Environmental Science: Water Research & Technology最新文献

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.

The persistence of per- and polyfluoroalkyl substances (PFAS) in aquatic environments poses significant environmental and health risks, necessitating the development of effective and sustainable remediation strategies. This study evaluated the combined use of chitosan-modified biochar (Chi-BC) and ultraviolet advanced reduction processes (UV-ARP) for PFAS degradation, focusing on environmental influences and varying PFAS chemistries. Chi-BC effectively adsorbed and concentrated PFAS onto its surface, enhancing localized radical activity and enabling efficient defluorination. The Chi-BC/UV-ARP system achieved high degradation and defluorination rates, notably with long-chain PFAS, where adsorption facilitated radical access to C–F bonds. Environmental factors, including ionic strength, nitrate, and natural organic matter (NOM), impacted system efficiency by altering radical availability and PFAS interactions. Interestingly, nitrate enhanced PFAS adsorption onto Chi-BC, indirectly promoting defluorination, while NOM showed mixed effects depending on concentration. Overall, this work presented Chi-BC/UV-ARP as an energy-efficient PFAS treatment strategy, where Chi-BC's adsorption characteristics enabled the use of compact reactors and lower energy inputs, advancing practical applications for diverse water chemistries.

Ceramic membranes have emerged as a game-changing solution for oil–water separation, addressing important environmental and industrial concerns related to oily wastewater treatment. Ceramic membranes work by mechanisms such as straining, adsorption, and coalescence, with porosity, pore size distribution, and surface hydrophobicity all having a significant impact on their performance. Materials such as alumina (Al₂O₃), silicon carbide (SiC), and titanium dioxide (TiO₂) have exceptional chemical stability, heat resistance, and fouling resistance, making them suitable for demanding industrial conditions. Applications include industrial wastewater discharge, water recycling, and pre-treatment processes for desalination, demonstrating their versatility. The review assesses membrane performance parameters including flux, rejection rates, and long-term durability, while also evaluating issues such as fouling and high operational expenses. Surface engineering innovations, dynamic filtering modes, and self-cleaning technologies are being investigated as potential techniques to enhance efficiency and sustainability. Ceramic membranes have the potential to transform sustainable water treatment systems by combining advances in material science and engineering, providing long-term, efficient, and environmentally friendly solutions to global water concerns.

The leaching of nitrogen from agricultural fields into rivers substantially impacts the diversity, composition, and function of sediment microbial communities. However, how elevated nitrogen levels affect the assembly processes of these communities and, in turn, influence water quality remains lacking. This study decodes these causal pathways through a microcosm experiment that simulates nitrogen input using urea, focusing on the assembly mechanisms and the subsequent impact of the reassembled community on water quality. The results demonstrated that nitrogen input shifted the bacterial community assembly from stochastic to deterministic dominance (normalized stochasticity ratio <50%), forming a nested structure with a nestedness-resultant dissimilarity index of 0.02 (compared to 0.01 for the control), whereas fungi were less affected. The reassembled dominant bacterial community included anaerobic Bacillota and Bacteroidota. Mantel analysis revealed that Abditibacteriia, Fimbrifmonadia, and Desulfurellia were the core drivers of water quality changes and black-odorous substances. Structural equation modeling indicated that nitrogen input indirectly reduced dissolved oxygen levels (from 7.10 ± 0.01 mg L⁻¹ to 0.65 ± 0.05 mg L⁻¹) and increased chemical oxygen demand (from 4.81 ± 0.00 mg L⁻¹ to 159.45 ± 9.72 mg L⁻¹) and acid-volatile sulfide levels (from 169.22 ± 0.01 mg kg⁻¹ to 363.13 ± 7.30 mg kg⁻¹) by enriching Desulfurellia. Nitrogen input affected ammonium-nitrogen production (from 3.88 ± 0.03 mg L⁻¹ to 98.72 ± 3.93 mg L⁻¹) through direct chemical action and indirect biological action, while nitrate-nitrogen generation (from 1.55 ± 0.05 mg L⁻¹ to 15.35 ± 1.32 mg L⁻¹) was indirectly regulated by enriching Abditibacteriia, enhancing the potential for water self-purification. The findings of the study confirm that the reassembled microbial community driven by nitrogen input further regulated water quality, providing a theoretical basis for aquatic ecosystem restoration.

Water scarcity is an escalating global challenge driven by population growth and resource depletion. Conventional fresh water production methods typically require access to liquid water sources, limiting their applicability in remote or arid regions. Water-from-air technologies offer a potential solution but are often hindered by high energy demands and/or climatological conditions. This study introduces clathrate-based desalination of deliquescent salt solutions as a novel approach for atmospheric water harvesting, with potassium acetate selected as the model salt. Potassium acetate deliquesces at a relative humidity as low as 23.3%, producing a concentrated saline solution (17.8 wt% at 90% RH). By exploiting the clathrate creeping phenomenon, where hydrates grow along surfaces, enabling facilitated phase separation, 84% purification of this brine was achieved. Advanced architectures, further enhancing the crucial clathrate creeping potentially lead to further improvements of the obtained results. This process demonstrates the potential of an energy-efficient alternative to existing water-from-air technologies.

Trace levels of pharmaceuticals in sewage pose persistent environmental risks due to limited degradation in conventional wastewater treatment. This study addresses this by employing coconut shell-derived biochar (CBC) and its iron-modified variant (Fe-CBC) as activators of peroxymonosulfate (PMS) to degrade acetaminophen (ACP) in both aqueous and raw sewage matrices at low concentrations. Under optimized conditions (Fe-CBC: 500 mg L⁻¹; PMS: 400 mg L⁻¹), ACP removal exceeded 99% within 30 min, outperforming peroxydisulfate (PS) activation. Enhanced surface chemistry and iron sites in Fe-CBC substantially promoted reactive oxygen species (ROS) generation, particularly superoxide (O₂˙⁻) and singlet oxygen (¹O₂), which were confirmed via scavenging experiments to be dominant in driving ACP breakdown. The system maintained robust performance across a wide pH range (3–10) and demonstrated resilience against common inorganic ion interferents. Liquid chromatography mass spectroscopy (LC-MS) identification of degradation intermediates enabled the proposal of a mechanistic pathway. Importantly, Fe-CBC exhibited excellent regenerability over multiple reuse cycles, retaining high catalytic efficiency. In real sewage, the Fe-CBC/PMS combination significantly outperformed CBC/PMS in ACP removal and delivered strong biocidal effects, complete inhibition of E. coli, and evident structural damage to rotifers and nematodes after 90 min. Altogether, the Fe-CBC/PMS process shows strong promise as an integrated approach for simultaneous removal of trace pharmaceuticals and microbial contaminants from sewage.

In this work, a novel oxidation process combining nanoscale zero-valent iron (nZVI) and chlorine is reported for the efficient degradation of a model azo dye (CG-HG) in aqueous solutions. The originality of the process lies in the in situ generation of high-valent iron species (Fe(IV)) as the dominant selective oxidants, rather than classical hydroxyl or chlorine radicals. This provides enhanced selectivity and reduced susceptibility to common radical scavengers. Under optimized conditions (100 mg L⁻¹ nZVI, 250 μM chlorine), the system achieved >95% dye removal within 5 minutes, with a synergy index up to 14.43. Radical quenching experiments and mechanistic investigations confirmed Fe(IV) as the primary reactive species. The process remained effective across varying pollutant concentrations and demonstrated long-term durability with over 80% efficiency retained after 10 reuse cycles. The robustness of the system was further evaluated under realistic conditions, showing variable sensitivity to common inorganic ions (Cl⁻, SO₄²⁻, NO₃⁻, NO₂⁻, Br⁻), surfactants, and humic acids. Notably, Fe(IV)'s high reactivity with nitrite and bromide led to complete inhibition, while chloride and nitrate had minor effects. Unexpectedly, sulfate significantly suppressed performance at higher concentrations, likely due to oxygen salting-out, which reduced Fe(II) release. Finally, tests in natural mineral water, river water, treated wastewater effluent, and seawater demonstrated the system's practical relevance. While moderate salt content in mineral water enhanced dye removal, seawater imposed severe inhibition. Despite the strong primary degradation performance, the process achieved a moderate TOC removal of 38%, indicating the persistence of some by-products and the potential need for complementary post-treatments (e.g., biological processes) for full mineralization. These findings underline the importance of matrix composition and support the feasibility of the nZVI/chlorine process as a selective, rapid, and durable oxidation process for pollutant degradation in real water systems, especially, natural mineral water.

The aim of this paper was to examine the growth and mobilization behavior of early-stage biofilms in a pilot scale, controlled PVC drinking water system. An alternative method for biofilm growth used a concentrated solution of microorganisms sourced in tap water to inoculate the pipe system and allowed biofilms to be formed over a 28-day period. Biofilm development was also assisted with nutrient addition and disinfection depletion from the experimental system water. The pipe loop was then flushed to mobilize these biofilms. The growth and mobilization of the biofilms were assessed with molecular and fluorescence microscopy analysis of bulk water samples and removable pipe wall samples. Results showed that: (1) biofilms followed a rapid growth period on the pipe wall between 0 and 14 days, and 21 and 28 days; (2) biofilm growth was apparently halted between 14 and 21 days, likely because of a shift in bacterial community composition; (3) biofilms were observed to preferentially accumulate at the invert pipe position along the full longitudinal direction of the pipe but rapidly decreased for the springline and obvert circumferential positions of the pipe; (4) a flushing flow of 6.5 L s⁻¹ (1.2 Pa) was not able to fully remove the biofilms from the pipe wall; (5) biofilms were observed to form in clusters on the pipe wall which remained fully attached to the pipe wall even after flushing. Biofilms investigated here were likely impacted by the alternative growth method, but their physical structure still resembles biofilms from operational DWDSs. The research findings add to the emerging knowledge concerning the growth and mobilization of biofilms in drinking water systems. In addition, the alternative method to investigate biofilms is highly reproducible and can facilitate future studies in the field.