ABSTRACT The graphical abstract presents the evolution of seawater desalination in three stages. The left section shows conventional reverse osmosis and thermal desalination systems, with challenges including high energy consumption, carbon emissions, operating costs, and brine discharge. The central section presents bibliometric and citation-network-based main-path and cluster analysis of 4,059 Web of Science publications, identifying four major technology clusters: RO–FO–PRO hybrid systems, solar photothermal materials, membrane distillation, and CDI/FCDI electrochemical desalination. The right section depicts future sustainable desalination systems integrating renewable energy, low-carbon operation, advanced materials, smart monitoring, AI-driven optimization, and decentralized water supply. The overall progression is from standalone process-oriented desalination toward integrated sustainability-driven water–energy systems. Seawater desalination has become an important solution to global freshwater scarcity, but challenges related to energy consumption, operational costs, and environmental sustainability remain significant. Therefore, the primary purpose of this study is to systematically identify the major technological development pathways, research clusters, and future research directions shaping sustainable seawater desalination systems. Using bibliometric and citation-network analyses of 4,059 articles from the Web of Science database, this study integrates main path analysis, cluster analysis, and keyword frequency analysis to examine the technological evolution and cost–benefit characteristics of desalination technologies. The results indicate that reverse osmosis remains the dominant and most economically competitive technology due to its mature infrastructure and relatively low energy requirements. Membrane distillation has attracted increasing attention for treating high-salinity brines and utilizing low-grade heat sources. In addition, solar-driven and electrically driven desalination technologies demonstrate strong potential for improving sustainability and operational efficiency. Overall, this study maps the knowledge structure and technological trajectories of desalination research and provides insights into the development of energy-efficient, low-carbon, and sustainability-driven water supply systems.
ABSTRACT The Wangdonggou ecological small watershed was taken as the research object. Based on the hourly monitoring data from 2020 to 2025, the multi-time-scale analysis framework of ‘hour-day-month-aggregation period’ was constructed, and the time-lag cross-correlation was adopted. The vertical lag response law of soil moisture at different depths to rainfall was systematically quantified. The core innovations are as follows: methodologically, the study achieved precise identification of the time lag between rainfall and soil water; in theory, the coupling relationship between ‘rainfall intensity, infiltration depth and lag response period’ has been quantitatively elucidated; in practice, a vegetation management plan has been proposed that prioritises herbs and shrubs, whilst requiring careful selection of tree species. The results indicate that the lag response period for the shallow layer (0–28 cm), middle layer (28–100 cm) and deep layer (100–255 cm) are 3–4 h, 23–24 h and 6–7 days, respectively; as rainfall intensity increases from light to heavy rain, the lag response period in the deep layer shortens from 9 to 3 days. This study provides a scientific basis for research into the ‘rainfall intensity-infiltration-root system’ coupling mechanisms on the Loess Plateau and for the construction of sustainable ecosystems.
ABSTRACT Graphical abstract showing Fenton-like oxidation of phenalkamine condensate using FeNP, achieving 85.11% COD removal from an initial COD of 140,000 mg/L. SEM analysis shows agglomerated spherical particles, while FTIR confirms Fe–O and other characteristic bonds. XRD identifies danalite, spinelloid, hematite, and iron oxide phases. Catalyst reusability was evaluated over four treatment cycles. Phenalkamine, a reaction product of cardanol, formaldehyde, and amines, is a highly valuable commercial product. The phenalkamine condensate is characterized by high pH, high chemical oxygen demand (COD) (140,000 mg/L), and comparatively low biochemical oxygen demand (BOD), making it challenging to degrade. In this study, heterogeneous Fenton-like oxidation using commercially obtained iron oxide nanoparticles (FeNPs) was investigated for treating real phenalkamine condensate. The FeNPs were characterized using SEM-EDS, XRD, FTIR, and BET techniques. XRD analysis confirmed hematite (Fe2O3) as the dominant crystalline phase with minor mixed crystalline reflections. The investigation also explored the influence of different parameters, including initial pH, H2O2 dosage, catalyst dosage, reaction time, and temperature. Optimal conditions are as follows: pH = 3.5, H2O2/COD ratio = 2, H2O2/FeNP ratio = 10, reaction period of 300 min at 313 K, and the maximum COD removal efficiency reached 85.11%. The degradation followed pseudo-first-order kinetics with a reaction rate constant of 0.00591 min−1 and an activation energy of 15.75 kJ/mol, indicating diffusion-controlled reaction. Comparison with conventional Fenton's oxidation demonstrated the superior performance of the FeNP catalyst. Furthermore, catalyst reusability studies revealed that the FeNPs could be reused for up to three cycles. This research contributes significant insights into the utilization of FeNPs as efficient catalysts for the degradation of phenalkamine condensate.
ABSTRACT Graphical workflow illustrating the development of a principal component analysis (PCA)-based linearly weighted water quality index (WQILW) for wetland ecosystems. The process begins with two wetland classes – low-lying marshlands and perennial wetlands – and 18 measured surface water quality parameters. Statistically significant variables are selected through ANOVA and reduced to a minimum data set using PCA. The selected variables are normalized, weighted according to PCA-derived coefficients, and aggregated into the final WQILW. The workflow incorporates the geographic distribution of wetlands in Goa, multivariate analysis, and index computation, resulting in a water quality index that significantly differentiates perennial wetlands from low-lying marshlands (p=0.001). Wetlands are ecologically significant yet vulnerable ecosystems whose surface water quality is often difficult to assess due to their unique ecological character and the complexity of multivariate datasets. While numerous studies have applied principal component analysis (PCA) to water quality data, most have focused on generalized indices or single wetland types, limiting their ability to capture ecosystem-specific differences. Few studies have developed a PCA-based, linearly weighted water quality index (WQILW) tailored for differentiating between two ecologically distinct wetland types: low-lying marshlands and perennial wetlands in Goa, India. Eighteen water quality parameters from 38 notified wetlands were analysed, with 10 key variables selected through PCA to form a minimum data set (MDS). The MDS was normalized using scoring functions based on ecological relevance and integrated using PCA-derived weights to compute the WQILW. Compared with established indices (NSF-WQI, WA-WQI, and CCME-WQI), the WQILW demonstrated superior discriminatory power, significantly differentiating wetland types (p < 0.001). Perennial wetlands showed higher water quality (0.91) than low-lying marshlands (0.75). These results highlight the need for wetland-type-specific indices that incorporate both statistical rigour and ecological context, for a reproducible and sensitive framework for regional wetland monitoring and management under the Wetlands Rules, 2017.
ABSTRACT Overall Description: A conceptual flowchart divided into three main vertical sections: Sampling, Laboratory Analysis, and Policy Recommendations, illustrating that bottled mineral water in Tehran may harbor antibiotic-resistant Pseudomonas aeruginosa undetectable by standard fecal indicator tests. Section 1: Sampling States "100 samples, Tehran retail, Apr–Sep 2019". Section 2: Laboratory Analysis Highlights "Seasonal contamination" occurring exclusively during warm months (May, July, September). It shows a green checkmark next to "Pseudomonas aeruginosa" and indicates negative results for "Coliforms & E.coli". Below this, it lists the Resistance Profile (n=5): Resistant to SXT, CFM, CFLEX; Susceptible to GM, AK, IMI, CO, CRO. It also notes the presence of ESBL Genes: blaTEM-1 (100%) and blaCTX-M (40%). Section 3: Policy Recommendation Features a "CALL TO ACTION" banner to "Update Global Bottled Water Standards". It highlights "THE BLIND SPOT" with three bullet points: Fecal indicators do NOT detect this threat (All Negative), ESBL genes present (blaCTX-M 40%), and Risk in WarmMonths (Secondary contamination). Finally, it lists "RECOMMENDED ACTIONS": Add P. aeruginosa to mandatory screening (ISO 16266), Require Temperature Labelingon packaging, and Shift surveillance from Factory to Retail outlets. Bottled mineral water is widely promoted as a ‘safe’ and ‘pure’ alternative to tap water, especially in urban settings such as Tehran. However, this perception may be dangerously inaccurate, as conventional safety assessments rely solely on fecal indicator bacteria – such as coliforms and Escherichia coli – which fail to detect non-fecal opportunistic pathogens like Pseudomonas aeruginosa. In a six-month study (spring to autumn 2019), we randomly collected 100 bottled mineral water samples from retail outlets across Tehran and analyzed them for P. aeruginosa, antimicrobial resistance profiles, and extended-spectrum beta-lactamase (ESBL)-encoding genes (bla TEM-1, bla CTX-M, bla SHV), alongside standard fecal indicators. P. aeruginosa was isolated from 5% of samples (5/100), exclusively during warm months (May, July, September; p = 0.032), suggesting temperature-dependent secondary contamination. Critically, all contaminated samples tested negative for fecal indicators, revealing a major blind spot in current regulatory frameworks. All isolates were susceptible to gentamicin, amikacin, imipenem, colistin, and ceftriaxone, but showed 100% resistance to trimethoprim–sulfamethoxazole. Genotypically, all harbored blaTEM-1, 40% carried bla CTX-M (indicative of recent human or hospital-associated origins), and none carried bla SHV. These findings demonstrate that bottled water passing standard fecal indicator tests can still harbor ESBL-producing P. aeruginosa, likely due to post-bottling contamination during warm-season storage or transport. As the first comprehensive report from the Middle East to simultaneously assess fecal indicators and ESBL genes in bottled water, this study calls for urgent updates to international safety standards – including Codex Stan 227-2001 and U.S. FDA regulations (21 CFR Part 165)—to include mandatory screening for opportunistic pathogens, temperature labeling on packaging, and enhanced retail surveillance, particularly in warm-climate regions. This is not only a microbiological concern but a pressing public health policy imperative.
