Environmental Science: Water Research & Technology最新文献

Disinfection by-products (DBPs) are formed during the chlorination of drinking water and present a risk to human health, with brominated DBPs identified as more toxic than their chlorinated analogues. The most widely regulated DBPs are trihalomethanes (THMs), but increasingly focus is on haloacetic acids (HAAs), including consideration of all nine brominated and chlorinated HAAs for regulation (HAA9). Recently, aliphatic carbonyl compounds have been recognised as important DBP precursors and to favour bromine incorporation. This research specifically focuses on smaller aliphatic carbonyl precursors, enabling identification of the molecular-level features that are most significant for increasing the risk of forming the more toxic brominated DBPs and for reducing compliance with potential HAA9 regulations. This showed that β-keto acids present a particular problem due to their high propensity for bromination and Br-HAA formation. However, in the context of HAA9 standards, the neutral ester compounds were equally significant due to formation of the mixed chlorinated and brominated bromochloroacetic acid, which is within the currently unregulated HAAs. The enhanced understanding of Br-DBP formation from such hydrophilic organic precursors is important as such compounds are poorly removed by standard coagulation water treatment and are formed during oxidative treatment processes. Consequently, source waters containing these compounds and bromide are at significant risk of forming unacceptable levels of HAA9, a problem which becomes increasingly urgent as pressure on resources forces reliance on poorer quality drinking water sources containing higher levels of bromide. Further, the work shows that current monitoring approaches are inadequate when we need to consider HAA9.

Textile industrial wastewater contains high levels of chemical and nutrient pollutants, posing significant environmental challenges that conventional physicochemical treatments inadequately address, highlighting the need for eco-friendly biological alternatives utilizing native algal isolates. This study investigates the potential of native algal isolates for sustainable wastewater treatment. Algal strains were isolated from textile effluents and identified based on morphological characteristics and molecular sequencing as Cyanobacterium stanieri DSA01 (CS), Desertifilum salkalinema DSA02 (DS), and Ciimarium marinum DSA03 (CM). Three algal isolates were cultivated in 30 day batch experiments using two textile wastewater samples (TW1 and TW2) to evaluate treatment efficacy for chemical oxygen demand (COD) and key nutrients (e.g., nitrate, ammonia and phosphate). The maximum COD removal by DS was 88.49 ± 1.77% on day 5 in TW1 and 63.52 ± 1.27% on day 15 in TW2. DS consistently demonstrated nutrient removal efficiencies exceeding 50% in both TW1 and TW2. Biochemical analysis revealed a significant increase in protein content, indicating efficient nutrient utilization. The treated wastewater enhanced the shoot and root development of Vigna radiata seeds, confirming pollutant reduction and demonstrating potential for industrial reuse, agricultural irrigation, and aquatic ecosystem protection, thereby promoting sustainable wastewater management. This study confirms the applicability of native algal isolates as an effective and sustainable strategy for managing textile wastewater.

Fluoride pollution in water from industries such as photovoltaics and semiconductors has posed a growing environmental challenge, necessitating effective methods for trace fluoride (F⁻) removal. This study developed lanthanum-loaded magnetic hydrogel beads (CH-Fe-MMT-La) via a sol–gel method for deep F⁻ elimination from industrial effluents. Characterization confirmed the incorporation of La³⁺. The adsorbent achieved 96.35% removal efficiency for low-concentration F⁻ (10.0–20.0 mg L⁻¹) with 16.06 mg g⁻¹ of Langmuir capacity at 3.0 g L⁻¹ dosage and 6 h contact time. Kinetic data followed a pseudo-second order model (R² > 0.999), indicating chemisorption, and thermodynamic results revealed endothermic behavior (ΔH = +48.7 kJ mol⁻¹). The material retained >90% efficiency over a pH range of 4–9 and performed better at elevated temperatures. Field application to electroplating wastewater (F⁻: 218.7–11 604 mg L⁻¹) using a Ca(OH)₂ precipitation–adsorption hybrid process reduced the concentration of F⁻ to 1.24–1.65 mg L⁻¹, meeting EPA standards. This work demonstrates the first use of magnetic hydrogel systems for multi-stage F⁻ removal and offers a practical solution for deep treatment.

Non-targeted analysis was used to characterize the dissolved organic matter in water from two swimming pools in Nanjing and Changzhou, eastern China. A total of 112 coexisting compounds (level 2b) were detected in both pools using the MassBank database. Source tracking identified 20 compounds from tap water, 19 from sweat, 1 from urine, and 2 from mosquito repellents, including amino acids, coumarins, alcohols, N-heterocycles, alkaloids, carboxylic acids, terpenoids, ketones, and esters. The number of coumarins accounted for 10% of the common compounds in tap water, 21% in sweat, 100% in urine, and 50% in repellents, confirming tap water, biological excretions, and cosmetics as the coumarin sources in pool water. Concentrations ranged from ng L⁻¹ (pool and tap water) to μg L⁻¹ (sweat and urine) and mg L⁻¹ (repellents). Breakthrough tests revealed that sand filtration, China's primary treatment, removed <5.8% of the coumarins due to their hydrophilicity (log P < 5). In simulated chlorination of tap water spiked with 100 ng L⁻¹ of each coumarin, only 0.26 ng L⁻¹ of 3-Cl-7-OH-4-CH₃-coumarin was detected, while the concentrations of trichloroacetic acid, iodoacetic acid, bromodichloromethane, dibromochloromethane, and trichloroacetaldehyde increased by 0.38–3.3 μg L⁻¹ (4.1–36%), 0.16–2.9 μg L⁻¹ (1.7–31%), 0.70–3.9 μg L⁻¹ (3.8–21%), 2.2–8.0 μg L⁻¹ (4.5–12%), and 0.9–2.4 μg L⁻¹ (4.8–13%), respectively, due to coumarin transformation under high chlorine doses and long reaction times (12 h). This study demonstrates that coumarins act as disinfection byproduct precursors in swimming pool water, and their accumulation may increase DBP levels, posing health risks to swimmers, thereby filling a knowledge gap in pool water DOM research.

Microplastics (MPs) have become a ubiquitous environmental pollutant, with water acting as the main vector for their transport and widespread dissemination across natural and engineered systems. Municipal wastewater treatment plants (WWTPs) play a pivotal role as both major sinks and continuous point sources of MPs, as incomplete removal during treatment, combined with high effluent flow rates and sludge reuse, leads to significant emissions to aquatic and terrestrial environments. Growing awareness of this issue is driving the development of increasingly stringent regulatory frameworks in the water sector. However, the absence of standardized and policy-relevant analytical methodologies has so far hindered the explicit regulation of MPs. Current monitoring strategies rely predominantly on particle-based approaches using visual and spectroscopic techniques, which are labor-intensive, observer-dependent and prone to substantial underestimation, particularly for small particles. Therefore, they are poorly suited for regulatory implementation and process control. While thermoanalytical techniques such as pyrolysis- and thermodesorption-gas chromatography coupled to mass spectrometry (Py-GC/MS and TD-GC/MS) provide valuable insights into polymer composition and mass-based information, they remain costly, time-consuming and limited in their ability to deliver rapid, comprehensive quantification of total plastic content in complex (waste)water matrices. This Perspective critically reviews the state of the art in MP quantification, highlights the urgent need for robust mass-based metrics compatible with regulatory and operational requirements, and introduces a practical, cost-effective mass-based method developed by our research group and Captoplastic S. L., and commercialized through the start-up Captoplastic S.L. Its applicability is finally demonstrated through a municipal WWTP case study.

Pit latrine filling poses a major challenge in developing countries. This study investigated the effect of faecal sludge-derived biochar (FSB) on anaerobic degradation, the dominant process in pit latrines, using synthetic human excreta under laboratory conditions simulating wet pit environments. Results show that FSB addition significantly increased hydrolysis rate and shortened lag phase by up to 1.5 days. However, this enhancement did not translate into improved overall degradation, as volatile solids (VS) reduction decreased under FSB addition, while only minor changes were observed in methane and total gas production. This decoupling is attributed to redistribution of organic carbon from gaseous products toward microbial biomass and extracellular matrices, as reflected by elevated extracellular polymeric substance (EPS) carbohydrate concentrations. Microbial community analysis revealed a targeted restructuring toward biofilm-associated hydrolytic and methanogenic populations under FSB amendment, characterised by enrichment of metabolically versatile methanogens (Methanosarcina) and proteolytic fermenters. Overall, these findings indicate that FSB promotes microbial aggregation and stabilised anaerobic processes but does not enhance net solids degradation, and therefore the findings do not support the recommendation of FSB as a pit latrine additive for reducing pit filling.

Population growth, climate change, and urbanisation significantly contribute to environmental stress, particularly through the depletion of finite resources like clean, easily accessible freshwater. In the water industry, the supply chain must become more independent, shifting from the prevailing linear delivery model to a circular economy. This shift can be achieved by adopting advanced treatment methods to ensure high-quality treated water and minimising waste and emissions. A transition to a circular economy can offer an opportunity to address sustainability issues in multiple sectors. For example, the water and energy nexus recognises that these two sectors are inextricably linked. Integrating green hydrogen production and wastewater treatment (WWT) has been identified as a promising strategy as part of the water-energy nexus, which advances the circular economy. When the green hydrogen economy uses treated wastewater as a feedstock, contributing to water reuse, the water industry can further enhance the sustainability of this approach by utilising co-products from hydrogen synthesis, such as high-purity oxygen. This oxygen can then be employed in various stages of WWT, including aeration and producing key reagents such as ozone and hydrogen peroxide, aiming to improve treatment efficiency and reduce emissions. Accordingly, this study examines how such applications can enhance circularity within the water sector. The principal findings were: (i) integrating green hydrogen production with WWT offers promising environmental and economic benefits but requires deeper technical, regulatory, and stakeholder alignment; (ii) optimising co-product oxygen utilisation in aeration and advanced treatment can help enhance WWT performance and economic viability; (iii) future research should prioritise techno-economic assessments, pilot-scale demonstrations, and system-wide integration studies to enable successful implementation of this circular and sustainable approach.

Using long-term monitoring and machine learning, this study links upstream hydrometeorology, reservoir processes, and operations to source water conditions relevant to trihalomethane (THM) formation risk at the Mediterranean Ter drinking water treatment plant (DWTP) in Spain, supplied by a three-reservoir cascade (Sau–Susqueda–Pasteral). Based on exploratory analyses, three target variables were selected as indicators of THM formation risk: dissolved organic carbon (DOC) and water temperature (WT) at the DWTP inlet, and fluorescent dissolved organic matter (fDOM) at the Susqueda withdrawal depth. Permutation importance results using Random Forest and LSTM models indicated that withdrawal-layer conditions at Susqueda dominate downstream variability: DOC was most strongly associated with extracted fDOM and other withdrawal water quality variables, whereas inlet WT was primarily controlled by Susqueda withdrawal temperature. For fDOM at Susqueda, reservoir storage volume emerged as a major driver, highlighting the influence of water availability, retention time, and stratification on DOM dynamics. Optimized LSTM models predicted the three target variables with strong validation skill (R² and KGE > 0.8). Scenario simulations identified seasonal windows of opportunity for THM risk reduction, with selective withdrawal targeting low-fDOM or cooler layers reducing indicator-based THM formation risk at the DWTP inlet, particularly during warm stratified periods and post-summer rainfall transitions. The effectiveness of this strategy was event-dependent and constrained by reservoir levels and gate accessibility. These results highlight opportunities to reduce DBP formation risk through upstream management, supporting a shift from end-of-pipe control to multi-barrier strategies, particularly in regions facing increasing hydroclimatic stress.

Access to safe drinking water remains a critical challenge in remote northern communities in the Arctic, particularly those served by decentralized water systems. This study aims to assess overall access to domestic water and identify main challenges, including water quality assessment, with regard to various water use scenarios and household practices in communities served with truck-to-cistern distribution systems. A case study was conducted with the community of Mittimatalik (Pond Inlet) in Nunavut, Canada, and included a randomized household survey and water quality analyses for priority contaminants. Physicochemical parameters, microbial indicators, opportunistic pathogens, and heavy metals were evaluated from water sources to the point-of-use. Results revealed deteriorating water quality throughout the distribution system, with depleted chlorine residuals and elevated turbidity, relative to water quality guidelines. While source water showed relatively good quality, 19.4% of tap samples contained total coliforms, and Pseudomonas aeruginosa was detected in 32.3% of tap samples, suggesting potential biofilm formation. Lead concentrations exceeded Health Canada Guidelines in some locations, with one public building showing levels 20 times above the recommended limits. Household practices including point-of-use treatment and water storage in containers were associated with decreased microbiological quality, particularly when using filtration devices. A novel application of photoelectrochemical chemical oxygen demand (peCOD) measurements showed promise as an indicator of water quality deterioration. This study highlights the challenges of maintaining safe drinking water in Arctic communities and emphasizes the need for improved infrastructure and monitoring strategies adapted to northern contexts.

Conventional wastewater treatment systems carry a significant environmental footprint, underscoring the urgent need for more sustainable alternatives. Microalgae-based wastewater treatment systems represent a promising and eco-friendly alternative, by enabling simultaneous wastewater treatment and biomass production. Various system configurations including waste stabilization ponds, photobioreactors, sequential batch reactors, biofilm reactors, column bubble systems, hybrid systems, and high-rate algal ponds, leverage photosynthesis and microalgae–bacteria symbiosis to effectively remove nutrients and organic matter. Photobioreactors provide enhanced control of environmental conditions and optimize biomass production, while sequential batch and biofilm reactors prioritize biomass growth. Column bubble systems utilize granular biomass for efficient treatment and high-rate algal ponds rely on the symbiosis of algae and bacteria to improve treatment efficiency. Raceway pond design is customized to meet specific operational requirements, with nutrient loading and microalgae species selections playing crucial role in determining biomass yield and nutrient uptake. High-rate algal ponds (HRAPs) are engineered systems to optimize and intensify the algal–bacterial symbiotic processes, providing a high-efficiency framework for nutrient removal and biomass production. Environmental conditions such as temperature, light intensity, and pH affect the growth and dominance of different microalgae species in open pond systems. This review critically synthesizes recent findings to identify operational gaps and facilitate scale-up and implementation of nature based solutions in current practices. It focuses on raceway pond systems, examining key parameters governing algal–bacteria symbiosis, biomass production, nutrient removal, and harvesting efficiency. Finally, it provides a comparative assessment with alternative microalgae cultivation technologies in terms of performance and sustainability.