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Objective: This study examines the dynamic changes of stress hormones, including insulin (INS), fasting blood glucose (FBG), glucagon (Glu), and cortisol (Cort), in trauma patients. By monitoring these changes and observing acute pressure injury (API) occurrences on the skin, the research analyzes the influence of stress hormones on API development in trauma patients. Methods: A prospective analysis involved 218 trauma patients admitted to a grade III-A general hospital in Wenzhou from April 2021 to June 2023. Among them, 44 cases developed API (API group), and 174 cases did not (control group). Levels of INS, Cort, Glu, and FBG were measured in both groups. Additionally, Abbreviated Injury Scale-Injury Severity Score (AIS-ISS) surveys and API severity assessments were conducted. Correlations between stress hormone levels and AIS-ISS were discussed. The predictive effects of AIS-ISS and stress hormones on API occurrence in trauma patients were analyzed using receiver operating characteristic (ROC) curves. The relationship between stress hormone levels and API severity was also observed. Results: Study's outcomes indicated distinct relationships between stress hormone levels and API occurrence in trauma patients. Specifically, INS demonstrated a negative correlation with AIS-ISS, highlighting its potential as a significant factor. Glu, Cort, and FBG revealed positive associations, emphasizing their roles in influencing API development (P < .05). The diagnostic efficacy of stress hormones in predicting API occurrence, as represented by the Area Under Curve (AUC) = 0.8100. Notably, within the API group, INS levels demonstrated a decline with worsening API. Conversely, Glu, Cort, and FBG exhibited increases in tandem with the aggravation of API symptoms (P < .05). Conclusions: This research suggests that assessing stress hormone levels in clinical settings can effectively predict API occurrence. Early testing could aid in the development of preventive or intervention measures, reducing the incidence and harm of API in trauma patients.
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Antibacterial photodynamic therapy (aPDT) is regarded as one of the most promising antibacterial therapies due to its nonresistance, noninvasion, and rapid sterilization. However, the development of antibacterial materials with high aPDT efficacy is still a long-standing challenge. Herein, we develop an effective antibacterial photodynamic composite UiO-66-(SH)2@TCPP@AgNPs by Ag encapsulation and 4,4',4â³,4â´-(porphine-5,10,15,20-tetrayl)tetrakis(benzoic acid) (TCPP) dopant. Through a mix-and-match strategy in the self-assembly process, 2,5-dimercaptoterephthalic acid containing -SH groups and TCPP were uniformly decorated into the UiO-66-type framework to form UiO-66-(SH)2@TCPP. After Ag(I) impregnation and in situ UV light reduction, Ag NPs were formed and encapsulated into UiO-66-(SH)2@TCPP to get UiO-66-(SH)2@TCPP@AgNPs. In the resulting composite, both Ag NPs and TCPP can effectively enhance the visible light absorption, largely boosting the generation efficiency of reactive oxygen species. Notably, the nanoscale size enables it to effectively contact and be endocytosed into bacteria. Consequently, UiO-66-(SH)2@TCPP@AgNPs show a very high aPDT efficacy against Gram-negative and Gram-positive bacteria as well as drug-resistant bacteria (MRSA). Furthermore, the Ag NPs were firmly anchored at the framework by the high density of -SH moieties, avoiding the cytotoxicity caused by the leakage of Ag NPs. By in vitro experiments, UiO-66-(SH)2@TCPP@AgNPs show a very high antibacterial activity and good biocompatibility as well as the potentiality to promote cell proliferation.
Assuntos
Fotoquimioterapia , Porfirinas , Luz , Antibacterianos/farmacologia , Porfirinas/farmacologiaRESUMO
The aim of this experiment was to analyze the ameliorating effect of neural stem cells (NSCs) on focal cerebral ischemia (FCI) through GDNF/PI3K/AKT axis, so as to provide evidence for future clinical application of NSCs. In this study, the 15 Sprague-Dawley (SD) male rats were modeled for middle cerebral artery occlusion (MCAO)-induced FCI and then grouped: NSCs group was treated with NSC transplantation, GDNF/NSCs group was transplanted with recombinant adenovirus pAdEasy-1-pAdTrackCMV-GDNF-transfedcted NSCs, and the blank group was treated with normal saline transplantation. Rats were tested by rotarod and corner turn tests at 1 week and 4 weeks after NSC transplantation, and the levels of tumor necrosis factor-α (TNF-α), interleukin-6/8 (IL-6/8), superoxide dismutase (SOD) and malondialdehyde (MDA) were quantified. Then all rats were killed and their brain tissues were HE stained for the determination of and GDNF/PI3K/AKT axis-associated protein expression. The results of the experiment showed that: at the 1st and 4th week after transplantation, the time on the rod, number of turnings and SOD were the lowest in the blank group among the three groups, while IL-6, IL-8, TNF-α and MDA were the highest (P<0.05). Increased time on the rod, number of turnings and SOD, as well as decreased IL-6, IL-8, TNF-α and MDA were observed in NSCs and GDNF/NSCs groups after transplantation, with better performance in GDNF/NSCs group (P<0.05). Based on HE staining of brain tissue, GDNF/NSCs group had the most significant improvement in tissue injury and the highest GDNF, PI3K, AKT and p-AKT protein expression among the three groups (P<0.05). In conclusions, NSC transplantation can ameliorate neurological function in MCAO-induced FCI rats through the GDNF/PI3K/AKT axis.
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Isquemia Encefálica , Células-Tronco Neurais , Ratos , Masculino , Animais , Fator Neurotrófico Derivado de Linhagem de Célula Glial/metabolismo , Proteínas Proto-Oncogênicas c-akt/metabolismo , Interleucina-8/metabolismo , Fosfatidilinositol 3-Quinases/metabolismo , Ratos Sprague-Dawley , Interleucina-6/metabolismo , Fator de Necrose Tumoral alfa/metabolismo , Células-Tronco Neurais/metabolismo , Isquemia Encefálica/terapia , Isquemia Encefálica/metabolismo , Transplante de Células-Tronco/métodos , Infarto da Artéria Cerebral Média/terapia , Infarto da Artéria Cerebral Média/metabolismo , Superóxido Dismutase/metabolismoRESUMO
BACKGROUND: It is challenging to detect pressure injuries at an early stage of their development. OBJECTIVES: To assess the ability of an infrared thermography (IRT)-based model, constructed using a convolution neural network, to reliably detect pressure injuries. METHODS: A prospective cohort study compared validity in patients with pressure injury (n = 58) and without pressure injury (n = 205) using different methods. Each patient was followed up for 10 days. RESULTS: The optimal cut-off values of the IRT-based model were 0·53 for identifying tissue damage 1 day before visual detection of pressure injury and 0·88 for pressure injury detection on the day visual detection is possible. Kaplan-Meier curves and Cox proportional hazard regression model analysis showed that the risk of pressure injury increased 13-fold 1 day before visual detection with a cut-off value higher than 0·53 [hazard ratio (HR) 13·04, 95% confidence interval (CI) 6·32-26·91; P < 0·001]. The ability of the IRT-based model to detect pressure injuries [area under the receiver operating characteristic curve (AUC)lag 0 days , 0·98, 95% CI 0·95-1·00] was better than that of other methods. CONCLUSIONS: The IRT-based model is a useful and reliable method for clinical dermatologists and nurses to detect pressure injuries. It can objectively and accurately detect pressure injuries 1 day before visual detection and is therefore able to guide prevention earlier than would otherwise be possible. What is already known about this topic? Detection of pressure injuries at an early stage is challenging. Infrared thermography can be used for the physiological and anatomical evaluation of subcutaneous tissue abnormalities. A convolutional neural network is increasingly used in medical imaging analysis. What does this study add? The optimal cut-off values of the IRT-based model were 0·53 for identifying tissue damage 1 day before visual detection of pressure injury and 0·88 for pressure injury detection on the day visual detection is possible. Infrared thermography-based models can be used by clinical dermatologists and nurses to detect pressure injuries at an early stage objectively and accurately.
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Raios Infravermelhos , Úlcera por Pressão , Termografia , Humanos , Estudos Prospectivos , Curva ROC , Termografia/métodosRESUMO
This study aimed to investigate the relationship between the severity of albuminuria and wound healing in type 2 diabetic foot ulcers. A total of 121 patients with diabetic foot ulcers were recruited from January 2015 to June 2017 and divided into nonproliferation and proliferation groups according to their healing status. Univariate and multivariate logistic regression were performed to assess the risk factors of wound proliferation. Skin biopsies were also taken from normal tissue near the wound in 54 participants. The microvessel density as well as the relationships among the microvessel density, albuminuria and wound proliferation were evaluated. Results showed that in a multiple linear regression model, factors including body-mass index, microalbuminuria, and macroalbuminuria showed independently significant association with wound healing in patients. The receiver operating characteristic curve analysis indicated albuminuria as a predicator for wound healing with a cutoff value of 32 mg/g. Meanwhile, normoalbuminuric patients showed significantly higher level of skin microvessels density than microalbuminuria and macroalbuminuria patients, while microalbuminuria patients also had statistically more microvessels that macroalbuminuria patients. The microvessel density were statistically significantly higher in the proliferation group than that in the nonproliferation group. In summary, this study suggested that albuminuria can be used as an independent indicator for the healing of type 2 diabetic foot ulcers.
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Albuminúria/diagnóstico , Diabetes Mellitus Tipo 2/complicações , Pé Diabético/complicações , Cicatrização , Idoso , Albuminúria/etiologia , Índice de Massa Corporal , Pé Diabético/diagnóstico , Pé Diabético/metabolismo , Feminino , Seguimentos , Humanos , Masculino , Densidade Microvascular , Microvasos/patologia , Estudos Retrospectivos , Índice de Gravidade de DoençaRESUMO
AIMS AND OBJECTIVES: To verify the ability of infrared thermography in objectively identifying pressure injury and its application value in the early warning of pressure injury. BACKGROUND: There is subjectivity in assessing the risk of pressure injury as well as diagnosis in clinical settings, which makes early detection and prevention difficult. DESIGN: Prospective, cohort study. METHOD: Four hundred and fifteen patients admitted to the adult intensive care units were enrolled by a convenience sampling method, and they received a follow-up monitoring for 10 days. The risk of pressure injury was assessed via Braden scale, and thermal images of sacral area were obtained by infrared thermal imager once a day. The predictive effects of infrared thermography and Braden scale on pressure injury were compared by the receiver operating characteristic curve from which the optimal cut-off value of skin temperature for predicting pressure injury was determined. The effect of skin temperature on pressure injury was described and compared, using Kaplan-Meier curve and Cox proportional hazard regression model, respectively. We followed STROBE checklist for reporting the study. RESULTS: The relative temperature of sacral area was negatively correlated with the risk of pressure injury. The efficiency of infrared thermography for diagnosing pressure injury was better than that of Braden scale. Based on the relative temperature optimal cut-off value (-0.1°C), Kaplan-Meier curve and Cox proportional hazard regression model analysis showed the incidence of pressure injury with relative temperature below -0.1°C was higher than the group with relative temperature above -0.1°C. CONCLUSIONS: Infrared thermography can objectively and accurately identify local hypothermia warnings of pressure injury before visual recognition. The application of infrared thermography into routine pressure injury risk assessment provides a timely and reliable method for nursing practitioners. RELEVANCE TO CLINICAL PRACTICE: Infrared thermography has great value of clinical application in daily pressure injury assessment. It is of great significance to make a faster and more objective clinical judgement for patients at risk of pressure injury.
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Úlcera por Pressão/diagnóstico , Termografia , Adulto , Estudos de Coortes , Humanos , Incidência , Úlcera por Pressão/enfermagem , Estudos Prospectivos , Temperatura CutâneaRESUMO
Ginkgo biloba extract (GBE) had several effects on the human body as one of the widely used phytopharmaceuticals, but it had no application in microbial enhancement in the environmental field. The study focused on the impact of GBE on denitrification specifically under neutral conditions. At the identified optimal addition ratio of 2% (v/v), the system exhibited a noteworthy increase in nitrate reduction rate (NRR) by 56.34%, elevating from 0.71 to 1.11 mg-N/(L·h). Moreover, the extraction of microbial extracellular polymeric substance (EPS) at this ratio revealed changes in the composition of EPS, the electron exchange capacity (EEC) was enhanced from 87.16 to 140.4 µmol/(g C), and the transfer impedance was reduced within the EPS. The flavin, fulvic acid (FA), and humic acid (HA) provided a π-electron conjugated structure for the denitrification system, enhancing extracellular electron transfer (EET) by stimulating carbon source metabolism. GBE also improved electron transfer system activity (ETSA) from 0.025 to 0.071 µL O2/(g·min·prot) and the content of NADH enhanced by 22.90% while significantly reducing the activation energy (Ea) by 85.6% in the denitrification process. The synergy of improving both intracellular and extracellular electron transfer, along with the reduction of Ea, notably amplified the initiation and reduction rates of the denitrification process. Additionally, GBE demonstrated suitability for denitrification across various pH levels, enhancing microbial resilience in alkaline conditions and promoting survival and proliferation. Overall, these findings open the door to potential applications of GBE as a natural additive in the environmental field to improve the efficiency of denitrification processes, which are essential for nitrogen removal in various environmental contexts.
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Desnitrificação , Matriz Extracelular de Substâncias Poliméricas , Extrato de Ginkgo , Humanos , Elétrons , Extratos Vegetais , Nitrogênio , Reatores BiológicosRESUMO
Copper pollution of the world's water resources is becoming increasingly serious and poses a serious threat to human health and aquatic ecosystems. With reported copper concentrations in wastewater ranging from approximately 2.5 mg/L to 10,000 mg/L, a summary of remediation techniques for different contamination scenarios is essential. Therefore, it is important to develop low-cost, feasible, and sustainable wastewater removal technologies. Various methods for the removal of heavy metals from wastewater have been extensively studied in recent years. This paper reviews the current methods used to treat Cu(II)-containing wastewater and evaluates these technologies and their health effects. These technologies include membrane separation, ion exchange, chemical precipitation, electrochemistry, adsorption, and biotechnology. Thus, in this paper, we review the efforts and technological advances made so far in the pursuit of more efficient removal and recovery of Cu(II) from industrial wastewater and compare the advantages and disadvantages of each technology in terms of research prospects, technical bottlenecks, and application scenarios. Meanwhile, this study points out that achieving low health risk effluent through technology coupling is the focus of future research.
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Metais Pesados , Poluentes Químicos da Água , Humanos , Cobre/análise , Águas Residuárias , Ecossistema , Íons , Poluentes Químicos da Água/análise , Adsorção , Concentração de Íons de HidrogênioRESUMO
Sodium humate (SH) is one of the derivatives humic substances, which can be utilized for heavy metal removal from water due to its containing plenty of functional groups. In this study, a double network hydrogel SH/polyacrylamide (SH/PAM) was synthesized by a simple free-radical polymerization and used for Cu2+ and Pb2+ removal from water. The adsorption process can be well described by Langmuir-Freundlich model, indicating that both physical and chemical adsorption were involved. X-ray photoelectron spectroscopy (XPS) characterization demonstrated that complexation was the main mechanism for the adsorption. Two-dimensional correlation analysis of FTIR (2D-FTIR-COS) results showed that the variation order of functional groups during Cu2+ and Pb2+ adsorption in the following order: COOH ≈ -CO > -OH > C-O and -COOH ≈ C-O > -CO > -OH, respectively. According to the density functional theory (DFT) calculation results, the O atom of SH in the COO- was the main adsorption site. Meanwhile, the adsorption energy of Pb2+ was more negative than that of Cu2+ and the orbital hybridization between O atom of SH and Pb2+ was denser than that of Cu2+, which suggested that SH/PAM had a stronger combining capacity for Pb2+ than Cu2+. Therefore, the adsorption capacity for Pb2+ was larger than Cu2+. Moreover, the removal efficiencies are 30.2% for Al, 98.79% for Cu, 99.0% for Fe, 17.2% for Mn, 93.4% for Pb, and 62.4% for Zn in actual acid mine drainage using 6 g L-1 adsorbent. Collectively, this study not only provided a new adsorbent for heavy metal removal but also explicated the mechanism of heavy metal removal by SH from molecule and electron perspective, which is helpful for the application of SH in the environmental field.
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Metais Pesados , Poluentes Químicos da Água , Chumbo , Hidrogéis/química , Poluentes Químicos da Água/análise , Metais Pesados/análise , Água , AdsorçãoRESUMO
Sulfur-based autotrophic bioremediation is recognized as an environmentally-friendly and effective method for the treatment of Cr(VI) in groundwater. However, inorganic carbon (IC), especially IC-rich solid kitchen waste, has rarely been reported as an important factor in the autotrophic process. In China, kitchen waste containing IC is generated in large quantities, and in combination with Cr(VI) autotrophic treatment technology in groundwater can achieve a win-win situation. Herein, the efficiency of Cr(VI)-bioreduction coupling solid inorganic carbon (SIC) (e.g. marble, egg shell, oyster shell, and NSAD synthetic material) and liquid inorganic carbon (LIC) was compared for the first time. After 18 d incubation, there were significant differences in Cr(VI) reduction efficiency and microbial community between SIC-bioreactors and LIC-bioreactors. Higher electron transfer activity, greater bioavailability of organics, and multiple Cr(VI) reductases were detected in SIC-biosystems, which effectively promoted Cr(VI) energy metabolism and enzyme-mediated biological reduction. High-throughput 16S rRNA gene sequencing reveled multiple cooperative mechanism in different substrate biosystems. This study not only advances the understanding of SIC coupled with Cr(VI) autotrophic bioreduction, but also provides new insights for the treatment of solid kitchen waste and groundwater bioremediation.
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Carbono , Cromo , Animais , RNA Ribossômico 16S , Oxirredução , Cromo/metabolismo , Enxofre , Carbonato de CálcioRESUMO
Microbial techniques have been extensively used for the remediation of nitrate and V(V) co-contaminations, but the mechanisms of electron and substances transport and metabolism of co-contaminations under oligotrophic niche have been largely overlooked. This study quantified the electron transfer and consumption, substance transfer, and metabolic pathways in the nitrate and V(V) co-contamination system under oligotrophic condition to explore the underlying mechanisms by characterizing the products and elucidating conventional cognitive pathways. This study compared the composition of the precipitates under the conditions of sufficient and insufficient carbon sources using energy-dispersive X-ray spectroscopy, X-ray diffraction and X-ray photoelectron spectroscopy, and discovered the re-oxidation process of the already reduced V(IV). Electronic evidence for the re-oxidation process of V(IV) was also provided by electron transfer and quantitative analysis. Besides, this study found that the electron contribution ratio of NO3--N â NO2--N and V(V) â V(IV) reduction was 40.2:1. In addition, based on the functional prediction of PICRUSt 2, it was found that the utilization of intracellular reserve carbon source and enzymes in the transport chain were enhanced in oligotrophic microbiology niche. These results provide new insights into the stability of co-contamination reduction in oligotrophic microbiology niche and demonstrate a new mobilization pathway for V(V) in oligotrophic systems.
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Nitratos , Vanádio , Vanádio/metabolismo , Elétrons , Transporte de Elétrons , OxirreduçãoRESUMO
The coexistence of nitrate and V(V) in groundwater aquifers poses potential threats to ecological environment and public health. However, much remains to be elucidated about how the complex microbial community coupled nitrate and V(V) simultaneous bio-reduction with carbon source oxidation. For the first time, it was demonstrated that denitrification and V(V) bio-reduction occur by using corn straw as the sole carbon and energy source. Corn straw was proved to have efficient denitrification and V(V) bio-reduction performance in various environments, especially at V(V) concentrations of 100 mg/L for optimal V(V) reduction rate (19.25 mg/L·d) and at pH of 11 with the best nitrate reduction rate (3.12 d-1). In addition, an interesting phenomenon was found that the release of V(V) occurred when the carbon source was insufficient and the competitive electron acceptor (NO3--N) existed. Metagenomic analysis showed that the addition of corn straw increased the abundance of genes related to metal resistance, cytochrome and dimethyl sulfoxide, and increased the abundance of glycolytic process, which may play a vital role in facilitating the reduction of V(V). These findings can provide basic suggestions for improving the mechanism of V(V) reduction pathway and provide guidance for the remediation of groundwater polluted by nitrate and V(V).
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Água Subterrânea , Nitratos , Carbono/metabolismo , Desnitrificação , Nitratos/metabolismo , Óxidos de Nitrogênio , Zea mays/metabolismoRESUMO
Nitrate, as the most stable form of nitrogen pollution, widely exists in aquatic environment, which has great potential threat to ecological environment and human health. Heterotrophic denitrification, as the most economical and effective method to treat nitrate wastewater, has been widely and deeply studied. From the perspective of heterotrophic denitrification, this review discusses nitrate removal in the aquatic environment, and the behaviors of different carbon source types were classified and summarized to explain the cyclical evolution of carbon and nitrogen in global biochemical processes. In addition, the denitrification process, electron transfer as well as denitrifying and hydrolyzing microorganisms among different carbon sources were analyzed and compared, and the commonness and characteristics of the denitrification process with various carbon sources were revealed. This study provides theoretical support and technical guidance for further improvement of denitrification technologies.
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Desnitrificação , Purificação da Água , Carbono , Processos Heterotróficos , Humanos , Nitratos , Nitrificação , Nitrogênio , Águas ResiduáriasRESUMO
Heterotrophic denitrification based on solid carbon sources has been widely investigated for nitrogen removal in recent years. In this study, the response of the heterotrophic denitrification process under different K+ concentrations was clarified. Additionally, the denitrification enhancement mechanism was revealed and resource utilization of agricultural waste was achieved. A series of batch tests were conducted to study the effect of different K+ concentrations on the denitrification performance, dissolved organic matter (DOM) dissolution and microbial community structure. Results demonstrate that the threshold of K+ concentration for the NO3--N and NO2--N reduction rates were 229.78⯱â¯25.80 and 159.10⯱â¯24.60â¯mg-K/L, respectively. Excitation-emission matrix (EEM) analysis identified the main DOM components associated with tyrosine-like, tryptophan-like and humic-like substances, as well as illustrated the evolutionary behavior and utilization of DOM. High throughput 16S rRNA gene sequencing indicates that a K+ concentration of 229.78⯱â¯25.80â¯mg-K/L exhibited the highest diversity of functional species associated with fermentation and denitrification. The genera Pseudomonas and Thiobacillus were the unique denitrifiers at this K+ concentration. The correlation of K+ concentration, DOM dissolution of different regions and microorganism structure were analyzed using correlation matrix and PCA, and the appropriate K+ concentration of different functional microorganisms survival was optimized by this analysis method.
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Desnitrificação , Água Subterrânea , Reatores Biológicos , Nitratos , Nitrogênio , Potássio , RNA Ribossômico 16S , Águas ResiduáriasRESUMO
Nitrate pollution presents a serious threat to the environment and public health. As an excellent heterotrophic denitrification carbon source, banana peel (a kind of agricultural waste) provides a feasible alternative to deal with the persistent high concentrations of nitrate pollution. Although the feasibility and economy of banana peel for denitrification have already been reported, the long-term stability and mechanism were still unclear. The coupling mechanism of organic matters and microorganism in the denitrification process was systematically investigated through a 17-cycle experiment. The results showed that significant NO3--N removal load and rate of 164.42 mg/g and 4.69 mg/(L·h) after long-term tests could be obtained. Organic matter analysis and 16S rRNA sequencing showed that the evolution of organic matter was dominated by Anaerolineaceae (fermenting bacteria), and, in the final step, the humification of organic matter was realized. Moreover, the presence of Lentimicrobium (denitrifying bacteria) was indispensable for the continuous removal of high concentrations of nitrate. The main functional gene of nitrogen transformation in this reaction system was NirS (haem-containing). This lab-scale heterotrophic denitrification process could contribute to a better understanding of the carbon and nitrogen cycles in the biogeochemical cycles to some extent, and it also provides a reference for the construction of highly efficient nitrate degradation reactors, based on agricultural wastes.
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Reatores Biológicos/microbiologia , Desnitrificação , Musa , Bactérias/metabolismo , Carbono/metabolismo , Desnitrificação/genética , Processos Heterotróficos , Nitratos/metabolismo , Nitrogênio/metabolismo , Ciclo do Nitrogênio , RNA Ribossômico 16S/genética , Águas Residuárias/químicaRESUMO
Landfill leachate is a type of complex organic wastewater, which can easily cause serious negative impacts on the human health and ecological environment if disposed improperly. Electrochemical technology provides an efficient approach to effectively reduce the pollutants in landfill leachate. In this review, the electrochemical standalone processes (electrochemical oxidation, electrochemical reduction, electro-coagulation, electro-Fenton process, three-dimensional electrode process, and ion exchange membrane electrochemical process) and the electrochemical integrated processes (electrochemical-advanced oxidation process (AOP) and biological electrochemical process) for landfill leachate treatment are summarized, which include the performance, mechanism, application, existing problems, and improvement schemes such as cost-effectiveness. The main objective of this review is to help researchers understand the characteristics of electrochemical treatment of landfill leachate and to provide a useful reference for the design of the process and reactor for the harmless treatment of landfill leachate.
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The humic-like substances were the main organic components in most wastewater (e.g. domestic sewage, toilet wastewater and landfill leachate). Two types of actual humic-like substances (fulvic acid (FA) and biologically treated landfill leachate (BTLL)) were selected to describe the changes in the properties of humic-like substances (complexation ability, aromaticity and mobility) during electrochemical oxidation. Meanwhile, the acute cytotoxicity of FA and BTLL was also tested by acute toxicological test of luminescent bacteria. The results showed that the consumption of coordinating groups such as phenolic groups and hydrogen bonds reduced the complexation ability of FA and BTLL. The functional groups were degraded with the removal order of quinone group, phenolic group and aromatic group, and finally realized the molecular saturation and aromaticity decrease for humic-like substances. The mobility of FA and BTLL was decreased because of the enhancement of hydrophobicity during electrolysis process. Furthermore, the available chlorine produced during electrochemical oxidation was the main acute cytotoxicity substance, therefore, it is necessary to remove it before discharge in order to reduce ecological risks. This study provides a basis for understanding and evaluating the electrochemical degradation process of humic-like substances in detail.
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Benzopiranos/análise , Recuperação e Remediação Ambiental/métodos , Substâncias Húmicas/análise , Águas Residuárias/química , Poluentes Químicos da Água/análise , Aliivibrio fischeri/efeitos dos fármacos , Técnicas Eletroquímicas , Substâncias Húmicas/toxicidade , Oxirredução , Poluentes Químicos da Água/toxicidadeRESUMO
This study presented a novel alternating-anode electrochemical system (AAES) based on single electrolytic cell for the treatment of nitrogen-containing refractory organic wastewater (NOW). The core of AAES lies in the alternating working of iron anode and DSA anode to integrate different electrochemical processes. The biologically treated landfill leachate (BTLL) was selected as a practical NOW for assessing the performance of AAES. The results indicated that after 140â¯min of electrolytic reaction, the removal efficiency of chemical oxygen demand and total nitrogen (TN) using AAES was found to be 76.9 and 98.9%, respectively. The main component of dissolved organic matter (DOM) in BTLL included humic-like substances, which could be degraded into small-molecule DOM, such as fulvic-like substances and protein-like substances, by available chlorine and hydroxyl radicals present in AAES. Cathode reduction (NOx--Nâ¯ââ¯NH4+-N and N2) under iron anode and indirect oxidation (NH4+-Nâ¯ââ¯N2) under DSA anode were the main pathways to remove TN from NOW. Owing to the redox conditions created by the alternating anodes, the main stable crystalline forms of precipitates obtained from AAES were Fe3O4 and γ-Fe2O3, which could be separated by using the external magnetic field. The findings of this study may provide a feasible solution for the advanced electrochemical treatment of NOW in a single electrolytic cell as well as rapid separation of precipitates.