential water use are expected. For the other parameters (COD, BOD, TSS, and TKN), the concentration graphs typically show significant fluctuations corresponding with the load graphs. However, TP stands out as an exception, as the graphical visualization indicates no notable increase or decrease during the lockdown period, unlike other parameters that exhibited clear trends. This suggests that the primary sources of phosphorus in wastewater remained relatively stable throughout the lockdown.
The significance of these observed trends was further validated through rigorous statistical testing, the details and outcomes of which will be discussed in subsequent sections. Moreover, additional graphs for the smaller plants (Wafra, Sabah Al-Ahmed Sea City, and New Khiran) are included in the Appendix A. Noteworthy is the absence of significant trends in these smaller facilities, which might be attributed to their reduced capacities and the distinct characteristics of their respective catchments. These differences could be influencing the impact of lockdown measures on wastewater parameters compared to the more substantial changes observed at the Kabd facility.

3.2. Statistical Analysis of Wastewater Fluctuations During the COVID-19 Lockdown

The analysis of wastewater properties during the COVID-19 lockdown in Kuwait demonstrates substantial changes across numerous parameters, which are statistically corroborated through comparative evaluation with non-lockdown periods. The discussion below examines changes in each parameter during the lockdown, as detailed in Table 4. The table presents average values, percentage changes, and p-values, illustrating the statistical significance of these findings.
The statistical analysis primarily focuses on load (kg/day) rather than concentration (mg/L) to ensure accurate trend identification. Since flow rates increased significantly during the lockdown, relying solely on concentration values could be misleading, as higher flow volumes may dilute pollutant concentrations despite an actual increase in pollutant mass. This is particularly evident in BOD, where the load graph clearly indicates an increase, whereas the concentration graph does not fully capture this trend. By prioritizing load-based analysis, the study accounts for variations in flow rates and provides a clearer picture of changes in wastewater composition.
The wastewater flow rates at the Kabd treatment plant exhibited a statistically significant increase during the COVID-19 lockdown period. The comparison was conducted between the average flowrates recorded during the lockdown months (April–May 2020) and the corresponding months in non-lockdown years (2016–2019, 2021–2023). The average flow increased from 165,486 m3/d in non-lockdown years to 178,033 m3/d in 2020, marking a 7.6% rise. The t-statistic of −13.45 and a p-value of <0.001. This observed increase in wastewater flow is primarily attributed to heightened domestic water usage as the COVID-19 restrictions forced populations to remain indoors for extended periods [39]. Similar increases in wastewater flow have been reported in numerous regions across the globe, including Australia, China, Iran, Germany, Italy, and the United States, where lockdowns led to elevated domestic wastewater generation due to changes in human activities and residential water use behaviors during the pandemic [10,21,40,41,42,43,44].
TSS levels at the Kabd treatment plant exhibited a statistically significant increase during the COVID-19 lockdown period. The average TSS load rose from 29,040 kg/d in the non-lockdown period to 37,728 kg/d, marking a substantial 29.9% increase with a t-statistic of −13.05 and a p-value of <0.001. This observed rise in TSS levels reflects the heightened domestic activities and wastewater contributions during the lockdown, likely stemming from increased cleaning, cooking, and overall residential water usage as populations were restricted to their homes for extended durations [45]. Similar trends have been reported in studies conducted in other regions, such as Australia, where researchers like [21] have observed increased domestic wastewater outputs during lockdowns. The increase in TSS levels observed in the current study aligns with these findings, underscoring the significant impact of changing human activities and behaviors on wastewater characteristics during global health crises like the COVID-19 pandemic.
The Chemical Oxygen Demand also exhibited a statistically significant increase. COD escalated by 27.1% from 100,415 kg/d to 127,663 kg/d, with a t-statistic of −22.08 and a p-value of <0.001. This change, supported by statistical evidence, indicates a higher organic load during the lockdown, likely from increased food waste and hygiene activities at home [46]. This pattern differs from the trends observed in regions like Greece, where lockdowns led to a decrease in BOD due to the reduction in industrial activities and changes in population mobility [47]. In contrast, the significant increase in COD observed in this study suggests that the impact of the COVID-19 lockdown on wastewater characteristics in Kuwait was primarily driven by the changes in residential activities and domestic water usage, rather than the reduction in industrial discharges.
On the other hand, BOD increased by 18.9% at the Kabd treatment plant, rising from 52,020 kg/d to 61,825 kg/d, supported by a t-statistic of −18.33 and a p-value of <0.001. This increase in BOD often correlates with elevated organic material in the wastewater, a direct result of more people staying indoors and generating organic waste during the lockdown. The findings differ from some studies conducted in other regions, such as France, where lockdowns led to mixed impacts on BOD; some areas experienced decreases, while others showed no significant changes, depending on the specific local conditions and changes in residential water use and domestic activities during the lockdown period [20].
However, TKN exhibited a statistically significant increase of 20.1%, rising from 9279 kg/d to 11,147 kg/d, with a t-statistic of −4.44 and a p-value of <0.001. While TKN levels showed peaks in certain years, these fluctuations are likely due to localized plant operations or external factors. Studies have shown that the composition of nitrogen compounds in domestic wastewater inflow varies with seasons, weather, and resident activities [48], further supporting that these variations are not necessarily anomalies but rather expected changes influenced by multiple environmental and operational factors. However, when analyzed across multiple years, the lockdown period consistently demonstrated a significant increase in TKN, reinforcing a broader trend rather than isolated annual variations. This notable rise in TKN levels during the COVID-19 lockdown period can be attributed to the elevated discharge of protein-rich waste and other nitrogenous substances from residential sources [49]. This finding contrasts with studies conducted in regions such as China, where lockdowns did not significantly impact nitrogen levels in wastewater, suggesting that the observed increase in TKN in this study may be linked to a higher reliance on home-based food preparation and potentially different dietary habits among the local population during the lockdown restrictions [40].
In contrast, phosphate levels showed no statistically significant change, with a minimal percentage variation of 0.6% and a p-value of 0.491. This stability in phosphate concentrations might indicate that the primary sources of phosphates, such as detergents and soaps, remained relatively constant during the lockdown period, or that any changes in residential use were offset by reductions in commercial and industrial discharges [50]. Phosphorus in domestic wastewater primarily originates from food waste, human excreta, detergents, and phosphate dosing in tap water, with laundry detergents alone contributing approximately 14% of the total domestic phosphorus load [51]. This suggests that laundry remains predominantly an at-home activity, with phosphate loads remaining stable even during lockdown periods, as domestic laundry patterns did not change significantly despite variations in other wastewater parameters. This stability in phosphate levels stands in contrast with findings from areas that experienced more substantial industrial reductions, which resulted in altered phosphate outputs in their wastewater streams [20]. This observation is also consistent with Kuwait’s limited industrial base, where wastewater inflow is largely residential in origin. Unlike in mixed-use or industrialized catchments, the absence of significant industrial phosphorus discharges in Kuwait likely contributed to the minimal variation observed in TP concentrations during the lockdown period. Therefore, the relatively uniform phosphorus inputs from households may have buffered any pandemic-related disruptions, explaining the observed stability.

3.3. Comparative Analysis with Global Data

The comparative examination of wastewater properties during the COVID-19 lockdown across diverse global regions illuminates the varied impacts influenced by factors including population density, urbanization, and catchment area. The insights gained from these comparative findings, as detailed in Table 5, can inform more effective and adaptive policymaking to mitigate the environmental impacts of future global crises, accounting for the nuanced ways in which local communities and infrastructure systems respond to unprecedented disruptions.
In Australia, distinct differences were noted between two types of catchment areas. In mixed residential, commercial, and industrial areas (Australia 1), there was a significant decrease in COD, which can be attributed to the substantial reduction in industrial activities during the lockdown. Conversely, in primarily residential areas (Australia 2), increases in COD and BOD by 2% to 40% were observed, likely due to heightened domestic water usage as residents stayed home during the lockdown [21].
In another region, France exhibited a similar pattern where different urban setups responded uniquely. In France 1, where the catchment type is mixed residential, commercial, and industrial, BOD decreased by 40%, reflecting reduced commercial activities and lower graywater production from industries like catering and hairdressing. However, France 2, with primarily residential settings, showed no significant change in wastewater characteristics, suggesting that the smaller scale of industrial and commercial activities had a minimal impact on wastewater parameters during the lockdown [20]. Greece, with a mixed residential and commercial catchment, demonstrated reductions across various parameters including COD, BOD, and TKN, due to the decrease in commercial activity and consistent ammonium loads [47].
Conversely, in China and Iran, where the catchment types are variable, there was an overall increase in flow and a decrease in COD and BOD. These changes were largely due to increased domestic water consumption for sanitation and personal hygiene, coupled with reduced industrial discharge which led to the dilution of pollutants [10,40].
Kuwait’s scenario, mainly residential with a high population, showed an increase in almost all wastewater parameters, with COD and BOD rising by 27% and 19%, respectively. This increase is indicative of heightened domestic water usage, which contrasts with regions where significant reductions in industrial activities typically led to lower wastewater contaminant loads.
Comparative analysis across different regions, as shown in Table 5, indicates that variations in catchment types and the mix of residential versus industrial characteristics significantly influence wastewater responses during lockdowns. In primarily residential areas, increases in wastewater parameters such as flow, COD, BOD, and TSS are typically observed, attributed to heightened domestic activities from residents staying at home. In contrast, mixed-use areas with industrial and residential sectors often experience decreases in these parameters during lockdowns due to reduced industrial operations, which diminish the amount of industrial discharge into the wastewater systems.
Moreover, the impact of industrial activity reduction during lockdowns is pronounced in mixed zones, where the scaling down of industrial operations leads to a significant decrease in pollutants typically associated with industrial processes, notably observed in COD and TSS levels. Additionally, areas with high population densities show more marked changes in wastewater parameters during lockdowns compared to less densely populated areas, highlighting the significant role of local infrastructure and regulatory frameworks in managing environmental impacts during global disruptions.

3.4. Implications and Future Research Directions

The study’s findings provide important insights into wastewater management in semi-arid regions like Kuwait, particularly under conditions similar to those observed during the COVID-19 lockdown. It highlights the need for flexible management approaches that can adjust to sudden increases in domestic wastewater, which are essential for maintaining environmental health standards during public health crises. While wastewater treatment plants regularly handle seasonal changes in wastewater characteristics—such as shifts in water use due to temperature variations or population movement during holidays—the COVID-19 lockdown presented a rapid and unexpected change in influent composition. Unlike predictable seasonal trends, the lockdown caused an immediate increase in wastewater loads due to simultaneous changes in human activity, requiring adjustments without prior planning. This emphasizes the importance of preparedness in wastewater treatment facilities, ensuring they can adapt to unusual disruptions beyond typical annual variations.
In this context, policy frameworks tailored to semi-arid settings should focus on building operational flexibility through real-time monitoring systems and modular treatment units that can scale based on demand. Investments in early warning systems for influent composition changes, combined with adaptive operation protocols, could improve plant resilience. Moreover, integrating decentralized treatment units in high-density residential zones may reduce pressure on centralized facilities during demand surges.
To strengthen the resilience of wastewater management systems, further research should explore long-term effects of pandemic responses on wastewater infrastructure and investigate advanced treatment technologies that can enhance adaptability during unpredictable events. Future studies could analyze how lasting shifts in human activities impact wastewater characteristics in semi-arid regions, offering guidance for infrastructure planning. Additionally, evaluating innovative wastewater treatment solutions that help stabilize operations during fluctuating demand periods, such as lockdowns, could support more efficient and sustainable management practices. These efforts will contribute to ensuring wastewater treatment systems remain effective, adaptable, and environmentally sustainable, even in the face of global public health challenges.

4. Conclusions

This study systematically analyzed the impact of COVID-19 lockdown measures on wastewater characteristics, focusing on variations in key parameters due to shifts in domestic and commercial water usage. The findings indicate that increased residential water consumption during lockdowns led to significant rises in flow, organic matter, suspended solids, and nitrogen levels, whereas phosphorus levels remained stable. These results show how human activity influences wastewater composition and highlight the importance of considering behavioral and socioeconomic factors in wastewater management.
Beyond Kuwait, the comparison with global datasets showed that the effects of lockdowns varied across regions depending on catchment type, regulations, and population size. While residential areas generally saw an increase in wastewater loads, mixed-use areas with significant industrial activity often had lower levels due to reduced commercial operations. These differences emphasize the need for region-specific wastewater monitoring approaches rather than general models that do not reflect local conditions.
By addressing these gaps, this research provides a clearer understanding of wastewater changes during major disruptions. The findings can support future planning, policy-making, and public health strategies, ensuring wastewater systems can adapt to sudden changes. Further research is needed to examine the long-term effects of such events on wastewater treatment performance, energy demand, and new pollutants, helping to improve wastewater management in a changing world.

Author Contributions

A.A.: Conceptualization, supervision, investigation, methodology, project administration, writing—original draft. F.M.A.-F.: Conceptualization, methodology, and writing—review and editing. H.A.G.: Conceptualization, methodology, and writing—review and editing. O.A.: Formal analysis, data curation, methodology, software, validation, visualization, writing—original draft. N.A.: Data curation, formal analysis, methodology, software. All authors have read and agreed to the published version of the manuscript.

Funding

This research was funded by Kuwait University, grant number RE 04/21.

Data Availability Statement

The data presented in this study are available on request from the corresponding author due to legal reasons.

Acknowledgments

The authors would like to thank the Ministry of Public Works and the Kabd Wastewater Treatment Plant for their cooperation in providing data related to wastewater treatment. Additional thanks are extended to the Research Sector at Kuwait University for their financial support of this project, funded under project code: RE 04/21.

Conflicts of Interest

The authors declare no conflicts of interest.

Appendix A

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Figure A1. Trend Analysis for Smaller Treatment Plants: Wafra. This figure presents the monthly averages for wastewater parameters such as TSS, COD, BOD, INF_TKN, and INF_TOTAL_PO4 across the years 2018–2022.
Figure A1. Trend Analysis for Smaller Treatment Plants: Wafra. This figure presents the monthly averages for wastewater parameters such as TSS, COD, BOD, INF_TKN, and INF_TOTAL_PO4 across the years 2018–2022.
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Figure A2. Trend Analysis for Smaller Treatment Plants: Sabah Al-Ahmed Sea City. This figure presents the monthly averages for wastewater parameters such as TSS, COD, BOD, INF_TKN, and INF_TOTAL_PO4 across the years 2018–2022.
Figure A2. Trend Analysis for Smaller Treatment Plants: Sabah Al-Ahmed Sea City. This figure presents the monthly averages for wastewater parameters such as TSS, COD, BOD, INF_TKN, and INF_TOTAL_PO4 across the years 2018–2022.
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Figure A3. Trend Analysis for Smaller Treatment Plants: New Khiran. This figure presents the monthly averages for wastewater parameters such as TSS, COD, BOD, INF_TKN, and INF_TOTAL_PO4 across the years 2018–2022.
Figure A3. Trend Analysis for Smaller Treatment Plants: New Khiran. This figure presents the monthly averages for wastewater parameters such as TSS, COD, BOD, INF_TKN, and INF_TOTAL_PO4 across the years 2018–2022.
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Water 17 01332 g001aWater 17 01332 g001b
Figure 1. Wastewater flowrate, monthly concentration (left), and load (right) averages for TSS, COD, BOD, TKN, and TP at Kabd WWTP. The black line represents the multi-year average (2016–2019, 2021–2022) with a gray shaded range (Std Dev). The red line highlights 2020, marking the lockdown period (April–May). Months are numbered 1–12 (January–December).
Figure 1. Wastewater flowrate, monthly concentration (left), and load (right) averages for TSS, COD, BOD, TKN, and TP at Kabd WWTP. The black line represents the multi-year average (2016–2019, 2021–2022) with a gray shaded range (Std Dev). The red line highlights 2020, marking the lockdown period (April–May). Months are numbered 1–12 (January–December).
Water 17 01332 g001aWater 17 01332 g001b
Table 1. Lockdown periods in Kuwait during COVID-19.
Table 1. Lockdown periods in Kuwait during COVID-19.
DateMeasure DetailsDuration
22-MarPartial curfew imposed from 5 PM to 4 AM.11 h
6-AprExtended partial curfew by 2 h, from 5 PM to 6 AM.13 h
23-AprDuring Ramadan, extended partial curfew from 4 PM to 8 AM.16 h
10-MayFull curfew imposed, lasting until 30 May.24 h
31-MayReturned to partial curfew from 6 PM to 6 AM.12 h
21-JunAdjusted partial curfew from 7 PM to 5 AM.10 h
Table 2. Timeframe of Data Collection Across Treatment Facilities.
Table 2. Timeframe of Data Collection Across Treatment Facilities.
PlantYears of Data CollectionData Type
Kabd WWTP2016–2023Daily
Wafra2018–2022Monthly
Sabah Al-Ahmed Sea City2018–2022Monthly
New Khiran2019–2022Monthly
Table 3. Sampling Methods for Selected Wastewater Parameters.
Table 3. Sampling Methods for Selected Wastewater Parameters.
ParameterStandard MethodTechnique Used
TSSAPHA 2540 DGravimetry
CODAPHA 5220 DColorimetric Method
BODAPHA 5210 B5-day BOD Test (Manual)
T-KNAPHA 4500-Norg BKjeldahl Method
T-PO4APHA 4500-P EColorimetric Method
Table 4. Statistical Analysis of Wastewater Parameters During Non-Lockdown vs. Lockdown Periods.
Table 4. Statistical Analysis of Wastewater Parameters During Non-Lockdown vs. Lockdown Periods.
ParameterUnitsNon-Lockdown Lockdown Percentage Change (%)t-Statisticp-Value
Flow(m3/d)165,486 178,0337.6−13.45<0.001
TSS(kg/d)29,04037,72829.9−13.05<0.001
COD(kg/d)100,415127,66327.1−22.08<0.001
BOD(kg/d)52,02061,82518.9−18.33<0.001
TKN(kg/d)927911,14720.1−4.44<0.001
PO4(kg/d)329233110.6−0.70.491
Table 5. Comparative Analysis of Wastewater Parameter Changes During COVID-19 Lockdown Across Different Regions.
Table 5. Comparative Analysis of Wastewater Parameter Changes During COVID-19 Lockdown Across Different Regions.
CountryAustraliaFranceGreeceChinaIranKuwait
Australia 1
Sydney		Australia 2
Smaller Towns		France 1
Paris		France 2
City of Nice
Catchment TypeMixed Residential, Commercial, IndustrialPrimarily ResidentialMixed Residential, Commercial, IndustrialPrimarily residential.Mixed Residential, Commercial, IndustrialMixed Residential, Commercial, IndustrialMixed Residential and CommercialPrimarily Residential
Population/ParametersHigh Population (>100,000)Low Population (<30,000)Between 250 k and 300 k
110 k daily inward commuters		Between 250 k and 300 k
53 k daily inward commuters		Between 3 M and 4 MVariableVariableHigh Population (>400,000)
Flow↓ 36.5%↑ 28.6%No significant changeNo significant changeNo significant change↑↑ 20%↑ 8%
COD↓ 47%↑ 19%↓ 45%↓↓↓ 23%↑ 27%
BOD↓ 7–61%↑ 2–40%↓ 40%↓↓↓ 16%↑ 19%
TSS↓ 35–45%No significant change↓ 35%↓↓No significant change↑ 30%
TKN↓ 38%↑ 14%↓ 30%↓↓n.d↑ 20%
TP↓ 9–50%↑ 19–22%↓ 25%↓↓n.dNo significant change
Reference[21][20][47][40][10]*
Note: * Data derived from the present study.
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Alsulaili, A.; Al-Fadhli, F.M.; Garcia, H.A.; Ali, O.; Alenezi, N. COVID-19 and Wastewater Management in Semi-Arid Regions: Observations and Global Comparisons from a GCC Country. Water 2025, 17, 1332. https://doi.org/10.3390/w17091332

AMA Style

Alsulaili A, Al-Fadhli FM, Garcia HA, Ali O, Alenezi N. COVID-19 and Wastewater Management in Semi-Arid Regions: Observations and Global Comparisons from a GCC Country. Water. 2025; 17(9):1332. https://doi.org/10.3390/w17091332

Chicago/Turabian Style

Alsulaili, Abdalrahman, Fahad M. Al-Fadhli, Hector A. Garcia, Omar Ali, and Nasser Alenezi. 2025. "COVID-19 and Wastewater Management in Semi-Arid Regions: Observations and Global Comparisons from a GCC Country" Water 17, no. 9: 1332. https://doi.org/10.3390/w17091332

APA Style

Alsulaili, A., Al-Fadhli, F. M., Garcia, H. A., Ali, O., & Alenezi, N. (2025). COVID-19 and Wastewater Management in Semi-Arid Regions: Observations and Global Comparisons from a GCC Country. Water, 17(9), 1332. https://doi.org/10.3390/w17091332

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