Search Results (92)

Reliable drinking-water production is difficult on remote islands where brackish-water delivery is intermittent, technical personnel are scarce, and reverse-osmosis plants are manually operated. This study presents an operational characterization of an Internet of Things (IoT) retrofit deployed in Santa Cruz, Galápagos; it is not a controlled before-and-after effectiveness evaluation. An ESP32-based M5Stack Tough controller, distributed ESP-NOW sensing nodes, relay–contactor interfaces, a binary pressure permissive, and a ThingSpeak cloud layer were integrated without replacing the existing pumps and membranes. The exported primary-flow channel contained 4,603,989 numeric observations, including 500 pre-official test readings. Operational analyses used 4,603,489 numeric observations from the official monitoring period; 4,603,340 values remained after nominal-range filtering, and positive flow had a median of 12 L/min (interquartile range: 11–15 L/min). Among 332 logged high-pressure commands, 326 were preceded by a low-pressure command (98.2% unbounded command-state consistency), whereas 275 occurred within a 120 s analytical bound (82.8%). The median low-to-high command delay was 27 s (interquartile range: 11–70 s). Four organizational representatives completed a published 41-item Industry 4.0 maturity instrument before and after deployment; the self-reported overall mean was 0.26 at baseline and 1.95 post-deployment, and these results are interpreted descriptively. Energy-consumption and production data were confidential and unavailable to the authors, while water-quality variables were not measured. The contribution is therefore a long-duration, local-first legacy retrofit with auditable telemetry and explicit limitations, rather than a claim of optimized desalination performance. Full article

Population growth, increasing water demands for data centers, and the need for more sustainable water practices are prompting advancement of next-generation water resource management strategies including water reuse. In the Midwestern United States (U.S.), where non-traditional approaches to augmenting water supply, including water reuse, are relatively new, full advanced water treatment (AWT), which includes microfiltration/ultrafiltration (MF/UF) and reverse osmosis (RO), produces a concentrate stream that is expensive to address (i.e., brine disposal). Carbon-based advanced treatment (CBAT), which combines ozonation, biofiltration, and granular activated carbon, has been shown to be a viable alternative with select advantages over the traditional RO approach, including the lack of brine generation. Two novel pilots were conducted in the Midwestern U.S., one at a large (>100 MGD) and one at a small (~10 MGD) wastewater reclamation facility (WRF), to provide proof of concept that CBAT could meet distinct regional needs. While additional demonstration data are ultimately needed for future regulatory approvals, results from the pilots showed that water quality objectives were met with treated water quality of <0.5 mg/L total Kjeldal nitrogen (TKN), <2 mg/L total organic carbon (TOC), and substantial reduction in constituents of emerging concern (CECs). If nitrate removal is required to meet drinking water standards (10 mg/L), additional treatment optimization at the source WRFs would be required. Areas for further research identified by this effort include mitigating the potential for ozonation to contribute to the formation of disinfection byproducts such as bromate and N-nitrosodimethylamine (NDMA). Along with the treatment performance demonstrated at these pilots, the study provided an opportunity to engage with key stakeholders to build trust in the AWT approach, which is critically important for regulatory and public acceptance. Based on two field-scale pilot studies in the U.S. Midwest, this paper analyzes CBAT application advantages and challenges in municipal water reuse and identifies research directions for the industry. Full article

Many Greek islands host geothermal springs whose waters can be desalinated to produce drinking water. Some of these waters contain meaningful concentrations of the valuable Rb⁺ and Cs⁺ ions, which, when extracted from the desalination brine as RbCl and CsCl salts, can yield revenues exceeding the freshwater production costs. We demonstrate the use of reverse osmosis (RO) to produce freshwater and apply theoretical simulations to assess a proven extraction method applied to the RO retentate of geothermal water from Samothrace, characterized by [Rb⁺] = 2.72, [Cs⁺] = 0.55, [K⁺] = 514, [Na⁺] = 3759 (all in mg/L) and pH 6. The extraction method, developed by the authors, relies on ion exchange using a PES-coated Zn-hexacyanoferrate sorbent with high affinity for monovalent cations (no affinity for multi-valent cations), followed by a unique ion-chromatography separation. We show that the production cost remains <25% of the salts’ market price, with ROI of ~4.5 years. Full article

Heavy metal contamination of drinking water remains a persistent global challenge, exacerbated by salinity, industrial discharge, and the limitations of existing membrane technologies that are constrained by permeability–selectivity trade-offs. In this study, we develop a hybrid thin film nanocomposite (TFN) forward osmosis (FO) membrane by incorporating a zirconium-based metal–organic framework (UiO-66) and its conductive polymer-functionalized analogue (PANI@UiO-66) into the polyamide active layer via interfacial polymerization. The incorporation of UiO-66 enhances water transport through the introduction of hydrophilic microporous domains, while the polyaniline coating modulates nanoscale transport pathways and interfacial interactions. Systematic variation in filler type and loading reveals distinct functional roles of the two fillers. Membranes incorporating bare UiO-66 exhibit increased water flux, attributed to facilitated transport through MOF-derived nanochannels, but show a moderate increase in reverse solute flux. In contrast, PANI@UiO-66 incorporation results in reduced water flux but significantly suppresses reverse solute flux and enhances chromium rejection, indicating improved control over selective transport. At an optimal loading of 0.15 wt% (TFN-PU3), the membrane demonstrates an improved balance between water permeability and solute selectivity compared to the pristine thin film composite (TFC) membrane under FO conditions. The observed performance is attributed to the combined effects of modified transport pathways and interfacial interactions introduced by the hybrid filler system. The results highlight the potential of conductive polymer–MOF hybridization as a strategy for tuning membrane performance. This work provides a practical framework for designing TFN membranes for selective heavy-metal removal in saline and complex water environments. Full article

The provision of potable water for armed forces at their operational sites necessitates a robust treatment chain to ensure the production of safe drinking water from potentially contaminated local water sources. Relying on single-use water bottles is not considered an eco-friendly option and on-site production may exhibit limited efficiency depending on the water contamination. This study therefore aimed to define a mobile processing chain that could efficiently produce drinking water on-site while offering a multi-barrier level of protection. To evaluate the system, contaminated water was prepared from different water sources and then spiked with various inorganic contaminants (metals, anions: Cl⁻, F⁻, I⁻, NO₂⁻, NO₃⁻, SO₄²⁻, CN⁻), organic contaminants (e.g., pesticides, petroleum hydrocarbons, polycyclic aromatic hydrocarbons, chlorinated solvents), and energetic compound (perchlorate) at levels ranging from 5 to 50 times the standard water quality criteria. A specific treatment process was defined optimized and evaluated at flow rates reaching 500 L/h. This treatment chain includes the following: a sediment filter, a greensand filter, a cation exchange resin, an anion exchange resin, an activated carbon adsorption filter, ultrafiltration, a UV lamp, and a reverse osmosis (RO) unit. This treatment system successfully met all water quality criteria, providing a reliable and effective alternative to an RO-only treatment regime. Full article

In arid and water-stressed regions, groundwater desalination plants are critical for ensuring reliable potable water supplies, making improvements in their operational efficiency and cost effectiveness a priority for utilities. In many such facilities, lime and soda ash softening remain common pretreatment practices, which increase chemical consumption and sludge generation, prompting the need for alternative low-chemical strategies. This study evaluates the technical, operational, and economic implications of transitioning a full-scale brackish groundwater desalination plant, from lime–soda ash softening (old plan) to a low-chemical pretreatment strategy based on antiscalant dosing (new plan) upstream of reverse osmosis (RO). Key parameters, including pH, total hardness, calcium and magnesium hardness, silica, iron, alkalinity, and total dissolved solids (TDS), were measured and compared at multiple locations within the treatment plant under both the old and new plans. Removing lime and soda ash caused higher levels of hardness, alkalinity, and silica in the water before RO treatment, increasing the risk of scaling. Operationally, the feed pressure increased from 11.43 ± 0.16 bar (old plan) to a peak of 25.50 ± 0.10 bar in the new plan, accompanied by a decline in water production. Chemical cleaning effectively restored performance, reducing feed pressure to 13.13 ± 0.05 bar, confirming that fouling and scaling were the primary, reversible causes. Despite these challenges, the plant consistently produced water that complied with Saudi Standards for Unbottled Drinking Water (e.g., pH = 7.18 ± 0.09, TDS = 978.27 ± 9.26 mg/L). Economically, the new strategy reduced operating expenditure by approximately 54% (0.295 → 0.135 $/m³), largely due to substantial reductions in chemical and sludge handling costs, although these savings were partially offset by higher energy consumption and more frequent membrane maintenance. Overall, the findings emphasize the importance of systematic performance evaluation during operational transitions, providing guidance for utilities seeking to optimize pretreatment design while maintaining compliance, long-term membrane protection, and environmental sustainability. Full article

Coastal Bangladesh faces severe drinking water scarcity due to salinity intrusion. To address this challenge, the study assesses the socio-technical and economic factors shaping the performance of small-scale reverse osmosis (RO) desalination plants through field audits, household surveys, stakeholder interviews, and water quality analysis. Community acceptance was evaluated using the Theory of Planned Behavior (TPB). Feedwater was highly contaminated, with average TDS 3732.63 mg/L, hardness 636.36 mg/L, iron (Fe) 3.23 mg/L, and turbidity 14.63 NTU. Despite this, RO systems demonstrated strong performance, achieving removal efficiencies of 95.15% for salts, 95.95% for hardness, and 91.67% for alkalinity, with an average recovery rate of 37.25% (range: 20–60%). Treated water met WHO and Bangladesh standards, with mean concentrations of TDS (195.54 mg/L), Fe (0.21 mg/L), arsenic (0.0085 mg/L), and turbidity (1.09 NTU). However, inadequate operator training and a lack of maintenance threaten sustainability. Energy consumption increased by 0.1 kWh/m³ per 1000 mg/L rise in salinity, while financial constraints hinder membrane replacement. TPB analysis revealed positive attitudes and perceived behavioral control as key adoption drivers. Untreated brine discharge (mean TDS 12,900 mg/L) posed significant environmental risks. This study provides micro-level insights to inform policy and strengthen the sustainability of decentralized RO systems in climate-vulnerable coastal regions. Full article

Reverse osmosis (RO) is the most widely used technology in seawater desalination, accounting for around 70% of installations worldwide due to its efficiency and lower energy consumption compared to conventional thermal processes. However, a major challenge for RO is concentration polarization (CP), a phenomenon that reduces permeate flow, increases osmotic pressure, and compromises salt rejection, affecting the useful life of the membranes. In this work, an RO pilot plant was operated with synthetic solutions ranging from 4830 to 39,850 mg L⁻¹ at pressures between 0.69 and 5.79 MPa, to analyze and predict CP behavior. The results obtained showed salt rejection percentages ranging from 98.80% to 99.63%. The adjusted polynomial models presented correlation coefficients close to unity, which supports their high predictive capacity and statistical robustness for estimating the behavior of CP as a function of pressure. These models were implemented in Python software, allowing for the simulation of non-experimental scenarios and the anticipation of critical conditions that could compromise the RO process. Therefore, this work provides a robust predictive simulation tool to optimize RO processes and ensure the sustainable supply of drinking water in regions with water availability problems. Full article

The plateaus of north-central Mexico have an arid to semiarid climate and groundwater naturally contaminated with inorganic arsenic (iAs) and fluoride (F). Like other arid and semiarid areas, this region faces great challenges to maintain a safe supply of drinking and irrigation water. Studies conducted in the past few decades on various locations within this region have reported groundwater iAs, F, and nitrate-nitrogen (NO₃-N), and either their source, enrichment processes, health risks, and/or potential water treatments. The relevant findings are analyzed and condensed here to provide an overview of the groundwater situation of the region. Studies identify volcanic rocks (rhyolite) and their weathering products (clays) as the main sources of iAs and F and report that these solutes become enriched through evaporation and residence time. In contrast, NO₃-N is reported as anthropogenic, with the highest concentrations found in large urban centers and in agricultural and livestock farm areas. Health risks are high since the hot spots of contamination correspond to populated areas. Health problems associated with NO₃-N in drinking water may be underestimated. Removal technologies of the contaminants remain at the laboratory or pilot stage, except for the reverse osmosis filtration units fitted to selected wells within the state of Chihuahua. A recent approach to supplying drinking water free of iAs and F to two urban centers consisted of switching from groundwater to surface water. Incipient research currently focuses on the potential repercussions of irrigating crops with As-rich water. The groundwater predicaments concerning contamination, public health impact, and irrigation suitability depicted here can be applied to semiarid areas worldwide. Full article

Domestic showers are critical points of human exposure to microbial biofilms, which may harbor opportunistic pathogens such as Legionella spp. and nontuberculous Mycobacterium. However, biofilm development in reverse osmosis (RO)-treated drinking water systems remains poorly understood. We tested whether shower plumbing material (flexible polymer hose versus showerhead with inline polyethersulfone filter) and seasonal water variations influence biofilm community assembly. In a controlled field study, commercial shower systems were deployed in households supplied with RO-treated tap water from the KAUST Seawater Desalination Plant; biofilm samples were collected from hoses and filters over 3–17 months. Flow cytometry and 16S rRNA gene amplicon sequencing characterized microbial abundance, diversity, and taxonomic composition. We found that alpha diversity, measured by observed OTUs, was uniformly low, reflecting ultra-low biomass in RO-treated tap water. Beta diversity analyses revealed clear clustering by material type, with hoses exhibiting greater richness and evenness than filters. Core taxa—Pelomonas, Blastomonas, and Porphyrobacter—dominated both biofilm types, suggesting adaptation to low-nutrient, chlorinated conditions. Overall, our results demonstrate that ultra-low-nutrient RO tap water still supports the formation of material-driven, low-diversity biofilms dominated by oligotrophic taxa, underscoring plumbing-material choice as a critical factor for safeguarding shower water quality. These findings advance our understanding of biofilm ecology in RO-treated systems, informing strategies to mitigate potential health risks in shower water. Full article

The growing presence of organic micropollutants (OMPs) in water sources is a major health concern. Successful removal of OMPs from water sources and ensuring the cleanliness of drinking water has become an important topic in recent years. In this study, 15 nanofiltration (NF) and reverse osmosis (RO) commercial membranes were selected and their potential to remove 10 frequently encountered OMPs in drinking water, with systematically different chemical characteristics, was evaluated. To quickly identify the most promising membranes, high throughput dead-end filtrations were initially conducted. Subsequently, the 4 best performing membranes were used in a more relevant high-throughput cross-flow filtration. Membrane performance was evaluated by analyzing OMP concentrations in the feed and retentates of the different membranes using ultra-high-performance liquid chromatography-mass spectrometry (UHPLC-MS). This study identified NF 90 (Dow), NF 270 (Dow), NFX (Synder) and TS80 (Trisep) as membranes with superior performance, with a permeance between 3 and 7 L.${\mathrm{m}}^{-2}$.h⁻¹.bar⁻¹ and retentions that were generally around 90%, except for NFX which showed slightly lower retentions. Full article

This study investigated the presence and concentration of selected phthalates in municipal tap waters and purified waters sourced from domestic water purifiers and municipal reverse osmosis-based supplies. Five target compounds: Diethyl phthalate (DEP), Diisobutyl phthalate (DiBP), Butyl octyl phthalate (BOP), Dibutyl phthalate (DBP), and bis(2-ethylhexyl) phthalate (DEHP) were identified and quantified in the samples using the solid-phase microextraction gas chromatography-mass spectrometry (SPME-GC/MS) method. The analytical protocol demonstrated good sensitivity, precision, and accuracy, with low limits of detection and quantification, making it suitable for routine monitoring applications. Phthalates were detected in all samples, including both inlet and treated water, highlighting their widespread occurrence. The results show a significant percentage of reduction in total phthalate concentrations (from 4% to 53%; 30% on average) in purified water samples compared to untreated inlet water, thereby indicating the potential efficacy of such systems in reducing organic pollutants. Risk assessment based on the EFSA guidelines showed that the estimated daily intakes for all detected phthalates remained well below tolerable daily intake limits for both adults and toddlers. The findings underscore the importance of monitoring phthalates in drinking water and support the implementation of regular maintenance strategies for filtration devices. The analytical approach developed may be adopted as a cost-effective tool for water quality assessment and offers promising potential for broader application in public health and commercial water treatment systems. Full article

N-Nitrosodimethylamine (NDMA) is a widely recognized disinfection by-product that poses significant carcinogenic risks in drinking water. Conventional methods for NDMA removal, such as nanofiltration and reverse osmosis membranes, have limited efficacy due to NDMA’s small molecular weight and polar properties. Advanced oxidation processes (AOPs) have shown promise, but traditional Fenton processes often fall short due to the chemical structure of nitrosamines in NDMA. This study proposes a novel, cost-effective approach using a one-step carbonization method to synthesize a catalyst from ferric ammonium citrate (FAC). The resulting FAC-600 integrates zero-valent iron and iron carbide with carbon-based functional groups, enhancing catalytic and electron transport activities. Our experiments demonstrated that the FAC-600/persulfate (PS) AOP system achieves over 90% NDMA removal across a wide concentration range (50 μg L⁻¹ to 1000 μg L ⁻¹) with a limited dosage of 0.5 g L⁻¹. Mechanistic insights revealed that superoxide and hydroxyl radicals dominate NDMA degradation, facilitated by the presence of dissolved oxygen and PS. This study underscores the potential of the FAC-600/PS AOP system as a robust and efficient solution for NDMA removal, promising safer drinking water through practical application. Full article

Elevated fluoride levels in drinking water pose a significant health risk for communities relying on groundwater in the Ethiopian Central Rift Valley. This study aims at characterizing real groundwater samples from the Ethiopian Central Rift Valley and evaluating the performance of an integrated membrane process based on reverse osmosis (RO) and membrane crystallization (MCr) for fluoride removal and its recovery as mixed fluoride salts. Groundwater analysis revealed fluoride concentrations of 20.8 mgL⁻¹ at the Meki-01 site and 22.7 mgL⁻¹ at the Meki-02 site, both exceeding the WHO guideline of 1.5 mgL⁻¹. In addition, total dissolved solids exceeded 1000 mgL⁻¹ at both sites, classifying the water as brackish. A commercial RO membrane demonstrated excellent fluoride and ion rejection, with fluoride removal rates exceeding 99%. The total dissolved solids (TDS) removal efficiency reached 89%. The mean water permeability of the membrane was 4.52 Lm⁻²h⁻¹bar⁻¹. The retentate produced in the RO unit reached a concentration of 70 mgL⁻¹, which was then treated using osmotic membrane distillation–crystallization (OMD-Cr) and/or vacuum membrane crystallization (VM-Cr). This process facilitated the recovery of mixed salts while achieving an almost zero-liquid discharge. The study confirms the successful removal of fluoride and its recovery as mixed salt, along with the recovery of water in an environmentally friendly and manageable way. Full article

Radionuclide-contaminated water is carcinogenic and poses numerous severe health risks and environmental dangers. Thus, effective removal techniques are required to ensure the safety of drinking water sources. This article overviews several methods to remove naturally occurring radioactive materials (NORMs) from water, including adsorption, coagulation, reverse osmosis, ion exchange, electrodialysis, iron manganese filtration, and membrane filtration. A search is conducted in different scientific databases to identify relevant articles, reviews, and studies on removing radionuclides from water. The overarching goal of this article is to deepen the understanding of the techniques available for radionuclide removal from water and to foster the creation of innovative solutions for water contamination concerns. Each technique is examined in terms of its efficiency, cost-effectiveness, and sustainability in removing specific radionuclides from water sources. The advantages and limitations of these techniques are discussed, highlighting the importance of selecting the most appropriate method based on the characteristics of the radionuclides and the water source. Different methods can be combined for the more effective removal of radionuclides from water, such as coagulation and filtration, reverse osmosis, and ion exchange. The treatment of water contaminated with radionuclides requires prior laboratory work and pilot-scale tests to determine the most suitable, cost-effective, and environmentally friendly method. Full article