Environmental Science: Water Research & Technology最新文献

Globally, Cryptosporidium continues to pose a significant health and economic burden despite significant efforts to develop effective on-site biosecurity and best management practices. According to the Global Burden of Disease Study (2016), this parasitic protozoan is responsible for more than 48 thousand deaths in children under the age of five and 7.2 million disability-adjusted life-years worldwide. Additionally, most Cryptosporidium species (e.g., Cryptosporidium hominis, Cryptosporidium parvum, etc.) are resistant to the majority of common disinfectants and can survive outside the body for extended periods. Consequently, it is crucial to establish a prompt and accurate diagnosis as well as the severity of the disease to prevent the spread of parasites and to enable effective management strategies. USEPA Method 1623 is currently used in centralized laboratories to perform routine diagnostic tests for this parasite. This process is laborious, expensive, and time-consuming. In the past ten years, a multitude of techniques based on conventional molecular biology techniques, such as polymerase chain reaction (PCR), nested-PCR, loop-mediated isothermal amplification (LAMP), recombinase polymerase amplification (RPA), and nucleic acid sequence-based amplification, have been utilized to analyze Cryptosporidium species. Similarly, several biosensing techniques have been developed in recent years, including electrochemical biosensors and the CRISPR-Cas system in lateral flow assays. This review discusses the most frequently employed techniques for isolating, quantifying, and genotyping Cryptosporidium species, and their implication on the diagnostic landscape. A subsequent evaluation of the most significant technical and biological challenges and limitations of these techniques is also undertaken.

Fluorescence spectroscopy holds promise as a rapid tracer of performance in decentralized wastewater treatment systems (DEWATS) that may reduce the monitoring burden on communities. In this study, we examined changes in chemical oxygen demand (COD), fluorescence-based indices, and parallel factor analysis (PARAFAC) modeled components under normal operation and during periods of disturbance at the time of scum removal in real decentralized treatment settings and in laboratory simulated wastewater treatment with an anaerobic baffled reactor (ABR). Amino acid-like peaks T and B and PARAFAC component C2 (with excitation/emission peak at 281/335 nm) decreased from influent to effluent due to preferential degradation of labile organic compounds, and the C2 decrease was significantly correlated (p < 0.01) with COD removal. The humification index (HIX) increased by ∼190% on average from influent to effluent during normal operation of all of the anaerobic and aerobic DEWATS evaluated in this study, further supporting the preferential removal of labile constituents during treatment. Meanwhile, a newly identified component, C3, with excitation between 410 and 420 nm and emission at 470 nm, increased under normal operation and may represent the formation of coenzyme 420 during biodegradation. Disturbance during scum removal disrupted preferential removal of peak T and resulted in a much lower change in HIX (only 24% increase) from influent to effluent. Recirculation of effluent into the influent stream was found to greatly reduce scum formation in lab-based ABRs while still maintaining a high removal of COD and peak T and producing substantial increase in HIX. The fluorescence-based indices were found to be robust indicators for tracking performance issues in DEWATS.

Wastewater treatment plants (WWTPs) are indispensable facilities that play a pivotal role in safeguarding public health, protecting the environment, and supporting economic development by efficiently treating and managing wastewater. Accurate anomaly detection in WWTPs is crucial to ensure their continuous and efficient operation, safeguard the final treated water quality, and prevent shutdowns. This paper introduces a data-driven anomaly detection approach to monitor WWTPs by merging the capabilities of principal component analysis (PCA) for dimensionality reduction and feature extraction with the Kolmogorov–Smirnov (KS)-based scheme. No labeling is required when using this anomaly detection approach, and it utilizes the nonparametric KS test, making it a flexible and practical choice for monitoring WWTPs. Data from the COST benchmark simulation model (BSM1) is employed to validate the effectiveness of the investigated methods. Different sensor faults, including bias, intermittent, and aging faults, are considered in this study to evaluate the proposed fault detection scheme. Various types of faults, including bias, drift, intermittent, freezing, and precision degradation faults, have been simulated to assess the detection performance of the proposed approach. The results demonstrate that the proposed approach outperforms traditional PCA-based techniques.

Electron sources for bacterial cell processes are diverse and include water (in phototrophs) and organic (in organotrophs) and inorganic compounds (in lithotrophs). All of them share the characteristic of having a low enough oxidation–reduction potential to allow cell energy gaining when coupled to typical cell electron acceptors. While most metals and alloys have a potential low enough to serve as electron donors for bacteria, data about their direct microbial oxidation are very limited. In this work, we show that magnesium, a metal with the lowest reduction potential in the galvanic series, cannot be oxidized directly by denitrifying bacterial cells, but can serve as an electron donor when galvanically connected to them through graphite. We recognize this as a new way of accessing metal electrons for bacteria which, owing to the requirement of galvanic coupling, we propose to identify as galvanic lithotrophy. We exemplify the impact that this process may have, by showing its application to simultaneously remove nitrate, ammonium and phosphate from water, by using a readily scalable approach that allows us to recover these nutrients, in which an energy input is not required.

Optimized and efficient zinc chloride (ZnCl₂)-based chemical activation of rice straw yielded highly mesoporous carbons with an exceptional ability to adsorb the antibiotic amoxicillin (AMX). The maximum AMX adsorption capacity was found to be as high as 1308 mg g⁻¹. Greater understanding of the pyrolysis process was gained through TGA-IR, demonstrating that ZnCl₂ activation could reduce carbonization temperature, inhibit tar formation, and lead to the extensive release of oxygen-containing compounds during the dehydration processes in pyrolysis. In addition, a 2-step strategy for rice straw carbonization activated by ZnCl₂ is proposed, involving biomass (cellulose, hemicellulose, and lignin) decomposition at low temperature and subsequent dehydration at a higher temperature to obtain more graphitic mesoporous carbon. The optimum ratio of rice straw to ZnCl₂ was 1 : 2 (ZAC1:2); X-ray diffraction and X-ray photoelectron spectroscopic analysis confirmed the occurrence of graphitic carbon and revealed the existence of ZnO within the carbon structure. This, in combination with a significant surface area of 941 m² g⁻¹, large pore volume, and 100% mesoporosity with a narrow pore size distribution of 2–6 nm, significantly enhanced AMX adsorption. The Langmuir adsorption isotherm model revealed homogeneous adsorption, while kinetic studies revealed a fit to the pseudo-second order kinetic model. These highlight the significant potential of mesoporous ZnCl₂-activated rice straw carbon for application in wastewater treatment and in the remediation of emerging pollutants such as antibiotics.

Autotrophic anaerobic ammonium oxidation coupled to Fe(III) reduction (Feammox) is a potential technology for removing ammonium from low-C/N wastewater, but it requires a continuous supply of Fe(III) source. To reduce the supply, a microbial electrolysis cell (MEC) was employed to allow iron recycling in Feammox under different voltages (0.2 V, 0.6 V, and 1.0 V). Results showed that the optimal voltage was 0.6 V, with a maximum efficiency for ammonium oxidation of 71%. The ammonium oxidation rate achieved 2.5 ± 0.1 mg N L⁻¹ per day, which was 3 times that of conventional Feammox. Cyclic voltammetry confirmed that ammonium oxidation and iron redox occurred on the anode. The bacterial population had a unique evolutionary direction at 0.6 V, with Geobacteraceae becoming the dominant family. Positive interactions between nitrogen-related bacteria and iron-related bacteria enhanced the autotrophic Feammox process. This study will further advance Feammox in the treatment of ammonium-containing wastewater.

The use of hydrazine in various industrial sectors, especially as a synthetic precursor in pharmaceuticals, coating material for water boilers, and rocket propellant, is increasing globally. Hydrazine is known for its severe toxicity to human health and environmental pollution due to its lower biodegradability and bio-accumulative and toxic nature. The hazardous effect of hydrazine on human health and the ecosystem needs to be urgently addressed. The present study demonstrates the development of a thin film chemical sensor based on 2,4 dinitro-1-chlorobenzene (DNCB) and carbon quantum dots (made from phthalic acid and tri-ethylene diamine (TED)) co-immobilized in chitosan-based thin films for the specific detection of hydrazine. A portable fibre optic spectrometer (FOS) coupled with a reflectance probe was used to sense hydrazine molecules in different water resources such as household water supply and two river water samples. The developed chemical sensor thin films were characterized using various techniques such as XRD, FTIR XPS, TEM, UV spectroscopy, CLSM and fluorescence spectroscopy. The sensing results indicated an estimation of hydrazine in a minimal response time of 1 minute, limit of detection (LOD) of 7 ppb and linear range of 0–100 μM. The results also show high specificity and negligible interference against many probable interfering molecules. The spiked concentrations of hydrazine in various real water samples resulted in an accurate prediction near 100% with a minimal error of 1.2%. The photo-stability of the sensor films was found to be about 120 days. The developed sensor was validated against the HPLC method. The study clearly shows the excellent potential of the developed chemical sensors as a point-of-care tool for the real-time and specific detection of hydrazine in various water matrices using a fiber optic device system.

In this study, the conducting polymer poly(3,4-ethylenedioxythiophene) (PEDOT) was successfully polymerised through electrochemical (E-PEDOT) and chemical oxidative (C-PEDOT) polymerisation techniques. The photocatalytic reaction mechanism of PEDOT in removing aqueous contaminants, including hexazinone and methylene blue, was investigated with and without the use of Fe(III). An increase in iron concentration during PEDOT irradiation resulted in enhanced degradation of the contaminants. Moreover, E-PEDOT showed up to ∼90% removal of contaminants by a combination of adsorption and photocatalysis effects. Hydroxyl radicals played a critical role in the photocatalytic degradation of contaminants using PEDOT, in the presence and absence of iron. This mechanism was proved through coumarin degradation. When evaluating reusability, E-PEDOT showed a decrease in its adsorption behaviour but a consistent photocatalytic activity. Finally, it was revealed that the addition of iron externally or during chemical polymerisation could boost PEDOT performance. Therefore, it is worth considering the implementation of the UV/Fe(III)/PEDOT system, exhibiting remarkable efficacy in eliminating organic contaminants from aqueous solutions.

New orange peel biochar/clay/titania nanocomposites (NCs) were studied for photocatalytic degradation of tetracycline (TET) under both UV and natural solar irradiation by variation of NC dose, initial TET concentration, ionic strength, and competing anions. Total organic carbon (TOC) reduction was used to assess mineralization. Intermediate product formation during TET degradation was characterized using liquid chromatography-mass spectrometry and agar-based diffusion assays. The as-synthesized material prepared with biochar obtained at 600 °C (C600KT) exhibits the best TET degradation performance under UV light exposure and solar irradiation with up to 92 and 89% after 2 h, respectively. Especially under UV exposure, C600KT exhibits the highest apparent rate constant of 2.9 × 10⁻² min⁻¹ and a half-life of 23.9 min. About 60 and 50% TOC are removed after 2 h under UV and solar irradiation, respectively. Quenching experiments confirm that superoxide and hydroxyl radicals are the major reactive species involved in the degradation process. Furthermore, the treated effluents are harmless to both Escherichia coli and Staphylococcus xylosus, indicating that no intermediate products with higher toxicity are produced during the photocatalytic degradation. Additionally, the results show that the main fraction of TET is degraded within the first 15 min of irradiation. The C600KT composite is recyclable and retains its performance over at least four cycles, proving its stability and reusability. Overall, the new NCs are therefore highly attractive for the remediation of TET pollution in water.

Electrochemical oxidation processes (eAOP) are a promising approach for the remediation of per- and polyfluoroalkyl substance (PFAS) due to its ease of operation, low energy needs and lack of auxiliary chemicals. In this study, we designed and utilized a boron-doped diamond anode in a two-electrode system to investigate the impact of the electrolyte composition and PFAS chain length on the eAOP performance. We varied the supporting anions (Na₂SO₄, NaCl, NaNO₃) and electrical conductivity (500–2000 μS cm⁻¹, constant current), and found no effect of supporting anions on PFAS removal. Varying the supporting anions, while maintaining constant electrical conductivity did not significantly vary the anodic voltage (p value = 0.99). We found a strong correlation between PFAS removal and their log n-octanol–water partitioning coefficient (r = 0.8), suggesting that PFAS sorption onto the electrode was a critical step in the degradation of PFASs. It was also demonstrated, for the first time for eAOPs, that gas bubbles generated in the system could capture and transport PFASs from the solution to the water surface, leading to loss of PFASs by electrochemical aerosolization (2–85%) after the bursting of bubbles. Fluorine mass balance for the treatment of PFOA and 6 : 2 FTS revealed ∼68% recovery post treatment, with the inorganic fluorine (48%) released during treatment being the primary component and ∼20% fluorine, unaccounted for. Results from this study highlight the impact of the supporting electrolyte and PFAS aerosolization on the treatment efficiency and provide insight into the mechanisms and system design to improve removal of PFASs utilizing an eAOP.