Environmental Science: Water Research & Technology最新文献

The relentless pace of industrial growth, as a direct result of the population boom, has consistently spawned consequential and often unmanageable issues, such as the pervasive problem of the release of toxic heavy metals into water. Among today's most critical environmental issues, heavy metal pollution has emerged as a severe problem. The predominant characteristic of heavy metals is their toxicity, exceptional solubility in aquatic environments, and the persistence of their ions without biodegradation, which causes specific issues regarding their potential accumulation within the human body through the food chain. The exposure of people and the environment to these toxic metals results in severe health problems. Additionally, reusing treated wastewater is the only solution for producing extra fresh water. The elimination of heavy metal ions from wastewater is crucial to uphold a clean environment and well-being of the people. A diverse array of approaches has been devised and put into practice for the treatment of wastewater, aiming to reduce heavy metal concentrations. These technologies cover membrane filtration, flotation, coagulation and flocculation, chemical precipitation, electrochemical processes, ion exchange, advanced oxidation processes (AOPs), and adsorption. Within this review, we present a detailed examination of important solution techniques that are necessary for discerning, workable and easily implementable wastewater treatment solutions for the elimination of heavy metals, thorough analysis of these methodologies, their mechanisms, their sustainability and their overall efficiency. Additionally, this review delves into the latest advancements and describes an array of approaches utilized for the elimination of heavy metals from wastewater by giving examples of pilot-scale processes used in some cases. It offers an insightful look into the ongoing commitments and technological breakthroughs that strive for more effective heavy metal removal and resource recovery from industrial wastewater. This review also examines various drawbacks and constraints in implementing these methods.

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Microbial electrolysis cells (MECs) are emerging as promising technologies for coupling wastewater treatment with renewable hydrogen production, but their efficiency hinges on electrode design. This review synthesizes 41 studies covering 55 electrode combinations, revealing how electrode composition and surface characteristics shape performance. Carbon-based anodes such as graphite felt and carbon cloth achieved chemical oxygen demand (COD) removal up to 95% and hydrogen production rates (HPR) between 0.1 and 45 m³ of H₂ per m³ of reactor per day. Metal-based cathodes, particularly stainless steel (SS304), yielded HPR values of up to 314 ± 17 m³ of H₂ per m³ of reactor per day with COD removal of 79 ± 4%. Modified electrodes incorporating nanoparticles and polymers further enhanced outcomes: Ni–Co–P coatings increased HPR nearly fivefold over bare metals, polymer-modified carbon felts doubled hydrogen yields and raised COD removal from 25% to >55%, and Cu/Ni nanocomposites achieved current densities of 226 A m⁻² with COD removal above 75%. These results demonstrate that modified electrodes can rival platinum-based benchmarks at fabrication costs reduced by up to 50%. Despite these advances, significant challenges remain. Most studies employ simple substrates such as acetate, leaving performance under real wastewater conditions poorly understood. Key operational factors, including electrode spacing, microbial community engineering, and suppression of hydrogen-consuming pathways, are inconsistently addressed, and the long-term durability of non-noble metal cathodes under corrosive conditions is inadequately characterized. Looking forward, polymer–nanocomposite hybrids and three-dimensional electrode architectures represent promising innovations, combining high conductivity, biocompatibility, and surface area at lower cost. These strategies have already achieved COD removal above 80% and hydrogen yields approaching platinum controls, highlighting their potential to drive MECs toward scalable, cost-effective deployment in sustainable wastewater treatment and renewable energy production.

Phenylurea herbicides (PUHs) represent one of the most extensively used herbicide families in agriculture worldwide. While effective for weed control, their environmental persistence, bioaccumulation potential, and formation of toxic metabolites raise significant environmental concerns. This review examines current electrochemical strategies for degrading phenylurea herbicides, with special emphasis on electrochemical oxidation (EC), photoelectrochemical processes (PEC), electro-Fenton (ECF) and photo-electro-Fenton (PECF), with particular attention to the various reactor configurations and their operational mechanisms. A critical innovation of this review lies in its systematic parameter assessment framework, which categorizes nine key operational parameters across all electrochemical degradation methods: electrode material, catalyst type, cell configuration, radiation source, operating conditions (pH, current density, temperature), removal efficiency, mineralization rate, degradation kinetics, identified intermediates, and energy consumption. For each technique, we highlight which parameters are essential, important, critical, or non-applicable, providing a structured framework to guide future experimental design. Selected case studies are presented to illustrate practical applications and performance outcomes. The review concludes with a critical analysis of current knowledge gaps and future research avenues that could enhance the sustainability, efficiency, and scalability of electrochemical remediation technologies. This work is intended as a comprehensive resource for environmental chemists, analytical scientists, and remediation engineers committed to addressing phenylurea herbicide contamination.

The present study evaluated the environmental and economic sustainability of an electrocoagulation-based system for arsenic and fluoride removal through life cycle analysis (LCA) and techno-economic assessment (TEA). The impact of different treatment capacities of the EC process has been evaluated. With the increase in scaling up the EC system from lab-scale (1.7 L) to large-scale (650 L), a reduction in environmental footprints across all ReCiPe midpoint categories (e.g. global warming potential (GWP) 5.38 to 2.63 kg CO₂ eq. (51%)) has been observed. Further, endpoint analysis indicated significant damage to the ecosystem (9.3 × 10⁻⁹ species per year) and resources ($0116). Interestingly, the negative endpoint human health impact values (−7.3 × 10⁻⁶ disability adjusted life years (DALY) for large-scale operation) suggest potential health benefits from treated water. Sensitivity and Monte Carlo analyses confirmed the robustness and reliability of the results, while utilizing carbon free electricity sources further reduced the impacts (GWP 36.7% less for solar). TEA analysis confirms the profitability of the EC treatment process since the net present value (NPV), internal rate of return (IRR), payback period (PB) and profitability index (PI) of the best scenario (3 shift operation with sludge utilization) are as INR 450.7 Lakhs ($0.51 million), 49.3%, 2.17 years and 1.85, respectively. Utilizing solar energy increases the capital expenditure (CAPEX) of the process by 64.2% but reduces the operational expenditure (OPEX) by 11.4%. Despite the higher initial investment for the use of solar energy, the overall scenario remains economically profitable. Overall, the integration of LCA and TEA highlights the feasibility of scaling up the electrocoagulation process as a sustainable and cost-effective solution for real-world applications.

Sedimental galena (PbS) is an important sink for lead in natural waters. Resuspension of PbS caused by storm disturbance can lead to its oxidative dissolution, resulting in higher ecological risks. Surface runoff resulting from intensive storms can also carry phosphate into receiving water bodies. It is hypothesized that phosphate from surface runoff can regulate Pb concentration and speciation during storm events. To test the hypothesis, the dissolution and transformation of PbS were investigated in the absence and presence of orthophosphate under different pH (5–8) and dissolved oxygen (0–8.4 mg L⁻¹) conditions to simulate the behaviors of suspended PbS. The results indicated that the kinetics of PbS dissolution was mainly controlled by pH while dissolved oxygen played a minor role when orthophosphate was absent. In the presence of orthophosphate (0.5 mg-P L⁻¹), the soluble lead concentration as high as 990 ppb resulting from PbS dissolution decreased immediately to ND (<5.1 μg L⁻¹), except at pH 5, due to the formation of pyromorphite. A saturation index (SI) greater than 16.16 was required to initiate pyromorphite precipitation. The results suggested that phosphate, which is often associated with eutrophication, could sequester soluble lead and reduce associated ecological risks resulting from sedimental PbS dissolution in storm events.

Per- and polyfluoroalkyl substances (PFAS) constitute a diverse class of highly stable synthetic organofluorines increasingly recognized for their environmental persistence, bioaccumulative behavior, and toxicological significance. It is especially concerning that they are frequently found in environmental matrices such as soil, groundwater, surface water, and biota globally. The impact is expected to be more severe in regions such as the Middle East and North Africa (MENA), where climatic conditions and water scarcity amplify the impact of even trace-level contamination. Groundwater, a critical resource in these regions, is especially vulnerable to PFAS infiltration from industrial effluents, landfill leachates, and aqueous film-forming foams (AFFFs). These unique pressures underscore the urgent need for a comprehensive assessment of PFAS in water systems across the Arabian Gulf and other arid regions. The review highlights several key insights. While PFAS have been detected in water systems across the region, available monitoring studies are limited compared to other parts of the world. In addition, regulatory frameworks for PFAS remain nonexistent, while international regulatory agencies such as the U.S. EPA and ECHA have established frameworks for legacy PFAS like PFOA and PFOS. On the analytical side, sample collection, preparation, and preservation are critical challenges due to the broad spectrum of PFAS chemistries and complex matrices. In addition, established analytical methods such as LC–MS/MS face barriers related to infrastructure cost and technical expertise. Concerning treatment technologies, conventional treatment methods have proven largely ineffective, with advanced methods like ion exchange resins and other sorption techniques leading the current research and large-scale treatment landscape. Overall, a regionally tailored, multidisciplinary approach is imperative to mitigate PFAS risks. Given the region's high per capita industrial footprint, extreme climatic conditions, and water insecurity, a significant pollution burden is anticipated, and extensive monitoring campaigns are recommended.

Microplastics (MPs) are emerging contaminants of concern due to their ubiquitous presence in aquatic environments and their ability to adsorb and transport other contaminants. In this study, the presence of MPs was determined in river water samples, reflecting their potential impact on the transport of other emerging contaminants in aqueous matrices. This study investigates the adsorption behavior of atrazine (ATZ), a widely used herbicide, onto pristine and UV-aged polyethylene (PE) and polypropylene (PP) MPs. The study revealed that UV aging enhances adsorption by increasing surface roughness and oxygen-containing functional groups. Batch adsorption experiments were conducted under varying environmental conditions, including pH, salinity, and dissolved organic matter changes. Adsorption kinetics were evaluated using pseudo-first-order, pseudo-second-order, and intraparticle diffusion models, with PSO providing a better fit, as indicated by lower p-values and higher R² values. The interparticle diffusion model showed that during the first stage of adsorption, surface adsorption was dominant, while pore diffusion was predominant at later stages. Desorption experiments indicated that aged MPs retain ATZ more effectively, reducing its potential for remobilization in aquatic systems. These findings provide insight into the environmental risks associated with MPs as carriers of pesticides and their implications for water quality and ecosystem health.

Thermal treatment of biosolids is receiving significant attention in the water industry as an alternative management option to land application. Traditional thermal treatment processes for biosolids management include drying and incineration, whereas emerging thermal technologies comprise dry thermal processes, such as pyrolysis and gasification, and wet thermal processes, such as hydrothermal carbonisation/liquefaction and supercritical water gasification. Thermal treatment is considered an efficient approach for the volume reduction of biosolids, contaminant destruction, and valuable product generation. However, there is a clear gap in the literature in benchmarking the range of available technologies, considering their techno-economic viability, emission potential, resource (energy and nutrient) recovery, and contaminant reduction. This knowledge is crucial for understanding the techno-commercial readiness, integration flexibility, and potential adoption of the thermal treatment technologies for biosolids management in wastewater treatment facilities. This critical review provides a comprehensive comparison of the various thermal treatment processes based on the parameters such as fate of nutrients and emerging contaminants, emissions, energy requirement, capital and operating expenditures, and scale-up maturity. It was found that dry thermal processes have substantial benefits over traditional incineration technologies, with pyrolysis and gasification being more energy-efficient and providing opportunities to generate valuable products (biochar and bioenergy). Hydrothermal liquefaction offers further benefits with high bio-oil and nutrient recovery and strong synergies with the existing water treatment infrastructures. Gasification and pyrolysis have high technology- and commercial-readiness level for biosolids treatment, making them suitable for the wastewater treatment industry. However, to ensure efficient and sustainable management of biosolids through thermal processes, there are some techno-commercial challenges, which are highlighted as future research perspectives.

This study investigates how biofilms influence the accumulation and mobilization of iron oxide particles in drinking water distribution systems (DWDSs). Two experiments were conducted in a full-scale PVC pipe loop: one with biofilms grown over 28 days and one without biofilms. Iron oxide particles were injected into the pipes under steady flow conditions to promote particle attachment to the pipe walls, followed by four sequential flushing steps designed to mobilize the attached particles. Particle accumulation and mobilization were assessed using suspended sediment concentration (SSC), turbidity, and microscopy. Biofilms increased particle attachment from 66% to 72% and enhanced particle retention during flushing. In the first flush, 79% of the mobilized mass was released in the no-biofilm loop compared to 69% in the biofilm loop, indicating stronger adhesion in the presence of biofilms. Subsequent flushes mobilized more material from the biofilm experiment, particularly under higher shear stress. Microscopy revealed that biofilms captured both fine and large particles (up to 30 μm), and even with limited surface coverage (∼3%), substantially enhanced particle adhesion. While the biofilms developed under experimental conditions may differ from mature biofilms in actual DWDSs, the results demonstrate that biofilms have the potential to promote particle accumulation and resist their mobilization under high-shear events. Despite the ubiquity of biofilms in DWDS, these results may help water utilities improve pipe cleaning strategies and better manage material accumulation within the systems.