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•BDD electro-oxidation coupled with NF filtration have been applied for secondary wastewater treatment.•The BDD electrode could produces •OH so that it can effectively degrade SMZ and ...organic compounds.•BDD electro-oxidation could mitigate NF membrane biofouling.•BDD electro-oxidation combined with NF filtration could achieve high quality of permeate.
In this study, a boron-doped diamond (BDD) electro-oxidation technology coupled with nanofiltration membrane (EO-NF) technology was investigated for its effectiveness in removing antibiotics (i.e., sulfamethazine:SMZ) and mitigating biofouling during secondary wastewater treatment. The result showed that EO obtained an effective SMZ removal, owing to the ·OH generation observed by Electron paramagnetic resonance (EPR) analysis; complete elimination of SMZ was found under the high current density (30 mA/cm2) and long Electrolysis Time (ET = 60 min). Meanwhile, EO-NF process enabled to reduce COD content from 60 mg/L to nearly 5 mg/L. Furthermore, regardless of the effect of EO process, NF could retain most NH3-N because of the excellent performance of NF for ions rejection, and its permeate concentration was below 0.5 mg/L. EO was able to reduce membrane fouling notably, increasing the final flux (15 L/(m2·h)) of NF by 25.1% during long-term operation (240 h). Scanning electron microscopy-Energy dispersive spectrometry (SEM-EDS) showed that a porous layer formed on the vicinity of NF membrane in the case of filtrating EO effluent, in contrast to a uniform and dense biofouling layer generated during the direct NF. Besides, the content of adenosine triphosphate (ATP) and the number of bacterial colonies in the retentate of the EO-NF process were greater than those of the direct NF process. This resulted in a smaller amount of extracellular polymeric substances (EPS) attaching to the membrane surface, decreasing the tightness and hardness of the fouling layer in the case of EO, as indicated by CLSM analysis. Overall, considering its ability to effectively eliminate persistent contaminants and reduce membrane fouling, BDD-based EO is considered a promising pre-treatment option for future NF applications.
Background
COVID-19 pandemic is not yet over, and it has been generating lots of plastic wastes that become a big concern. To catch the virus, for example, no matter via antigen or PCR test, swab is ...generally used for sampling. Unfortunately, the swab tip is commonly made of plastics, and thus it can be a potential source of microplastics. This study aims to propose and optimise several Raman imaging to identify the microplastic fibres released from different COVID-19 test swabs.
Results
The results show that Raman imaging can effectively identify and visualise the microplastic fibres released from the swabs. In the meantime, on the surface of the fibres, additives such as titanium oxide particles are also captured for some brands of swabs. To increase the result certainty, scanning electron microscope (SEM) is first employed to get the morphology of the released microplastic fibres, along with Energy-dispersive X-ray spectroscopy (EDS) to confirm the presence of titanium element. Then, Raman imaging is advanced to identify and visualise the microplastics and titanium oxide particles, from different characteristic peaks in the scanning spectrum matrix. To further increase the imaging certainty, these images can be merged and cross-checked using algorithms, or the raw data from the scanning spectrum matrix can be analysed and decoded via chemometrics, such as principal component analysis (PCA). Beyond the advantages, the disadvantages of the confocal Raman imaging (affected by focal height) and algorithms (non-supervised calculation) are also discussed and intentionally corrected. In brief, the imaging analysis (particularly the combined SEM with Raman) is recommended to avoid the possible result bias that might be generated from the single spectrum analysis at a selective but random position.
Conclusions
Overall, the results indicate that Raman imaging can be a useful tool to detect microplastics. The results also send us a strong warning that, if we worry about the potential microplastics contamination, we should be cautious to select the suitable COVID-19 testing kits.
Radio sensitivity serves as a commonly used parameter in wireless receiver systems. When excess antenna noise is introduced into the system, it results in a reduction of radiated sensitivity. This ...phenomenon, referred to as radiated sensitivity desensitization, occurs upon connecting antennas. This paper elucidates a shared impedance noise coupling mechanism, which sheds light on how passive antennas can introduce excess noise into the wireless system. To address this apparent contradiction, the paper introduces the general theory of antenna noise temperature, providing an explanation for the mechanism of noise coupling through a shared impedance path. Additionally, a mathematical expression for radiated sensitivity is presented in this paper. An understanding of this noise coupling mechanism holds significant implications for various fields, including antenna technology, electromagnetic compatibility, radio science, remote sensing, and wireless communication systems.
•Polyurethane sponge showed varying sorption capacities for micropollutants.•Compound-specific variation in removal (25.9–96.8%) was observed in the MBBR.•Biodegradation was the major removal ...mechanism during the MBBR treatment.•Sorption was important for the removal of persistent compounds.
This study investigated the removal of micropollutants using polyurethane sponge as attached-growth carrier. Batch experiments demonstrated that micropollutants could adsorb to non-acclimatized sponge cubes to varying extents. Acclimatized sponge showed significantly enhanced removal of some less hydrophobic compounds (logD<2.5), such as ibuprofen, acetaminophen, naproxen, and estriol, as compared with non-acclimatized sponge. The results for bench-scale sponge-based moving bed bioreactor (MBBR) system elucidated compound-specific variation in removal, ranging from 25.9% (carbamazepine) to 96.8% (β-Estradiol 17-acetate) on average. In the MBBR system, biodegradation served as a major removal pathway for most compounds. However, sorption to sludge phase was also a notable removal mechanism of some persistent micropollutants. Particularly, carbamazepine, ketoprofen and pentachlorophenol were found at high concentrations (7.87, 6.05 and 5.55μg/g, respectively) on suspended biosolids. As a whole, the effectiveness of MBBR for micropollutant removal was comparable with those of activated sludge processes and MBRs.
Plastic products are used ubiquitously and can potentially release microplastics and nanoplastics into the environment, for example, products such as the silicone sealant used in kitchens. It is ...important to develop an effective method to monitor these emerging contaminants, as reported herein. By using advanced Raman imaging to characterize microplastics and nanoplastics from hundreds of spectra in a scanning spectrum matrix and not from a single spectrum or peak, the signal-to-noise ratio can be significantly increased, from a statistical point of view. The diffraction of the laser spot usually constrains the imaging resolution (such as at ∼300 nm), which is also pushed to the limit in this report by shrinking the scanning pixel size down to ∼50 nm to capture and image small nanoplastics effectively. To this end, image reconstruction is developed to successfully pick up the meaningful Raman signal and intentionally avoid the noise. The results indicate that the silicone sealant in a kitchen can release a significant amount of microplastics and nanoplastics. Overall, advanced Raman imaging can be employed to characterize the microplastics and even nanoplastics that are smaller than the diffraction limit of the laser via Raman imaging and image reconstruction toward deconvolution.
Industrial dyeing produces highly polluting wastewater and threatens the environment. Effective treatment of dyeing wastewater is a crucial step to prevent toxic chemicals from entering receiving ...waters. This study aimed to assess a modified attapulgite (ATP)-based adsorbent for dyeing wastewater purification by introducing chitosan (CTS) and titanium dioxide (TiO
2
) into the adsorbent material named TiO
2
/CTS/ATP. It was found that after modification, the adsorbent showed a lower hydrophilicity, as demonstrated by an increase in the water contact angle from 9.1° to 42°, which could reduce the water adsorption tendency and potentially facilitate contaminants adherence. The modification also led to a significantly increased specific surface area of 79.111 m
2
/g from 3.791 m
2
/g and exhibited more uniform and smaller particle size (reduced from 3.99 to 2.52 μm). When the TiO
2
/CTS/ATP adsorbent was applied to the adsorption of Congo red solution, the adsorption efficiency was observed to reach to 97.6% at the dosage of 0.5 g/L. Furthermore, the combination of adsorption and ultrafiltration was able to achieve 99% Congo red removal. Adsorption pretreatment prior to the ultrafiltration also enabled to reduce membrane fouling, increased the reversible membrane fouling, and resulted in a considerably lower transmembrane pressure as compared with the direct ultrafiltration filtration system.
Surgery remains the primary form of treatment for infective endocarditis (IE). However, it is not clear what type of prosthetic valve provides a better prognosis. We conducted a meta-analysis to ...compare the prognosis of infective endocarditis treated with biological valves to cases treated with mechanical valves.
Pubmed, Embase and Cochrane databases were searched from January 1960 to November 2016.Randomized controlled trials, retrospective cohorts and prospective studies comparing outcomes between biological valve and mechanical valve management for infective endocarditis were analyzed. The Newcastle-Ottawa Scale(NOS) was used to evaluate the quality of the literature and extracted data, and Stata 12.0 software was used for the meta-analysis.
A total of 11 publications were included; 10,754 cases were selected, involving 6776 cases of biological valves and 3,978 cases of mechanical valves. The all-cause mortality risk of the biological valve group was higher than that of the mechanical valve group (HR = 1.22, 95% CI 1.03 to 1.44, P = 0.023), as was early mortality (RR = 1.21, 95% CI 1.02 to 1.43, P = 0.033). The recurrence of endocarditis (HR = 1.75, 95% CI 1.26 to 2.42, P = 0.001), as well as the risk of reoperation (HR = 1.79, 95% CI 1.15 to 2.80, P = 0.010) were more likely to occur in the biological valve group. The incidence of postoperative embolism was less in the biological valve group than in the mechanical valve group, but this difference was not statistically significant (RR = 0.90, 95% CI 0.76 to 1.07, P = 0.245). For patients with prosthetic valve endocarditis (PVE), there was no significant difference in survival rates between the biological valve group and the mechanical valve group (HR = 0.91, 95% CI 0.68 to 1.21, P = 0.520).
The results of our meta-analysis suggest that mechanical valves can provide a significantly better prognosis in patients with infective endocarditis. There were significant differences in the clinical features of patients receiving a biological valve compared to patients receiving a mechanical valve. A large, multicenter retrospective study included in our meta-analysis suggested that any mortality risk of the biological valve group was significant higher than that of the mechanical valve group. However, the risk was no different after risk was adjusted. So, we thought the reason for this result may be related to the characteristics of the patient rather than valve dysfunction. It is still necessary to future randomized studies to verify this conclusion.
Borosilicate glasses are the most potential matrices to vitrify high-level nuclear wastes. However, the low solubility of Mo, which is usually one of the main elements in HLWs coming from the nuclear ...power stations, is a main limitation for their application in vitrification. In this paper, the effect of the substitution of Al
2
O
3
for CaO on Mo solubility in a modified SiO
2
–B
2
O
3
–Na
2
O–CaO borosilicate glass is investigated in detail. The results show that the solubility of Mo can be increased up to 4 mol % at least in the borosilicate glasses. The mechanism of Al
2
O
3
substitution for CaO to improve the solubility of Mo has been explained in detail by analyzing the changes of the cations for compensating
units and the depolymerized regions. It can be concluded that the borosilicate glasses with high substitution of Al
2
O
3
(15 or 20 mol %) are potential matrices to immobilize molybdenum-rich high-level nuclear wastes.
In order to reduce the probability of automobile safety incidents, the in-vehicle occupant monitoring is indispensable. However, occupant monitoring using frequency-modulated continuous wave (FMCW) ...radar can be challenging due to the interference from passengers’ posture, movement, and the presence of multiple people. This paper proposes an improved method for generating point clouds using FMCW radar. The approach involves point cloud clustering, post-processing operations such as segmentation, merging, and filtering of the clustered point cloud to match the actual in-vehicle environment, and a state machine combination step. Experimental results show that the proposed method can achieve high recognition accuracy in scenarios with multiple passengers who are moving and sitting in a relaxed manner.
Total oxidisable precursor (TOP) assay can oxidise some per- and polyfluoroalkyl substances (PFASs) and their precursors, most of which cannot be quantitatively detected so far, and convert them to ...detectable PFASs, such as perfluoroalkyl acids (PFAAs). However, the conversion is constrained by the complexity of the target samples, including co-existent organics, unknown PFAS precursors, and background. In this study, the TOP assay is modified to increase the oxidation and conversion efficiency by changing the initial concentration of target sample, increasing oxidising doses, time, temperature, etc. The modified TOP assay is applied to test several aqueous film-forming foams (AFFF) and a PFAS-contaminated soil extract. The sum concentrations of the detectable PFASs are increased by up to ∼534× in the AFFF samples and ∼7× in the PFAS-contaminated soil extract. The detectable fluorotelomer sulfonate (FTS, such as 6:2/8:2 FTS) is accounted as an oxidation indicator to monitor the oxidation and conversion progress of the oxidisable PFASs precursors to the detectable PFASs. Overall, the modified TOP assay could be an appropriate method for identifying missing PFASs mass in complex matrices by detecting the PFASs precursors effectively.
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