Husnain Haider

Solar stills provide a simple, sustainable method for producing freshwater in arid, coastal, and remote regions where conventional desalination is often impractical. This study experimentally evaluated a tubular solar still fabricated from locally available materials under controlled indoor conditions. The thermal performance and freshwater productivity were analyzed with respect to ambient air temperature (Ta), humid air temperature (Tha), cover temperature (Tc), trough temperature (Tt), water temperature (Tw), relative humidity, artificial solar radiation intensity (Sr), and associated temperature differentials. Pearson correlation, linear regression, and principal component analysis (PCA) were employed to investigate the relationships among the measured variables. Water and trough temperatures increased rapidly and reached steady-state values of approximately 46 °C after 2 h, whereas the maximum freshwater yield reached 14.3 g/h. Freshwater yield exhibited strong positive linear relationships with the principal thermal driving forces, including Tw − Ta (R² = 0.996), Tw − Tc (R² = 0.989), Tha − Ta (R² = 0.980), and Tha − Tc (R² = 0.940), while showing a strong inverse relationship with the relative humidity difference (RHha − RHa; R² = 0.964). The high thermal efficiency (about 75% prior to accounting for salinity effects) achieved under steady-state conditions proves that precise irradiance control minimizes heat loss. Pearson correlation analysis confirmed significant positive correlations between freshwater yield and the thermal variables (r = 0.957–0.998, p < 0.01) and significant negative correlations with the relative humidity parameters (r = −0.761 to −0.951, p < 0.01). PCA showed that the first principal component explained 83.55% of the total variance, representing the dominant thermal behavior of the system, while the first four principal components together accounted for 98.47% of the dataset variability. These findings demonstrate that freshwater productivity is primarily governed by internal thermal gradients rather than radiation intensity alone and highlight the importance of optimizing heat and mass transfer processes to improve the performance of low-cost tubular solar stills for sustainable desalination applications. These findings provide useful insight for the optimization and scale-up of tubular solar still systems for sustainable desalination applications in water-scarce regions, providing a sustainable framework to produce low-cost potable water from seawater via renewable solar energy.

Efficient storm drainage systems (SDSs) play a pivotal role in sustainable urban development. In arid regions, urban SDS often underperform during prolonged dry periods, leaving them inoperable due to sediment buildup and clogging from the intrusion of sprawling waste. Municipalities either rely on emergency response to flooding complaints or inspect storm sewers individually to handle flash floods and conserve high-value rainwater. The present study developed a risk-based decision-analysis framework for resource-efficient inspection and maintenance (I&M) planning of SDS to prioritize geographically clustered sub-zones. The study applied the framework to a case study of three urban zones with varying population densities and land use distributions in Buraydah, Qassim, Saudi Arabia. The framework integrates fuzzy synthetic evaluation (FSE) to address data limitations and subjective expert knowledge, with geographic information system (GIS)-based spatial analysis to assess three risk factors: likelihood, consequences, and detectability of sewer clogging potential. In addition to traditional likelihood-based evaluation of the susceptibility of smaller sewers to sediment accumulation due to performance anomalies, the consequence analysis augmented the process by considering land-use characteristics, exemplified by commercial areas exhibiting higher socio-economic losses than open spaces that buffer excess runoff. The detectability factor consolidated the decision analysis by incorporating the impacts of past delayed inspections, deep manholes, and scattered construction-related waste on clogging potential. The analysis identified sub-zones with aged sewers, deep manholes, long-awaited inspections, and high population densities, resulting in a high risk. GIS maps showing distinct impacts of the three factors on overall flood risk facilitate municipalities facing unique urban flooding challenges arising from sediment accumulation during long dry periods, followed by short-duration, high-intensity rainfall.

In the Kingdom of Saudi Arabia (KSA) and other arid regions, higher education institutions account for a significant share of energy consumption and greenhouse gas (GHG) emissions. Improving the environmental performance of higher education institutions is important to achieving nationwide impact reduction. This study evaluates the water, energy, and carbon (WEC) footprint of higher education campuses in arid environments. Qassim University (QU), KSA, is a leading public institution of higher education and research in Buraydah City and was selected for this study. A comprehensive assessment based on the GHG Protocol was conducted for the period 2022–2025, covering Scope I, II, and III emissions. This study analyzed institutional data on water use, wastewater, electricity consumption, transportation, waste generation, and air travel. The results show that total water consumption increased from 354,747 m³ in 2022 to 547,268 m³ in 2025, with per capita use rising from 46.2 to 61.7 L/c/day. Net water demand, including irrigation, reached 877,456 m³ in 2025. The declining trend in energy consumption between 2022 and 2025 reflects significant (33%) energy savings with the use of sensors and the overall tendency towards sustainability. Correspondingly, Scope II emissions decreased significantly from 147.2 million kg CO₂/year to 99.1 million kg CO₂/year and were the dominant CO₂ contributor (60–75% of total emissions). In contrast, Scope III emissions from commuting staff and students increased, with transport-related emissions rising from 36.4 million kg CO₂/year in 2022 to 52.2 million kg CO₂/year in 2025. This study also evaluated current and potential CO₂ emission reduction scenarios targeting energy and transportation systems on the QU campus. The findings indicate that the deployment of a 5.1 MW solar energy system can generate approximately 8.6 million kWh annually, resulting in a reduction of around 4000 tCO₂ and contributing to nearly 43% of the 2030 emission reduction target. In addition, transportation-focused strategies—including modal shift, vehicle electrification, and hybrid learning approaches—demonstrate significant mitigation potential, with total reductions reaching up to 18,700 tCO₂ by 2030. Overall, this study contributes to the limited body of knowledge on WEC footprint assessments on university campuses in arid regions and provides a baseline for future sustainability planning.

Small communities in the Kingdom of Saudi Arabia (KSA) without a sewerage system commonly rely on septic tanks and long-distance transport of wastewater to the nearest centralized treatment facilities, resulting in high operational costs, social nuisance, and limited opportunities for treated effluent reuse. For a small community of 1300 persons in Al Qaraa (Qassim, KSA), this study performs life cycle analysis (LCA) to evaluate the environmental sustainability of a low-cost membrane bioreactor (LC-MBR)-type for decentralized on-site treatment as an alternative to wastewater transportation to a conventional extended aeration activated sludge process (EA-ASP)-type centralized system operating in the nearest larger city of Al-Bukayriyah. SimaPro^® 8.3.0.0 with the ecoinvent 3.0 database and ReCiPe 16 midpoint methodology shows that the decentralized LC-MBR scenario outperformed the centralized option with a 49 km-long wastewater transportation route in 13 out of 15 selected midpoint categories when considering relative and normalized impacts. In the EA-ASP, primary treatment dominated environmental impacts across most categories, driven by high energy demand for wastewater pumping, whereas freshwater and marine eutrophication were primarily influenced by treatment efficiency. With smaller normalized values, secondary treatment had a greater relative impact on urban and agricultural land occupation categories, attributed to the use of clay and rice bran in low-cost membrane fabrication in an LC-MBR. Tertiary treatment in the LC-MBR scenario, incorporating coagulation and granular activated carbon, significantly reduced freshwater eutrophication. Although normalized endpoint impacts indicated comparable ecosystem impacts for both systems, the LC-MBR resulted in 8% lower impacts on human health and 60% lower on resource depletion. Overall, the findings support decentralized wastewater treatment as a sustainable solution for small communities in arid regions and provide valuable insights for policy and decision-making.

Elevated salinity in unconfined aquifers limits residents’ use of groundwater for drinking in agricultural settings in KSA. The study developed a probabilistic dermal risk assessment methodology for heavy metals exposure through washing and bathing activities in farms across the Qassim Region, which addressed the uncertainties associated with limited data and vagueness in site-specific exposure factors, such as skin surface area and body weight. Groundwater monitoring established the probabilities of Ba, Cd, Cr, Mn, and Zn levels exceeding the maximum allowable concentrations (MAC) as 0.03 mg/L, 0.003 mg/L, 0.15 mg/L, 0.01 mg/L, and 0.01 mg/L, respectively. A hazard index with a 0.99 probability of less than 1 indicates an insignificant non-cancer risk associated with dermal exposure. The study found an incremental lifetime cancer risk (ILCR) of 6E-5 for Cd and 8E-5 for Cr at median probability, less than the acceptable cancer risk of 1.0E-4. ILCR values of 3.2E-4 for Cd and 2.2E-04 for Cr at 0.9 probability remained lower than the corresponding values of 9E-4 (Cd) and 3.1E-4 (Cr) estimated for the MAC values recommended for KSA. Monte Carlo simulations highlighted Zn (59.5%), Cr (18.1%), and exposure time (10.5%) as the primary contributors to variations in non-cancer health risks to infants. Cd (60.1%) and Cr (46.2%) concentrations, along with exposure time (12.6% for Cd and 25.8% for Cr), were identified as key contributors to ILCR variations. The estimated heavy metal pollution indices at 0.95 probability indicate non-contaminated groundwater. The study offers insights into the health risks and guidelines for treating raw water at the household level, promoting agricultural sustainability in Saudi Arabia and elsewhere.