Environmental Science: Water Research & Technology最新文献

Lead (Pb²⁺) is one of the toxic pollutants that poses hazardous and severe risks to human health and the environment globally. Lead toxicity issues can be addressed primarily by the detection of Pb. Thus, the requirement for accurate sensors for lead detection in environmental samples is tremendously increasing across the globe. Fluorescence-based detection of lead in water samples can serve as a stepping stone towards achieving goals such as point-of-care, portable, and on-site detection. In the present study, a selective fluorometric chemical sensor developed from dithizone and carbon quantum dots (CQDs) embedded in chitosan polymer thin films was evaluated for Pb²⁺ detection in various natural water resources. The fluorescent chemical sensors were characterized using FTIR spectroscopy, XPS, XRD, TEM, CLSM, UV spectroscopy, and fluorescence spectroscopy. Pb²⁺ ions were detected employing a fiber optic spectrophotometer (FOS) paired with a reflectance probe. Two river water samples and household tap water samples were evaluated for the presence of Pb²⁺ ions, and spiking studies were carried out to measure the accuracy of detection. The sensing and analytical results indicated that lead detection with a limit of detection of 18.3 nM was possible in the 0–100 μM range of concentration with a response time of 1 minute. The spiking of Pb²⁺ concentration in the various water resources led to an accurate estimation with a maximum error of 1.4%, indicating an interference-free detection of Pb²⁺. The estimation of Pb²⁺ based on Micro-plasma Atomic Emission Spectroscopy was used as a reference method. The results indicate that the developed fluorescent chemical sensor based on dithizone-CQD-impregnated chitosan thin films coupled with a fiber optic spectrometer device shows tremendous potential for point-of-care and real-time monitoring of Pb²⁺ ions in real water samples.

A novel and highly efficient photocatalyst, g-C₃N₄/Bi₂MoO₆/clinoptilolite nanocomposite (CNBC), was synthesized by a hydrothermal method and acted as a Z-scheme heterojunction for efficient activation of peroxydisulfate (PDS) to degrade oxytetracycline (OTC) under visible light (vis) irradiation. The morphology and structure of the photocatalyst were determined by XRD, FT-IR, FE-SEM, EDX, BET, TGA, UV-vis DRS, PL, and XPS. The results showed that CNBC-30 had the best photocatalytic performance with an OTC removal efficiency of more than 87% within 120 min under the conditions of [OTC] = 20 mg L⁻¹, [catalyst] = 500 mg L⁻¹, [Na₂S₂O₈] = 1.26 mM, and pH = 4 at room temperature, which was much better than those of pure g-C₃N₄, Bi₂MoO₆, and CNB composites. This superiority is due to the excellent adsorption ability of clinoptilolite that effectively forms the g-C₃N₄/Bi₂MoO₆ heterojunctions, thus improving the ability to separate charge carriers while decreasing the recombination rate of electron–hole pairs. Furthermore, the effect of catalyst dosage, oxidant concentration, initial pollutant concentration, solution pH, and coexisting anions on the OTC degradation was comprehensively studied. The results showed that the CNBC-30/PDS system had high reusability and adaptability at different pH levels (3.0–11.0). Quenching tests showed that ¹O₂, O₂˙⁻, and h⁺ played the main roles in OTC degradation. In addition, OTC intermediates were identified and degradation pathways were proposed based on the results of MS analysis. DFT calculations successfully predicted the positions on the OTC molecule with high Fukui numbers that are suitable for attack by oxidants. CNBC-30 was stable for OTC degradation after four cycles with a degradation efficiency of above 78%, demonstrating its durability and potential for practical applications. This study provides insight into PDS activation in the visible light region by a clinoptilolite-based Z-scheme heterojunction for organic pollutant degradation.

This study reports a sustainable and green method for phosphorus (P) extraction and recovery from waste activated sludge (WAS) using glycine as a P-extraction agent. Glycine showed an extraordinary ability to induce P release from waste-activated sludge at a rate of 8.7 mg P per L per h without being consumed. The P-extraction rate was linearly related to the mixed liquor suspended solid concentration and was not affected by the temperature in the range of 25–35 °C. After extraction, the released P was recovered via calcium precipitation, resulting in high P-content (48%, as phosphate) products (dominated by amorphous calcium phosphate). An unparallel advantage of the method is the high recyclability of glycine. Repetitive experiments showed <10% glycine loss over four P-extraction–P-recovery–glycine-reuse cycles. Additionally, extremely low heavy metal contents were observed in the P-recovery products in comparison to the acid/alkali-assisted P extraction, indicating its environmental friendliness as a sustainable strategy for P recovery from WAS.

As non-sewered toilets are now the most commonly used sanitation facilities, the faecal sludge management (FSM) sector is starting to be recognised as an important actor for global carbon management. The development of systematic strategies to calculate avoided emissions and carbon storage opportunities is currently constrained by a lack of understanding of carbon flows during faecal sludge treatment. This study investigated carbon sequestration potential for faecal sludge treatment systems that involve co-pyrolysis of human faeces (HF) and wood biomass (WB) at different blending ratios HF : WB (100 : 0, 75 : 25, 50 : 50, 25 : 75, 0 : 100) and temperatures (450, 550, 650 °C). The systematic investigation of analytical biochar stability parameters and the quantification of carbon flows among pyrolysis products were carried out for the first time in the context of faecal sludge. The stability of the produced biochars was assessed based on their remaining volatility, carbon structure (H/C and O/C ratios, SEM and FTIR analyses) and oxidation resistance (chemical oxidation by H₂O₂ and thermal degradation by thermogravimetric analysis [R₅₀ index]). Overall, co-pyrolysis of HF and WB improved carbon fixation and biochar stability, enhancing carbon sequestration potential compared to pyrolysis of pure faecal feedstocks. Biochars produced from 50 : 50 HF : WB blends at 550 °C had the highest carbon retention (41.1%); this feedstock blending ratio corresponds to ∼30 g dry wood added in toilets as a cover material (per user per day), based on the expected daily excretion quantities. For these conditions, the H/C, O/C ratios, H₂O₂ oxidation and R₅₀ index values suggest that the produced biochars have developed an aromatic structure and are suitable for long-term carbon storage. The biochar characteristics were found to be more dependent on feedstock composition than pyrolysis temperature – provided that the temperature reached was sufficient to ensure completion of the main pyrolytic reactions (≥500 °C) – while carbon flows to the bio-oil and non-condensable gas fractions were significantly influenced by pyrolysis operational parameters (retention time and inert gas flow rate). The formation of CaCO₃ was observed via SEM/EDX and can be further investigated as a potential additional carbon storage mechanism in FSM. The findings of this research can be used to create a methodological dataset to inform carbon assessments and future modelling applications, paving the way towards the establishment of carbon-negative FSM.

This study examines the potential of Purolite Shallow Shell™ SSTA63 anion exchange resin for mitigating nitrate ion (NO₃⁻) contamination in aqueous environments. Through systematic experimentation, including dosage optimization, pH dependency, kinetic and desorption studies, we investigate the sorption behavior and practical applications of the resin. Results indicate that the resin effectively removes NO₃⁻ ions, with maximum efficiency achieved within 10 minutes. When 0.025 g of resin was used, 75% of NO₃⁻ was removed, whereas with 0.05 g, 89% was removed, and with 0.1 g of resin, 95% was removed. At pH 1, approximately 50% of NO₃⁻ ions were removed, with removal efficiency reaching 97% between pH 4 and 10. Sorption isotherms affirm the suitability of the Langmuir model for the current investigation. The monolayer maximum sorption capacity (q_max) value was found to be 53.65 mg g⁻¹. The resin demonstrates robust desorption capabilities using 0.1 M hydrochloric acid (HCl), effectively desorbing NO₃⁻ above 99%, indicating easy NO₃⁻ desorption and resin regeneration. The presence of coexisting ions such as chloride (Cl⁻), sulfate (SO₄²⁻), and phosphate (PO₄³⁻) showed a minimal impact on NO₃⁻ removal in individual binary mixtures, with efficiencies exceeding 93%, suggesting a strong selectivity of the resin towards NO₃⁻. Purolite SSTA63 anion exchange resin exhibited a high affinity for NO₃⁻ ions, even over other competing ions, despite the general trend of ion exchange resins to favor ions with a higher atomic number and valence. Overall, this resin presents a promising solution for NO₃⁻ removal, with implications for water treatment and environmental remediation.

This study investigates the effect of ferrous sulfate (FeSO₄) treatment on protective film formation and subsequent microbially influenced corrosion (MIC) of CuNi 70/30 pipeline alloy, a material commonly used in maritime platforms. CuNi 70/30 coupons were treated with FeSO₄ solution in potable water and seawater simulating a flow speed of 0.94 m s⁻¹ for 5 d. The treated coupons exhibited a protective iron oxyhydroxide, likely lepidocrocite (γ FeOOH), film on the surface. MIC performance was evaluated in modified Baar's medium with SRB for 28 d. Results revealed thicker SRB biofilm and increased MIC pitting attack on FeSO₄ treated coupons compared to untreated coupons. These findings suggest that FeSO₄ treatment may exacerbate MIC susceptibility in MIC-prone environments, highlighting the importance of carefully considering corrosion mitigation strategies in maritime platform applications.

In this study, a hybrid bionanomaterial (GO@Di) composed of Dictyosphaerium sp. microalgae and graphene oxide (GO) was synthesized for the first time to be used as an adsorbent for the removal of pentavalent arsenic (As(V)) from aqueous solutions. GO@Di was characterized by analytical techniques including Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), pH at point of zero charge (pH_PZC), and BET surface analysis. Solution pH, adsorbent mass, initial concentration of the pollutant, and ionic strength were evaluated and optimized to identify the best conditions for As(V) removal using GO@Di. A removal efficiency of 69% and an adsorption capacity of 885 mg g⁻¹ were obtained under the optimal conditions of pH 3, 1 mg of GO@Di and initial As(V) concentration of 50 mg L⁻¹. The adsorption kinetics were also analyzed, reaching the equilibrium at 120 min. The experimental kinetic results were correlated with the pseudo-second order model. Equilibrium data were fitted with the Brunauer–Emmett–Teller (BET) isotherm model. Regeneration studies indicated that GO@Di could be re-used efficiently up to 4 adsorption/desorption cycles. Finally, GO@Di was applied to real samples of natural waters and industrial effluents, obtaining removal percentages between 52 and 95%, which demonstrated the promising potential of GO@Di to depollute complex aqueous matrices containing As(V). Future studies will focus on the removal of other arsenical species using GO@Di and its implementation in dynamic adsorption systems.

The objective of this study was to assess the impacts of biochar and iron-enhanced sand (IES) on the comprehensive contaminant retention performance of a field-scale stormwater filtration system. The system distributed runoff from a parking lot into three filters containing sand, sand amended with biochar (custom-produced via pyrolysis of red pine wood chips at 550 °C), or IES. Over the first two field seasons of operation flow into the testbed and out of each filter were continuously monitored, and influent and effluent samples were collected during 21 precipitation events and analyzed for various contaminants and water quality parameters. To account for variations in flow distribution between the filters, long-term filter performance was assessed based on comparison of apparent cumulative input and output contaminant loads over the study duration (i.e., apparent cumulative contaminant retention). The IES filter showed the most effective phosphorous retention performance (>90% net retention of total phosphorus, TP), reflecting results from previous studies. The biochar-amended filter showed improved retention of zinc and total inorganic nitrogen (TIN) relative to the sand filter, which may be attributed to: (i) enhanced electrostatic interactions between zinc and oxygen-containing functional groups on the biochar surface, and (ii) improved attenuation of ammonia-N due to reduced nitrification and/or enhanced adsorption of ammonium. The biochar-amended filter did not show improved retention of total organic carbon or Escherichia coli, in contrast to some previous studies, potentially due to differences in biochar material properties (e.g., reduced hydrophobic interactions due to the custom biochar's relatively polar surface chemistry) or operational conditions (e.g., differences in flow rate or biofilm development between the filters). These findings demonstrate the complexities surrounding the application of biochar as a stormwater filter material for broad contaminant removal, and warrant the development of best practice recommendations for biochar selection and performance testing.

Wastewater-based epidemiology can track infectious diseases and COVID-19 surges. There is variability in viral signals from wastewater owing to numerous sample processing and virus detection methods, and many factors including characteristics of wastewater treatment plants (WWTPs) should be considered to consistently associate the signals with COVID-19 prevalence. This study optimized the virus detection method, validated the use of a process-control virus, investigated 22 WWTPs across South Korea (covering approximately 20% of the population) during two periods (24.8 versus 2027.4 weekly COVID-19 cases per 100 000 people), tested the infectivity of SARS-CoV-2 in wastewater, and characterized the environmental factors influencing wastewater-bound SARS-CoV-2 and local COVID-19 using data-driven models (DDMs). The most sensitive virus quantification methods were selected (PEG precipitation and commercial kits for RT-qPCR detection, approximately 39% more sensitive) by comparing various methods. Using a surrogate virus showed reduced variation (approximately 24%) between the intra- and inter-laboratory results. The number of WWTPs with positive detection of SARS-CoV-2 in raw wastewater increased (four to twenty) as the national COVID-19 cases peaked. SARS-CoV-2 is more likely to be detected in moderately sized facilities located in populated areas with sanitary sewer systems. In addition, results of infectivity testing suggested no potential for COVID-19 transmission through wastewater. The DDMs indicated that the air temperature, water quality, and number of COVID-19 cases were related to the SARS-CoV-2 in wastewater. Community COVID-19 cases were predicted (test performance: 0.703–0.970) with the data on wastewater viral load and other variables implying that these factors should be monitored for wastewater surveillance.

Urban domestic wastewater is a significant source of dissolved organic matter (DOM) in aquatic environments, critically impacting urban water quality. This study integrates the optical properties and molecular features of DOM, providing a comprehensive understanding of its behavior in urban sanitary sewage. Utilizing ultraviolet-visible (UV-vis) spectroscopy, three-dimensional synchronous fluorescence spectroscopy, and ultra-high-performance liquid chromatography coupled with quadrupole time-of-flight mass spectrometry (UPLC-Q-TOF-MS), we establish a robust bidirectional correlation between optical properties and molecular characteristics. Our findings reveal that urban domestic wastewater is predominantly composed of protein-like substances and microbial humic components, rich in heteroatoms and homologous compounds. The established correlations between optical and molecular features validate the DOM characterization system, demonstrating consistency between photochemical properties and molecular characteristics. Molecules related to photochemical parameters align with high H/C and low O/C ratio regions. The correlation analysis indicates that the highly associated areas are the fluorescent domains of protein-like materials and microbially derived humic-like substances. This innovative approach provides actionable insights for urban water quality management, highlighting the critical role of these methods in effective environmental monitoring.