Environmental Science: Water Research & Technology最新文献

Recurring consumer complaints of discoloured water indicate a key management challenge for drinking water distribution systems (DWDS). This research examines the causes by investigating and quantifying the impacts of hydraulic conditions on the transition of material between the bulk water and infrastructure surfaces. It is the first to acknowledge and differentiate between particulate accumulation and mobilisation due to the processes of sedimentation and cohesive layers and provide evidenced based operation and maintenance guidelines to improve discolouration management. With the range of physical, chemical and biological interactions within DWDS the specific processes enabling particles to remain on pipe surfaces are not investigated or quantified here with the focus on delivering evidence based practical support. Results from 8 independent week long trials incorporating 18 hydraulic profiles in a full sized and extensively monitored experimental pipe-loop with flow control precision of 0.002 m s⁻¹ and using discolouration material collected from multiple operational networks are presented. Reynolds number is proposed to best describe the limit of sedimentation as a measure of the turbulence forces that are balanced by the self-weight forces. Shear stress, that quantifies surface forces, is proposed to best describe mobilisation. For practical guidelines and uptake these can be converted to velocities. Sedimentation was found to dominate up to a Reynolds number of 15 100 (0.25 m s⁻¹, 0.21 N m⁻²); above this cohesive layers were dominant. This indicates discolouration risks from sedimentation, likely in the tertiary zones of a DWDS, may be mitigated if flows regularly attain these values. Material accumulated following sedimentation was shown to be effectively removed by a shear stress of 0.77 N m⁻² (0.5 m s⁻¹, Re 30 300), representing an idealised flushing value as forces above this showed negligible benefit on their removal. No effective upper flushing value was found in these trials for effective full mobilisation of cohesive layers.

Developing sustainable, metal-free catalysts for persulfate (PDS) activation is crucial for antibiotic removal in water environments. In this work, boron–sulfur–nitrogen co-doped biochar (BS4C) was synthesized via one-step pyrolysis of walnut shell, boric acid, and thiourea. The introduction of B, N, and S atoms synergistically modulated the electronic structure of carbon, creating abundant electron-deficient sites for PDS activation. As a result, BS4C exhibited excellent catalytic performance toward sulfadiazine (SDZ) degradation, achieving 83.8% removal within 60 min, and maintained strong resistance under the coexistence of various anions and natural organic matter. Radical quenching and EPR analyses confirmed that the process followed a ¹O₂-dominated non-radical oxidation pathway. These findings highlight the potential of biomass-derived, heteroatom-doped carbon materials as sustainable, metal-free catalysts for antibiotic degradation and water purification.

Residual flotation collectors are the most widespread organic pollutants in tailings wastewater, and their efficient abatement usually involves energy-consuming and high-cost treatments. In this study, the applicability of electrocoagulation for removing butyl xanthate (BX), a typical thiol collector for sulfide ore flotation, from wastewater was investigated. Chemical oxygen demand (COD) and turbidity variation were monitored to reveal the removal behavior of BX. The results showed that the efficiency of copper-based electrocoagulation was significantly higher than that of conventional aluminum or iron electrodes. More than 91.5% of COD was removed within 6 min of electrolysis operated at 6 mA cm⁻² with natural pH and 0.02 M Na₂SO₄ concentration. Calcite and copper electrocoagulation played a synergistic role in accelerating COD removal from the wastewater. Mechanism analysis indicated that the electrocoagulation process involved two successive stages. First stage: the transformation of BX into insoluble copper–organic complexes; second stage: the destabilization of the complex colloid by a charge neutralization mechanism. Calcite particles adsorbed a portion of the suspended complexes and acted as coarse particles that facilitated the settling of fine particles. The proposed simple electrocoagulation process could represent an effective strategy for removing BX and mitigating environmental pollutants discharged from the mineral processing industry.

This study validated a 1 L-capacity sulfate-reducing bacteria-based bioelectrochemical system (SRB-BES) for treating sewage wastewater in continuous mode over ∼66 days. Hydrogen production of ∼50% in the SRB-BES at 1032 hours of operation indicates that sewage wastewater can be a good renewable energy source if properly harnessed. With the increase in soluble ammonia, the average TOC, SO₄²⁻, and PO₄³⁻ removal efficiency of 56.76%, 47.04%, and 72.44%, respectively, was retained. An increase in pH from slightly acidic to alkaline and stabilization with the increasing sampling time results in more precipitation of toxic metal ions, causing the metal ion concentration in solution to decrease from 234.34 mg L⁻¹ to 217.98 mg L⁻¹ and 212.88 mg L⁻¹, observed at 4 and 8 hours of sampling, respectively. The sulfate reducer is enriched to 4.26%, 5.38%, and 5.60% in the bioanode, biocathode, and treated culture, respectively. Thermophilic Kosmotoga at the anode (4.94%) and cathode (3.48%) indicates the possible utilization of elemental sulfur as a terminal electron acceptor at the bioelectrodes. The improved H₂/CH₄ ratio from 0.55 to 4.94 indicated ∼10 times SRB population activity in a mature BES. This research supports the large-scale implementation of the SRB-BES, highlighting its efficacy in treating wastewater and contributing to resource recovery at the lowest operational cost.

Groundwater serves as the main source of drinking water, especially in rural India. The primary threats to human health and water quality are pollutants like nitrate and fluoride. To determine the concentration of fluoride and nitrate, as well as their geographical distribution and possible sources, the current study examined the hydrogeochemical properties of groundwater in the stone-mining regions of Kota, Rajasthan, India. In this study, multivariate statistics, health hazard assessment, and entropy water quality index (EWQI) determinations were also carried out. Around 84% of the samples had fluoride content above the threshold limit for drinking water (1.5 mg L⁻¹). Similarly, nitrate contents were 25.5% and 33.3% higher in pre-monsoon and post-monsoon, respectively, than the permissible limit for drinking water quality (45 mg L⁻¹). Considering the EWQI values, nearly 19.6% and 21.6% of the groundwater samples were poor and very poor, respectively; hence, they were unfit for drinking in the pre-monsoon season. In the post-monsoon period, rainfall-induced dilution exerted a significant positive influence on groundwater quality by reducing the concentration of dissolved contaminants. The average value of the hazard quotient (HQ) of fluoride through groundwater ingestion for adults (children) in the seasons before and after monsoon was 2.29 ± 0.31 (3.03 ± 0.41) and 2.19 ± 0.30 (2.89 ± 0.39), respectively; hence, they posed the risk of non-carcinogenic risk to people, which is a severe concern. In this study, elevated fluoride levels were found in the groundwater, likely due to the dissolution of fluoride-bearing minerals at higher temperatures and extended residence times, which encourages fluoride weathering in semi-arid regions. The findings of this study would be useful for managing groundwater resources strategically while preserving groundwater quality and reducing health hazards.

Disinfection of water by chlorine is of paramount importance to public health, while higher than regulated concentrations are toxicologically dangerous and must be controlled with great accuracy in real-time. In the present study, we introduce an ultra-green fluorimetric sensor based on carbon dots (C-dots), synthesized for the first time from waste mango endocarp, for the quantification of free chlorine. The biogenic C-dots synthesized show strong blue fluorescence that is selectively quenched by hypochlorite by an oxidation-mediated process. The structural and surface characteristics of the synthesized C-dots were extensively characterized using UV-vis spectroscopy, fluorescence spectroscopy, transmission electron microscopy (TEM), Fourier-transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), and dynamic light scattering analysis (DLS) to measure size and zeta potential. To render monitoring field-deployable, the system is applied using a low-cost, Arduino-powered portable device with a UV source and RGB sensor for real-time, reagent-free chlorine detection in pool water. The method has a wide range of linearity (0.01–100 ppm), good detection limit (3.0 ppb), and selectivity. The method's sustainability was confirmed through ComplexMoGAPI, BAGI, and RGB 12 tools. The present work synergistically combines food waste valorization, nanotechnology, and embedded systems into a smart, sustainable platform for water quality management.

Water scarcity and salinity pose acute challenges to sustainable development, requiring efficient, scalable and environmentally friendly water treatment technologies. Capacitive deionization (CDI) is emerging as a highly sustainable and energy-efficient water purification technology with notable advantages for brackish water desalination, wastewater treatment, and decentralized small-scale systems. The development of scalable and high-performance electrode materials is critical to accelerate the transition of CDI toward industrial and commercial adoption. Prussian blue (PB) and Prussian blue analogues (PBAs), with their open-framework crystalline structures, rapid and reversible ion-storage capabilities, and high theoretical capacitance, have recently gained attention as next-generation CDI electrode materials. Despite promising laboratory-scale results, key challenges including long-term electrode stability, large-scale synthesis, environmental compatibility, and reliable performance under real-water conditions remain unresolved. This review provides a comprehensive assessment of the recent advances in PB and PBA design, synthesis, and CDI performance, with a particular focus on their feasibility for industrial-scale manufacturing and deployment. Strategies such as multi-metallic analogues, hierarchical porous architectures, and hybrid composites with conductive materials are examined to enhance the desalination capacity, rate capability, and operational durability. Furthermore, critical barriers to commercialization including scalable and cost-effective synthesis, integration into modular pilot-scale systems, and performance in complex water matrices are discussed. Finally, this review offers techno-economic perspectives and practical insights to guide the development and industrial translation of PB-based CDI technologies, advancing sustainable and affordable clean-water solutions.

Herein, an eco-friendly GO-based composite membrane was successfully synthesized by integrating with ascorbic acid (AA). The crosslinking/bonding of GO and AA/GO composite membranes were evaluated using FT-IR technology. Surface morphology and cross-sectional investigations of the membranes were investigated by using scanning electron microscopy (SEM). The d-spacing of GO and AA/GO materials was measured using X-ray diffraction (XRD). The as-prepared membranes exhibit excellent permeability and rejection efficiency for numerous dyes and salts. The rejection efficiency and permeability of different dyes were measured as for rhodamine B (rejection 99.9% and permeance 180 ± 5 L m⁻² h⁻¹ bar⁻¹), for methylene blue (rejection 99.7% and permeance 245 ± 5 L m⁻² h⁻¹ bar⁻¹) and rose bengal (rejection 99.4% and permeance 270 ± 5 L m⁻² h⁻¹ bar⁻¹). In addition, the membrane showed good separation for NaCl (rejection 87.5% and permeance 335 ± 5 L m⁻² h⁻¹ bar⁻¹), Ni(NO₃)₂ (rejection 95.8% and permeance 255 ± 5 L m⁻² h⁻¹ bar⁻¹) and Pb(NO₃)₂ (rejection 98.9% and permeance 170 ± 5 L m⁻² h⁻¹ bar⁻¹). Furthermore, the as-prepared membranes are most stable in all three media up to 65 days. This approach highlights the potential practical applications of GO-based membranes in treating wastewater effluent from aqueous systems.

With passage of the CHIPS (Creating Helpful Incentives to Produce Semiconductors) and Science Act of 2022, growth of semiconductor facilities in the U.S. will increase, which will demand the need for treating industrial wastewater rich in xenobiotic compounds. One wastewater management option is disposal to municipal water resource recovery facilities (WRRFs). However, WRRFs are not conventionally designed for xenobiotics removal specifically associated with semiconductor facilities. Research herein interrogated the effects of reverse osmosis concentrate (ROC) derived from a water recycling system treating semiconductor wastewater on wastewater treatment. ROC impaired nitrification at the bench and eliminated nitrification at the pilot scale; impact at the pilot scale was almost immediate. Ammonia oxidizing bacteria were eliminated once ROC was added; also, no ammonia oxidizing archaea, Crenarchaeota, or comammox were detected. Bench-scale data suggested ROC might also impair biological phosphorus removal; more critically, pilot scale effluent phosphorus increased 570%, with the relative fraction of glycogen accumulating organisms increasing ∼7× with ROC addition. The proliferation of GAOs concurrent with ROC addition likely contributed to EBPR deterioration. At a molecular level, metabolomic data revealed key indicators of nitrification – fructose, 3-phosphoglyceric acid, and pyruvate – decreased with ROC addition. Moreover, the ROC-impacted metabolome exhibited the strongest correlations with amino acids. While no direct linkage between the amino acids and nitrification could be inferred, the predominance of these peptide building blocks combined with a significant loss of biomass suggests protein hydrolysis associated with bacterial die-off. Conversely, correlations without ROC were dominated by TCA cycle metabolites, indicating the predominance of oxidative reactions supporting energy production. Mitigating the effects of ROC is possible; research focused on the acute effects of ROC addition, and attenuation/dilution in the sanitary sewer collection system may mitigate toxicity. Ultimately, municipal WRRFs need to approach receiving semiconductor wastewater with caution and careful study.

Livestock and poultry wastewater is one of the main sources of antibiotic pollution, but compared with the high concentration of COD, turbidity and other pollution indicators, the changes of trace pollutant antibiotics are often ignored in the treatment of livestock and poultry wastewater. There are few studies on the removal efficiency of antibiotics and whether there is a change in substance structure during coagulation and precipitation as a commonly used livestock and poultry wastewater treatment process. The optimal removal conditions of tetracycline (TC) by flocculants FeCl₃, AlCl₃ and PAC were obtained by simulating the turbidity of actual livestock and poultry wastewater and providing a flocculant formation environment. Comparative analysis showed that FeCl₃ coagulant had the best adsorption efficiency for TC. The flocs formed by FeCl₃ coagulant adsorbed tetracycline to form dense particles, and the flocs of AlCl₃ and PAC coagulant formed a stacked network after adsorption. It is worth noting that the optimal efficiency may be caused by the change of reaction environment which is caused by the concentration ratio of coagulant aid (NaHCO₃) and coagulant, and TC is degraded by chemical reactions. In addition, not only adsorption in the process of removal of tetracycline by coagulation and precipitation, but also the morphological structure of tetracycline was changed which may be due to the oxidation of high-valence metal ions or the presence of hydroxyl metal ions and Cl⁻. This study found that in the traditional coagulation process with the main goal of removing turbidity and organic matter, the unexpected synergistic removal efficiency of trace antibiotic tetracycline is of great value. It can achieve the ‘multiple’ pollution control effect without changing the core process of the existing water treatment plant, which provides a scientific basis for reducing the environmental emission of antibiotics at low cost.