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AIM: To investigate the types of bacteria in patients with eye infections in Suzhou and their drug resistance to commonly used antibacterial drugs. METHODS: The clinical data of 155 patients were retrospectively collected in this study, and the pathogenic bacteria species and drug resistance of each pathogenic bacteria were analyzed. RESULTS: Among the 155 patients (age from 12 to 87 years old, with an average age of 57, 99 males and 56 females) with eye infections (160 eyes: 74 in the left eye, 76 in the right eye and 5 in both eyes, all of which were exogenous), 71 (45.81%) strains were gram-positive bacteria, 23 (14.84%) strains were gram-negative bacteria and 61 (39.35%) strains were fungi. Gram-positive bacteria were highly resistant to penicillin and erythromycin (78.87% and 46.48% respectively), but least resistant to vancomycin at 0. Gram-negative bacteria were highly resistant to cefoxitin and compound sulfamethoxazole (100% and 95.65% respectively), but least resistant to meropenem at 0. Comparison of the resistance of gram-positive and gram-negative bacteria to some drugs revealed statistically significant differences (P<0.05) in the resistance of both to cefoxitin, cotrimoxazole, levofloxacin, cefuroxime, ceftriaxone and ceftazidime, and both had higher rates of resistance to gram-negative bacteria than to gram-positive bacteria. The distribution of bacterial infection strains showed that Staphylococcus epidermidis was the most common strain in the conjunctiva, cornea, aqueous humor or vitreous body and other eye parts. Besides, Fusarium and Pseudomonas aeruginosa were also among the most common strains of conjunctival and corneal infections. CONCLUSION: Gram-positive bacteria are the dominant bacteria in eye infections, followed by gram-negative bacteria and fungi. Considering the resistance of gram-negative bacteria to multiple drugs, monitoring of bacteria should be strengthened in eye bacterial infections for effective prevention and control to reduce complications caused by eye infections.
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Ammonium-containing wastewater could cause the promotion of eutrophication and a hindrance to the disinfection of water supplies. In this study, the feasibility of removing low-concentration ammonium nitrogen from synthetic and real wastewater by electrochemical oxidation was investigated. Using laboratory-scale electrochemical systems, the effects of chloride concentration, current density, anode materials, cathode materials, electrode gap, initial ammonium concentration and three-dimensional particles on the removal of ammonium nitrogen and current efficiency (CE) were evaluated. Ammonium nitrogen removal was mainly dependent upon anode materials and current density. The performance of two- and three-dimensional electrochemical oxidation systems was comparatively discussed. Both particle electrodes could enhance ammonium nitrogen removal and increase CE. However, the mechanism of the process seemed to be different. Moreover, the interaction of zeolites adsorption and electrochemical oxidation on the anode in a three-dimensional system could favor the regeneration of zeolites. Surface morphology of the used Ru-Ir-Sn/Ti anode revealed its longer working life of electrocatalysis. The result of ammonium degradation for a real wastewater treatment plant effluent showed the degradation rates in a three-dimensional system increased by 1.4 times those in a two-dimensional system.
Assuntos
Técnicas Eletroquímicas/métodos , Compostos de Amônio Quaternário/isolamento & purificação , Eliminação de Resíduos Líquidos/métodos , Águas Residuárias/química , Purificação da Água/métodos , Técnicas Eletroquímicas/instrumentação , Eletrodos , Metais/química , Oxirredução , Óxidos/química , Compostos de Amônio Quaternário/químicaRESUMO
With the growing concern regarding emission of volatile organic compounds (VOCs) from wastewater treatment plants (WWTPs), the relationship between the VOC emission rates and the associated public health risks has been rarely discussed. The objective of this study was to examine and compare the VOC emission rates and cancer and non-cancer risks by inhalation intake, using a municipal WWTP in China as an example, with respect to the effects of treatment technologies, VOC species, and seasonal variation. Given the treatment technology considered, the emission rates of VOCs in this study were estimated by means of mass balance or calculated on the molecular level. From the viewpoints of both emission rates and cancer and non-cancer risks, sedimentation was the treatment technology with the highest health risks to the workers. Slightly lower VOC emission rates and health risks than those for sedimentation were observed in anaerobic treatment. Although the aeration significantly enhanced the VOC emission rates in the aerobic treatment process, the associated health risks were limited due to the low VOC concentrations in the gas phase, which were likely attributed to the strong mixing and dilution with fresh air by aeration. Amongst the VOCs investigated, benzene was the VOC with both a relatively high emission rate and health risk, while trichloroethylene possessed a high emission rate but the lowest health risk. Without strong interfacial aeration and turbulence between the water and atmosphere, the effects of treatment technology and seasonal variation on the health risks might be connected to the VOC emission rates, while the effect of VOC species depended considerably on the respective cancer slope factors and reference concentrations; the employment of aeration provided a different conclusion in which the emission rates were enhanced without a significant increase in the related cancer risks. These findings can provide insight into future health risk management and reduction strategies for workers in WWTPs.
Assuntos
Poluentes Atmosféricos/análise , Compostos Orgânicos Voláteis/análise , Eliminação de Resíduos Líquidos/estatística & dados numéricos , Águas Residuárias/química , China , Monitoramento Ambiental/métodos , Humanos , Neoplasias/epidemiologia , Medição de Risco , Estações do AnoRESUMO
More and more research effort has been put into the development of affordable and high-efficiency wastewater reclamation technology for small communities. In this study, an integrated chemically enhanced primary treatment (CEPT), trickling filter (TF) and ultrafiltration (UF) process was developed with success. Coagulant produced from fly ash was used to enhance primary treatment, while trickling filter packed with coal cinder through four-layer structure without aeration was employed for further removal of COD and ammonium-nitrogen from the CEPT effluent. 95 and 88% removal of COD and ammonium were achieved, while total phosphorus (TP) and suspended solid (SS) were found to be removed completely at a coagulant dosage of 2.5 mL/L in the CEPT-TF-UF system. The product water can meet the standard of Reuse of Recycling Water for Urban Water Quality Standard for Urban Miscellaneous Water Consumption (GB/T 18920-2002, China).
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Filtração/instrumentação , Filtração/métodos , Reciclagem , Eliminação de Resíduos Líquidos/métodos , Carvão Mineral , Cinza de Carvão , Membranas Artificiais , Nitrogênio/química , Compostos de Amônio Quaternário/química , Estações do Ano , Fatores de Tempo , Purificação da ÁguaRESUMO
Background: Dermatitis is an important global health problem that not only affects social interaction and physical and mental health but also causes economic burden. Health problems or distress caused by dermatitis may be easily overlooked, and relevant epidemiological data are limited. Therefore, a better understanding of the burden of dermatitis is necessary for developing global intervention strategies. Methods: All data on dermatitis, including atopic dermatitis (AD), contact dermatitis (CD) and seborrhoeic dermatitis (SD), were obtained from the Global Burden of Disease 2019 (GBD2019) database. The extracted age-standardized incidence rates (ASIR) and disability-adjusted life-years (DALYs) rates (ASDR) data were analysed by stratification, including by sex, country or region, and sociodemographic index (SDI) indicators. Finally, we analysed the correlation between the global burden of dermatitis and socioeconomic development status. Results: According to the GBD 2019 estimate, the ASIR and ASDR for the three major types of dermatitis in 2019 were 5244.3988 (95% CI 4551.7244-5979.3176) per 100,000 person-years and 131.6711 (95% CI 77.5876-206.8796) per 100,000 person-years. The ASIR and ASDR of atopic dermatitis, contact dermatitis and seborrhoeic dermatitis are: Incidence (95%CI,per 100,000 person-years), 327.91 (312.76-343.67), 3066.04 (2405.38-3755.38), 1850.44 (1706.25- 1993.74); DALYs (95%CI, per 100,000 person-years), 99.69 (53.09-167.43), 28.06 (17.62-41.78), 3.93 (2.24-6.25). In addition, among the three dermatitis types, the greatest burden was associated with AD. According to the ASDR from 1990 to 2019, the burden of dermatitis has exhibited a slow downward trend in recent years. In 2019, the ASIR showed that the USA had the greatest burden, while the ASDR showed that Asian countries (such as Japan, Mongolia, Kazakhstan, and Uzbekistan) and some European countries (France, Estonia) had the greatest burden. According to SDI stratification and the three major dermatitis types, high ASIR and ASDR corresponded to high SDI areas (especially for AD). Conclusion: The burden of dermatitis is related to socioeconomic development status, especially for AD, which is positively correlated with the SDI. The results based on GBD2019 data are valuable for formulating policy, preventing and treating dermatitis and reducing the global burden of dermatitis.
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Dermatite Seborreica , Anos de Vida Ajustados por Deficiência , Humanos , Incidência , Anos de Vida Ajustados por Qualidade de Vida , Fatores SocioeconômicosRESUMO
The changes of skin tissue reflectance spectroscopy before and after being treated with the optical clearing agents of three different types of optical clearing within the wavelength rang of 400-1 000 nm, and the degree of changes in reflectance spectroscopy of each group skin during 0-60 min at 580 nm in vivo were real-time dynamically researched. The reflectance spectroscopy of skin tissue before and after being dealt by the optical clearing agents of glycerol, glucose and propylene glycol was measured using a USB-4000 fiber spectrophotometer at 0, 10, 20, 30, 40, 50 and 60 min. The results showed that the reflectance spectral intensity was distinctly decreased, but the reflectance was significantly increased gradually with the time prolonged. However, different optical clearing agents have different clearing progress. The relative decrease of reflectance of palm skin tissue before and after being dealt by the optical agents of 40% glycerol, 40% glucose and 40% propylene glycol during 10, 20, 30, 40, 50 and 60 min at the wavelength 580 nm is 5%, 7%, 9%, 10%, 11% and 12%, 9%, 13%, 16%, 19%, 21% and 22%, and 14%, 22%, 29%, 32%, 34% and 35%, respectively. The significant improvement in light transmittance and enhancement of light penetration through tissue was demonstrated for all solutions. The effect and processes of optical clearing of skin tissue is not only closely related to the choosing of the clearing agent type, but also related to the treatment time with the skin tissue. The clearing progress of different type optical clearing agent showed the order of 40% propylene glycol, 40% glucose and 40% glycerol.
Assuntos
Pele , Análise Espectral , Glucose/química , Glicerol/química , Humanos , Permeabilidade , Propilenoglicol/química , Espalhamento de RadiaçãoRESUMO
Soil column experiments were performed to investigate the behavior and characteristics of dissolved organic matter (DOM) during soil aquifer treatment (SAT), and to differentiate among the mechanisms responsible for the changes in the structural and functional properties of DOM during SAT. To determine the biological transformation of DOM, biodegradability tests using a biodegradation-column system were conducted. DOM was fractionated using XAD resins into 5 fractions: hydrophobic acid (HPO-A), hydrophobic neutral (HPO-N), transphilic acid (TPI-A), transphilic neutral (TPI-N) and hydrophilic fraction (HPI). Dissolved organic carbon (DOC) was removed by 70% during SAT, and the sorption and anaerobic biodegradation in SAT led to a DOC reduction of 27.4%. The significant changes in fluorescence properties of DOM were observed during SAT. However, the sorption and anaerobic biodegradation in SAT seemed to have no significant effect on the chemical structure of fluorescing constituents in DOM. The DOM fractions exhibited different changes in Fourier-transform infrared (FT-IR) spectra characteristics during SAT. Biodegradation resulted in the enrichment of aromatic structures and the decreased content of the oxygen-containing functional groups, such as CO and C-O, in DOM. On the other hand, the production of C-O and amide-2 functional groups occurred as a result of the sorption combined with anaerobic biodegradation in SAT.
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Compostos Orgânicos , Solo , Purificação da Água , Abastecimento de Água , Poluentes Químicos da ÁguaRESUMO
An anaerobic attached-growth bioreactor (AAGBR) of 3.52 L was operated for 510 days to treat sulfide-laden organic wastewater where nitrate and nitrite were introduced as electron acceptors. When the influent sulfide was kept at 200mg S(2-)-S/L and organic carbon was increased from 20 to 33.6 mg C/L, and the hydraulic retention time decreased from 41.4 to 2.67 h, the removal rates of sulfide and organic carbon reached 99.9% and 91.8% at the loading rates of 1800 mg S(2-)-S/(Ld) and 302.4 mg C/(Ld), respectively. Simultaneously, the introduced electron acceptors of nitrate and nitrite were, respectively, removed by 99.9% and 99.9% at the loading rates of 472.5 mg NO(3)(-)-N/(Ld) and 180 mg NO(2)(-)-N/(Ld). Inside the AAGBR, both autotrophic and heterotrophic denitrification processes were noted to take place. When the influent organic carbon was increased from 20 to 33.6 mg C/L, the nitrate and nitrite consumed for heterotrophic denitrification accounted for 27.3% and 48.5%, respectively. This simultaneous autotrophic and heterotrophic desulfurization-denitrification process has provided a demonstration of the possibility to eliminate sulfide and organic carbon with the presence of nitrate and nitrite.
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Nitratos/química , Nitritos/química , Sulfetos/isolamento & purificação , Enxofre/química , Anaerobiose , Reatores Biológicos , Microscopia Eletrônica de VarreduraRESUMO
Sediment microbial fuel cell (SMFC) and constructed wetlands with macrophytes have been independently employed for the removal of heavy metals from polluted aquatic ecosystems. Nonetheless, the coupling of macrophytes at the cathode of SMFCs for efficient and synchronous heavy metal removal and bioelectricity generation from polluted river sediment has not been fully explored. Therefore, a novel macrophyte biocathode SMFC (mSMFC) was proposed, developed, and evaluated for heavy metals/organics removal as well as bioelectricity generation in an urban polluted river. With macrophyte-integrated cathode, higher heavy metal removals of Pb 99.58%, Cd 98.46%, Hg 95.78%, Cr 92.60%, As 89.18%, and Zn 82.28% from the sediments were exhibited after 120 days' operation. Total chemical oxygen demand, total suspended solids, and loss on ignition reached 73.27%, 44.42 ± 4.4%, and 5.87 ± 0.4%, respectively. A maximum voltage output of 0.353 V, power density of 74.16 mW/m3, columbic efficiency of 19.1%, normalized energy recovery of 0.028 kWh/m3, and net energy production of 0.015 kWh/m3 were observed in the Lemna minor L. SMFC. Heavy metal and organic removal pathways included electrochemical reduction, precipitation and recovery, bioaccumulation by macrophyte from the surface water, and bioelectrochemical reduction in the sediment. This study established that mSMFC proved as an efficient system for the remediation of heavy metals Pb, Cd, Hg, Cr, As, and Zn, and TCOD in polluted rivers along with bioelectricity generation.
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Araceae/metabolismo , Fontes de Energia Bioelétrica , Eletrodos , Metais Pesados/metabolismo , Poluentes Químicos da Água/metabolismo , Biodegradação Ambiental , Análise da Demanda Biológica de Oxigênio , Ecossistema , Sedimentos Geológicos/química , Metais Pesados/análise , Rios , Poluentes Químicos da Água/análise , Áreas AlagadasRESUMO
The role of bromide ion in the trihalomethane (THM) formation and structure of dissolved organic matter (DOM) during chlorination of the secondary effluent taken from the Wenchang Wastewater Treatment Plant (Harbin, China) was investigated. DOM was fractionated using XAD resins into five fractions: hydrophobic acid (HPO-A), hydrophobic neutral (HPO-N), transphilic acid (TPI-A), transphilic neutral (TPI-N) and hydrophilic fraction (HPI). The patterns of individual THM species with increased bromide concentrations were similar for all DOM fractions. The THM speciation as well as halogen fraction for these five fractions followed similar trends with the Br(-)/Cl(2) ratio. Chlorination resulted in decreased ultraviolet (UV) absorbance across wavelengths from 250 to 280 nm for DOM fractions whether bromide ions existed or not, and bromide addition led to lower differential UV absorbance values. Fourier-transform infrared (FT-IR) results indicated that chlorination, whether bromide ions existed or not, resulted in the near elimination of aromatic CH and amide peaks, increased CO absorption intensity and occurrence of CO and CCl peaks for HPO-A, HPO-N, TPI-A and TPI-N. Furthermore, bromide addition in chlorination led to the occurrence of CBr peak for all four fractions.
Assuntos
Brometos/química , Cloretos/química , Substâncias Húmicas/análise , Trialometanos/química , Purificação da Água/métodos , SolubilidadeRESUMO
The ammonia removal performance of a hybrid electrooxidation and adsorption reactor (HEAR) is evaluated. The influences of current density, chloride concentration, and packing particles for ammonia removal in HEAR were investigated, and the performance of HEAR under serials circulation was studied. Results indicated that ammonia removal efficiency achieved around 70 % under the optimal condition after 30-min electrolysis. The optimal condition was determined as current density of 10 mA/cm2, Cl-/NH4+ molar ratio of 1.8, and modified zeolites as particles. The ammonia adsorption kinetic and adsorption isotherm on zeolites fitted well with second-order kinetic and Langmuir isotherm model, respectively. Adsorption amount of ammonia on zeolites sampled at 30-min electrolysis achieved 2.4 mg/L, higher than 1.9 mg/L of zeolites at 20-min electrolysis, indicating that electrooxidation coupled with adsorption led to simultaneous ammonia removal and zeolite regeneration in HEAR. No decrease of ammonia removal efficiency was observed over several cycles with the electrooxidation treatment. The presence of free chlorine indicating ammonia removal in HEAR was due to the combined influence by adsorption and indirect electrooxidation. These results showed that HEAR was a prospective alternative as a tertiary treatment for wastewater with low chloride ions.
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Amônia , Purificação da Água , Adsorção , Eletrólise , Cinética , Estudos Prospectivos , Águas Residuárias , ZeolitasRESUMO
Residual ammonia and pathogenic microorganisms restrict the reclamation and reuse of wastewater treatment plant (WWTP) effluent. An electrochemical system was developed for the simultaneous removal of ammonia and disinfection of actual WWTP effluent. The performance of the electrochemical process on synthetic wastewater at different chloride ion concentrations was also investigated. Results demonstrated that the optimal chloride concentration for ammonia and Escherichia coli (E. coli) removal was 250 mg/L. Successful disinfection of E. coli in actual effluent was achieved at 0.072 Ah/L, but the inverse S-type inactivation curve indicated that there was a competitive consumption of strong oxidants and chloramines working as another disinfectant. A higher electric charge (0.58 Ah/L) was required to simultaneously reduce E. coli and ammonia to levels that meet the reclamation requirements for WWTP effluent. At this electric charge, no trihalomethane, chlorate, or perchlorate in the system was observed, indicating the biological safety of this process. These results demonstrate the potential of this electrochemical process as a tertiary wastewater treatment process for WWTP effluent reclamation purposes.
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Amônia , Desinfecção/métodos , Nitrogênio , Águas Residuárias , Purificação da Água/métodos , Cloraminas , Cloretos , Desinfetantes , Escherichia coli , Oxidantes , Trialometanos/análise , Eliminação de Resíduos Líquidos/métodosRESUMO
Landfill leachate recirculation treatment process is a promising and economic way in northeast China due to the distinct season variation. In order to study the impact of recirculation on leachate production and its quality, two simulated sanitary landfill reactors, one with leachate recirculation and the other without, were placed outdoor in Harbin. The two-year experimental results indicated that leachate production was reduced by 86% with leachate recirculation and less or no facility for leachate treatment required. Recirculation could improve the leachate quality dramatically with lower COD, SS, NH4(+)-N and higher pH level. Recirculation also could enhance waste degradation and stabilization and improve the efficiency of landfill. This study confirmed that leachate recirculation was a very feasible way for on-site landfill leachate treatment in cold areas.
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Biodegradação Ambiental , Eliminação de Resíduos/métodos , Temperatura , Gerenciamento de Resíduos/métodos , Reatores Biológicos , China , Monitoramento Ambiental/métodos , Concentração de Íons de Hidrogênio , Chuva , Estações do Ano , Poluentes do Solo/análise , Movimentos da ÁguaRESUMO
In order to quantitatively identify sources of nitrate pollution in Beijing urban area and provide effective guidance for relevant departments to control the pollution of Beijing rivers, δ¹5N-NO3â» and δ¹8O-NO3â» isotope tracing method was used to analyze the composition of nitrogen and oxygen stable isotopes from nitrate in Beijing urban river. Besides, stable isotope mixing model was adopted to track nitrogen sources of nitrate in Beijing urban rivers and the contribution rates of respective pollution sources were evaluated. The results showed that: (1) NO3â»-N pollution was the main inorganic nitrogen pollution in Beijing rivers and pollution of downstream was more serious than that of upstream. (2) δ¹5N-NO3â» in Beijing urban surface rivers was in range of 6.26 per thousand-24.94 per thousand, while δ¹8O-NO3â» ranged -0.41 per thousand-11.74 per thousand; δ¹5N-NO3â» increased from upstream to downstream along the flow of the surface water. (3) The nitrate pollution composition of Beijing rivers could be gained from the stable isotope mixing model. The average contribution rates of manure and sewage, soil nitrate and atmospheric deposition were 61.2%, 31.5% and 7.3%, respectively.
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Monitoramento Ambiental , Nitratos/análise , Isótopos de Nitrogênio/análise , Isótopos de Oxigênio/análise , Rios/química , Poluentes Químicos da Água/análise , Pequim , Esterco , Modelos Teóricos , Esgotos , SoloRESUMO
OBJECTIVE: To investigate the inhibitory effects of triptolide on the migration, gene and protein expression of urokinase-type plasminogen activator (u-PA) of endothelial cells (ECs) cultured in vitro and to elucidate the anti-angiogenic mechanism of triptolide. METHODS: Human umbilical vein endothelial cells (HUVECs) were cultured in vitro and the passage 3 cells were treated with triptolide (0, 5, 10, 20, 30 microg/L). Three-dimensional culture system was used to assess the effect of triptolide on the migration of HUVECs. Real time quantitive reverse transcription polymerase chain reaction and immunohistochemical assay were applied to detect gene and protein expression of u-PA. RESULTS: Triptolide decreased the migration activity and suppressed the expression of u-PA of HUVECs at the gene and protein level. CONCLUSION: Triptolide could inhibit the migration of ECs by reducing the gene and protein expression of u-PA. These may contribute to an elucidation of the mechanism by which triptolide inhibits the angiogenesis.
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Inibidores da Angiogênese/farmacologia , Movimento Celular/efeitos dos fármacos , Diterpenos/farmacologia , Endotélio Vascular/citologia , Fenantrenos/farmacologia , Células Cultivadas , Compostos de Epóxi , Humanos , Recém-Nascido , RNA Mensageiro/biossíntese , RNA Mensageiro/genética , Veias Umbilicais/citologia , Ativador de Plasminogênio Tipo Uroquinase/biossíntese , Ativador de Plasminogênio Tipo Uroquinase/genéticaRESUMO
In order to remove the low turbidity present in surface water, a novel metal-polysilicate coagulant was used to treat the raw water taken from Tanjiang River in Guangdong Province. This study on the effects of Al/Fe molar ratio on the performance of a complex compound formed by polysilicic acid, aluminium and ferric salt (PAFS) showed that PAFS with Al/Fe ratio of 10:3 seemed to have the best coagulation performance in removing turbidity and color. Experimental results showed that under the conditions of polymerization time of 15 d, sedimentation time of 12 min, and pH of 6-8, PAFS with Al/Fe molar ratio of 10:3 had the best coagulation efficiency and lowest residual Al concentration. The turbidity decreased from 23.8 NTU to 3.23 NTU and the residual Al concentration was only 0.165 mg/L in the product water. It could be speculated that colloidal impurities and particulate Al were removed by adsorption bridging and electrical neutralization of long chain inorganic polymer coagulants.
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Alumínio/química , Coagulantes/química , Ferro/química , Polímeros/química , Silicatos/química , Purificação da Água/métodos , Água/química , Adsorção , Alumínio/análise , China , Cor , Floculação , Concentração de Íons de Hidrogênio , Ferro/análise , Fatores de Tempo , Abastecimento de Água/análise , Abastecimento de Água/normasRESUMO
Long-term performance is of primary concern when considering the commercialized use of an microbial fuel cell(MFC). The long-term stability of MFC was studied using dairy manure as substrate over a testing time of 171 d. The results showed that the MFC could efficiently recover electricity from dairy manure during the long-time run, and the average power density was 6. 77 Wm-3 +/- 2. 11 W m-3. On day 70, the polarization curve was measured, the open circuit voltage, internal resistance and maximum power density of MFC were 0. 874 V, 22. 1 omega and 14. 1 W.m -3, respectively. The 30-day TCOD removal decreased with increasing test time, and the CE during the 121-150 d period reached 17.5% +/-3.3%. Phylogenetic analyses revealed that the dominant microbial communities in anodic biofilm were Proteobacteria (45%) , Bacteroidetes (22%) , Firmicutes (17% ) and Actinobacteria (11% ). At genera level, the bacteria with electricity production and (or) cellulose degradation ability, such as Clostridium and Cellulomonas were the abundant taxa.
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Fontes de Energia Bioelétrica/microbiologia , Esterco , Animais , Bactérias/classificação , Biofilmes , Bovinos , Eletricidade , FilogeniaRESUMO
The emission of volatile organic compounds (VOCs) from wastewater treatment plants (WWTPs) is becoming an environmental issue of increasing concern. As biological treatment has been considered as one important approach for VOC removal, lab-scale batch experiments were conducted in this study to investigate the fates of four chlorinated hydrocarbons, including chloroform, carbon tetrachloride, trichloroethylene (TCE), and tetrachloroethylene (PERC), in the biological treatment processes with respect to the effects of aeration and sludge addition. The VOC concentrations in the phases of air, water, and sludge under four simulated treatment stages (the first sedimentation, the forepart and rear part of aerobic biological treatment, and the second sedimentation) were analyzed. The results were used to understand the three-phase partitioning of these compounds and to estimate their potentials for volatilization and biological sorption and degradation in these technologies with the concept of fugacity. It was observed that the VOCs were mainly present in the water phase through the experiments. The effects of aeration or sludge addition on the fates of these VOCs occurred but appeared to be relatively limited. The concentration distributions of the VOCs were well below the reported partitioning coefficients. It was suggested that these compounds were unsaturated in the air and sludge phases, enhancing their potentials for volatilization and biological sorption/degradation through the processes. However, the properties of these chlorinated VOCs such as the volatility, polarity, or even biodegradability caused by their structural characteristics (e.g., the number of chlorine, saturated or unsaturated) may represent more significant factors for their fates in the aerobic biological treatment processes. These findings prove the complication behind the current knowledge of VOC pollutions in WWTPs and are of help to manage the adverse impacts on the environment and public health by the VOCs from these particular sources.
Assuntos
Hidrocarbonetos Clorados/química , Esgotos/química , Compostos Orgânicos Voláteis/química , Aerobiose , Ar , Biodegradação Ambiental , Águas Residuárias/química , Purificação da Água/métodosRESUMO
Correlation between fractional, biodegradable and spectral characteristics of sludge extracellular polymeric substances (EPS) by different protocols has not been well established. This work extracted sludge EPS using alkaline extractants (NH4OH and formaldehyde + NaOH) and physical protocols (ultrasonication, heating at 80 °C or cation exchange resin (CER)) and then fractionated the extracts using XAD-8/XAD-4 resins. The alkaline extractants yielded more sludge EPS than the physical protocols. However, the physical protocols extracted principally the hydrophilic components which were readily biodegradable by microorganisms. The alkaline extractants dissolved additional humic-like substances from sludge solids which were refractory in nature. Different extraction protocols preferably extracted EPS with distinct fractional, biodegradable and spectral characteristics which could be applied in specific usages.
Assuntos
Biopolímeros/isolamento & purificação , Fracionamento Químico/métodos , Espaço Extracelular/química , Compostos Orgânicos/isolamento & purificação , Esgotos/química , Absorção/efeitos da radiação , Biodegradação Ambiental , Carboidratos/análise , Oxigênio/análise , Proteínas/análise , Solubilidade/efeitos da radiação , Espectrometria de Fluorescência , Espectroscopia de Infravermelho com Transformada de Fourier , Raios UltravioletaRESUMO
To differentiate the transformation of dissolved organic matter (DOM) during corrosion cell-Fenton (CCF) post-treatment, the leachate was separated into five fractions by XAD-8 and XAD-4 resins (hydrophilic fraction, HPI; hydrophobic acid, HPO-A; transphilic acid, TPI-A; hydrophobic neutral, HPO-N; transphilic neutral, TPI-N). UV-Vis spectroscopy and fluorescence spectroscopy were used for the degradation analysis. Experimental results showed that DOM in landfill leachate reduced 61.8% of dissolved organic carbon (DOC). Especially for HPO-A and HPO-N, with the removal ratios were up to 74.9% and 66.5%, respectively. The predominant portion in the effluent was HPI (comprising 60.1% of DOC). Spectral analyses showed that the leachate DOM was composed of abundant condensed ring aromatic compounds and humic substances, with the HPO-A was the highest aromatic fraction. The ratio of absorbance at 253 nm and 203 nm (E253/E203) was decreased in the order of HPO-A > HPO-N > TPI-A > TPI-N > HPI. The unsaturated conjugated structures were efficiently destroyed after the CCF treatment, and the functional groups such as carbonyl, amine were also eliminated. The main fluorophores in leachate fractions were in the region of aromatic protein-like and visible fulvic-like. The fluorescence intensity of peaks in each fraction decreased after CCF treatment, especially for the fulvic-like fluorescent substances. The results indicated that the CCF treatment was efficient to remove the hydrophobic fractions and reduce the complicacy of leachate effluent.