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1.
Mater Sci Eng C Mater Biol Appl ; 104: 109943, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31500025

RESUMO

The main objective of this work was to reduce the inhibitory effects of high contents of organics, ammonia, and heavy metals in an anaerobic buffled reactor (ABR), and to prevent the sludge wash-out using zeolites as media. In this work, a pilot scale of ABR with 8 compartments and a working volume of 14.4 L was used, and the last four ABR compartments were filled with a zeolite. The bioreactor was operated at HRTs of 3, 4, and 5 days, zeolite filling ratios of 10, 20, and 30%, and influent chemical oxygen demand (COD) concentrations of 10,000, 20,000, and 30,000 mg/L. The results obtained showed that the maximum removal efficiencies of COD and BOD5 reached 78 and 68%, respectively. The maximum removal was observed at a HRT of 5 days, a 30% medium filling ratio, and a COD of 10,000 mg/L. Increasing the filling ratio in the reactor increased the removal efficiencies of COD and BOD5 but increasing the concentration of the influent COD and decreasing HRT reduced the removal efficiency of the reactor. The initial BOD5/COD ratio was equal to 0.36, which increased by 46% when the medium filling ratio was elevated to 30%. The maximum biogas yield was 0.23 L/g of CODRemoved, and the specific methanogenic activity test verified the toxicity effect of the leachate on the gas-producer organisms. The results of scanning electronic microscopy and EDS showed that the zeolite medium immobilized the microorganisms and a biofilm was formed. Also the zeolite, as a well-known ion exchanger, decreased the concentrations of the major inhibitors (ammonia and heavy metals) and improved the reactor efficiency.


Assuntos
Anaerobiose/efeitos dos fármacos , Biodegradação Ambiental/efeitos dos fármacos , Zeolitas/química , Amônia/química , Biofilmes/efeitos dos fármacos , Biocombustíveis , Análise da Demanda Biológica de Oxigênio/métodos , Reatores Biológicos , Metais Pesados/química , Oxigênio/química , Esgotos/química , Eliminação de Resíduos Líquidos/métodos , Poluentes Químicos da Água/química
2.
Environ Monit Assess ; 191(7): 421, 2019 Jun 08.
Artigo em Inglês | MEDLINE | ID: mdl-31177336

RESUMO

Gaining rapid knowledge of dissolved organic matter (DOM) proves to be decisive for wastewater treatment plant operators in efforts to achieve good treatment efficiency in light of current legislation. DOM can be monitored by application of fluorescence spectroscopy both online and in real time in order to derive an assessment of DOM oxidation potential. This work presents an eco-friendly alternative method for measuring the soluble chemical oxygen demand (COD) in raw sewage by means of three-dimensional fluorescence spectroscopy. A peak-picking approach has been developed based on a previous parallel factor analysis (PARAFAC) model dedicated to Paris raw sewage. Fluorescence spectroscopy parameters were used to obtain a good prediction model of soluble COD (r2 = 0.799; p < 0.0001; n = 80) for raw sewage. The approach employed in this study serves as a guideline for purposes of implementing online wastewater monitoring and conducting environmentally friendly soluble COD measurements in the laboratory.


Assuntos
Análise da Demanda Biológica de Oxigênio/métodos , Monitoramento Ambiental/métodos , Águas Residuárias/química , Poluentes Químicos da Água/análise , Purificação da Água , Análise Fatorial , Substâncias Húmicas/análise , Esgotos/química , Espectrometria de Fluorescência/métodos
3.
Artigo em Inglês | MEDLINE | ID: mdl-30938573

RESUMO

A study was conducted to characterize the raw wastewater entering a modern cost effective municipal WWTP in Poland using two approaches; 1) a combination of modeling and carbonaceous oxygen demand (COD) fractionation using respirometric test coupled with model estimation (RT-ME) and 2) flocculation/filtration COD fractionation method combined with BOD measurements (FF-BOD). It was observed that the particulate fractions of COD obtained using FF-BOD method was higher than those estimated by RT-ME approach. Contrary to the above, the values of inert soluble fraction evaluated by FF-BOD method was significantly lower than RT-ME approach (2.4% and 3.9% respectively). Furthermore, the values for low colloidal and particulate fractions as well as soluble inert fractions were different than expected from a typical municipal wastewater. These observations suggest that even at low load (10% of the total wastewater treatment inflow), the industrial wastewater composition can significantly affect the characteristics of municipal wastewater which could also affect the performance and accuracy of respirometric tests. Therefore, in such cases, comparison of the respirometric tests with flocculation/filtration COD/BOD measurements are recommended. Oxygen uptake rate profile with settled wastewater and/or after coagulation-flocculation, however, could still be recommended as a "rapid" control method for monitoring/optimising modern cost-effective wastewater treatment plants.


Assuntos
Análise da Demanda Biológica de Oxigênio , Esgotos/química , Eliminação de Resíduos Líquidos/economia , Eliminação de Resíduos Líquidos/métodos , Águas Residuárias/química , Análise da Demanda Biológica de Oxigênio/métodos , Análise da Demanda Biológica de Oxigênio/normas , Calibragem , Compostos Inorgânicos de Carbono/química , Fracionamento Químico/métodos , Cidades , Análise Custo-Benefício , Monitoramento Ambiental/métodos , Monitoramento Ambiental/normas , Filtração , Floculação , Humanos , Oxigênio/química , Polônia , Purificação da Água/economia , Purificação da Água/métodos , Purificação da Água/normas
4.
J Environ Qual ; 48(2): 403-411, 2019 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-30951115

RESUMO

Sediment oxygen demand (SOD) plays a fundamental role in biological and chemical processes within the benthic layer of a water body. Land use, including agricultural land use, can affect SOD. However, a wide variety of approaches have been used for in situ SOD chamber construction and data collection, and modelers frequently use SOD values from the literature, without consideration of the differences in methods. Here, we review existing literature on SOD chambers (32 papers, 1974-2016), compare the differences between in situ and laboratory methods, evaluate the effects of in situ chamber mixing, and discuss common challenges associated with deployment. A cohesive in situ sealed chamber design for use with a multiparameter water-quality instrument is presented as an effort toward standardizing SOD methodology, an important consideration that may facilitate integration of SOD data sets among multiple research efforts.


Assuntos
Análise da Demanda Biológica de Oxigênio/métodos , Sedimentos Geológicos/química , Monitoramento Ambiental
5.
Sci Total Environ ; 666: 1089-1105, 2019 May 20.
Artigo em Inglês | MEDLINE | ID: mdl-30970475

RESUMO

Biochemical Oxygen Demand (BOD) is an indicator of organic pollution in freshwater bodies correlated to microbiological contamination. High BOD concentrations reduce oxygen availability, degrade aquatic habitats and biodiversity, and impair water use. High BOD loadings to freshwater systems are mainly coming from anthropogenic sources, comprising domestic and livestock waste, industrial emissions, and combined sewer overflows. We developed a conceptual model (GREEN+BOD) to assess mean annual current organic pollution (BOD fluxes) across Europe. The model was informed with the latest available European datasets of domestic and industrial emissions, population and livestock densities. Model parameters were calibrated using 2008-2012 mean annual BOD concentrations measured in 2157 European monitoring stations, and validated with other 1134 stations. The most sensitive model parameters were abatement of BOD by secondary treatment and the BOD decay exponent of travel time. The mean BOD concentrations measured in monitored stations was 2.10 mg O2/L and predicted concentrations were 2.54 mg O2/L; the 90th percentile of monitored BOD concentration was 3.51 mg O2/L while the predicted one was 4.76 mg O2/L. The model could correctly classify reaches for BOD concentrations classes, from high to poor quality, in 69% of cases. High overestimations (incorrect classification by 2 or more classes) were 2% and large underestimations were 5% of cases. Across Europe about 12% of freshwater network was estimated to be failing good quality due to excessive BOD concentrations (>5 mg O2/L). Dominant sources of BOD to freshwaters and seas were point sources and emissions from intensive livestock systems. Comparison with previous assessments confirms a decline of BOD pollution since the introduction of EU legislation regulating water pollution.


Assuntos
Análise da Demanda Biológica de Oxigênio/métodos , Monitoramento Ambiental , Água Doce/química , Oxigênio/análise , Poluição Química da Água/análise , Europa (Continente) , Modelos Teóricos , Estações do Ano
6.
Chemosphere ; 224: 707-715, 2019 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-30851522

RESUMO

In this work, dimensionally stable Ti/SnO2-RuO2 electrode is successfully prepared using thermal decomposition method for the electrocatalytic degradation of high-concentration industrial gallic acid (GA) effluent in detail. The surface morphology, crystal structure and element analysis of as-prepared Ti/SnO2-RuO2 electrode are characterized by scanning electron microscopy, X-ray diffraction and X-ray fluorescence spectrometer, respectively. In addition, cyclic voltammetry, polarization curve and accelerated life tests are exploited to investigate the electrocatalytic activity and stability of Ti/SnO2-RuO2 electrode. Orthogonal experiment shows that, among the factors (current density, temperature and initial pH), current density is pivotal parameter influencing the degradation efficiency of industrial GA effluent. COD removal and degradation efficiencies of GA effluent reach up to 76.9% and 80.1% after 6 h, respectively, at the optimal conditions (current density of 10 mA cm-2, pH 6 and 35 °C). The degradation of GA effluent follows pseudo-first-order reaction kinetics. This work provides an in-depth theoretical support and application of electrocatalytic technology to the treatment of high-concentration industrial GA effluent.


Assuntos
Análise da Demanda Biológica de Oxigênio/métodos , Ácido Gálico/química , Compostos de Rutênio/química , Compostos de Estanho/química , Titânio/química , Poluentes Químicos da Água/química , Purificação da Água/métodos , Eletrodos , Difração de Raios X
7.
Sci Total Environ ; 658: 449-456, 2019 Mar 25.
Artigo em Inglês | MEDLINE | ID: mdl-30579202

RESUMO

Ozone oxidation of organic micropollutants in biologically treated wastewater was investigated in pilot-scale after a high- and a low loaded activated sludge process. Higher ozone doses were required to remove organic micropollutants in the effluent wastewater from the high loaded activated sludge process. Further comparison of the micropollutant removal was based on normalized ozone doses, expressed as g O3/g DOC and g O3/g soluble COD (sCOD). A clear difference was noted for the two effluents when the micropollutant removal was normalized by DOC. This difference disappeared almost completely when the removal was linked to ozone doses normalized by sCOD. The dose-response curves for the organic micropollutants were practically linear in the removal range up to 95%. A linear prediction model was developed and compared with literature values to test the transferability of the obtained results. Results from this comparison indicated that the slope of the dose-response functions could be used to predict the removal efficiency of organic micropollutants at a third plant with an average uncertainty of 10%. The modeled ozone requirements were then set in relation to the COD concentrations in the discharged water from approximately 90 Swedish activated sludge treatment plants with and without nitrogen removal. This comparison highlighted the need for a well-functioning biological treatment for an effective ozone oxidation of organic micropollutants. The results in this study suggest that soluble COD should be further explored for design and modeling of ozone oxidation of organic micropollutants in biologically treated wastewater.


Assuntos
Análise da Demanda Biológica de Oxigênio/métodos , Compostos Orgânicos/análise , Ozônio/química , Águas Residuárias/análise , Poluentes Químicos da Água/análise , Oxirredução , Eliminação de Resíduos Líquidos/métodos
8.
Ecotoxicol Environ Saf ; 152: 55-60, 2018 May 15.
Artigo em Inglês | MEDLINE | ID: mdl-29407782

RESUMO

Antipsychotic (AP) drugs are becoming accumulated in terrestrial and aqueous resources due to their actual consumption. Thus, the search of methods for assessing the contamination load of these drugs is mandatory. The COD is a key parameter used for monitoring water quality upon the assessment of the effect of polluting agents on the oxygen level. Thus, the present work aims to assess the chemical oxygen demand (COD) levels of several typical and atypical antipsychotic drugs in order to obtain structure-activity relationships. It was implemented the titrimetric method with potassium dichromate as oxidant and a digestion step of 2h, followed by the measurement of remained unreduced dichromate by titration. After that, an automated sequential injection analysis (SIA) method was, also, used aiming to overcome some drawbacks of the titrimetric method. The results obtained showed a relationship between the chemical structures of antipsychotic drugs and their COD values, where the presence of aromatic rings and oxidable groups give higher COD values. It was obtained a good compliance between the results of the reference batch procedure and the SIA system, and the APs were clustered in two groups, with the values ratio between the methodologies, of 2 or 4, in the case of lower or higher COD values, respectively. The SIA methodology is capable of operating as a screening method, in any stage of a synthetic process, being also more environmentally friendly, and cost-effective. Besides, the studies presented open promising perspectives for the improvement of the effectiveness of pharmaceutical removal from the waste effluents, by assessing COD values.


Assuntos
Antipsicóticos/análise , Análise da Demanda Biológica de Oxigênio/métodos , Águas Residuárias/análise , Poluentes Químicos da Água/análise , Antipsicóticos/química , Oxirredução , Oxigênio/análise , Relação Estrutura-Atividade , Titulometria , Eliminação de Resíduos Líquidos , Poluentes Químicos da Água/química , Qualidade da Água
9.
J Environ Manage ; 204(Pt 1): 221-229, 2017 Dec 15.
Artigo em Inglês | MEDLINE | ID: mdl-28888204

RESUMO

High total dissolved solids (TDS) wastewater containing high amounts of organics with toxic and recalcitrant characteristics is a major concern in some petrochemical industries. This study was designed to evaluate a novel electrokinetic process for chemical oxygen demand (COD) removal. The removal of COD was carried out in some batch experiments in lab scale and effect of experimental factors such as the pH, current intensity, time, electrodes distances and TDS on the COD removal was evaluated. Also scale-up of the process was done in order to evaluate energy consumption. The obtained findings indicated that best conditions for COD removal were achieved in pH 5, current intensity of 0.5 A and electrodes distance of 2 cm. Pseudo-first-order kinetic model with rate constant of 0.0093 min-1 and significant coefficient of correlation (R2) 0.948 was the best fitted with experimental results. Energy consumption was 32 KWh.m-3 while 80 fold scaling up the reactor resulted in lower energy consumption of 2.1 KWh.m-3. Biodegradability improvement confirmed by BOD5/COD, average oxidation state (AOS) and carbon oxidation state (COS) indicators, Also GC chromatogram of the raw and treated wastewater showed removal and/or degradation of recalcitrant organics to more degradable and simpler compounds.


Assuntos
Análise da Demanda Biológica de Oxigênio/métodos , Cloreto de Sódio/química , Águas Residuárias/química , Biodegradação Ambiental , Eletrodos , Resíduos Industriais , Oxirredução
10.
Sci Rep ; 7(1): 5426, 2017 07 14.
Artigo em Inglês | MEDLINE | ID: mdl-28710391

RESUMO

The microalgae-based technology has been developed to reduce biogas slurry nutrients and upgrade biogas simultaneously. In this work, five microalgal strains named Chlorella vulgaris, Scenedesmus obliquus, Selenastrum capricornutum, Nitzschia palea, and Anabaena spiroides under mono- and co-cultivation were used for biogas upgrading. Optimum biogas slurry nutrient reduction could be achieved by co-cultivating microalgae (Chlorella vulgaris, Scenedesmus obliquus, and Nitzschia palea) with fungi using the pelletization technology. In addition, the effects of different ratio of mixed LED light wavelengths applying mixed light-emitting diode during algae strains and fungi co-cultivation on CO2 and biogas slurry nutrient removal efficiency were also investigated. The results showed that the COD (chemical oxygen demand), TN (total nitrogen), and TP (total phosphorus) removal efficiency were 85.82 ± 5.37%, 83.31 ± 4.72%, and 84.26 ± 5.58%, respectively at red: blue = 5:5 under the co-cultivation of S. obliquus and fungi. In terms of biogas upgrading, CH4 contents were higher than 90% (v/v) for all strains, except the co-cultivation with S. obliquus and fungi at red: blue = 3:7. The results indicated that co-cultivation of microalgae with fungi under mixed light wavelengths treatments was most successful in nutrient removal from wastewater and biogas upgrading.


Assuntos
Biocombustíveis , Análise da Demanda Biológica de Oxigênio/métodos , Microalgas/metabolismo , Nitrogênio/metabolismo , Fósforo/metabolismo , Anabaena/crescimento & desenvolvimento , Anabaena/metabolismo , Biomassa , Dióxido de Carbono/metabolismo , Chlorella vulgaris/crescimento & desenvolvimento , Chlorella vulgaris/metabolismo , Fungos/crescimento & desenvolvimento , Fungos/metabolismo , Microalgas/crescimento & desenvolvimento , Técnicas Microbiológicas/métodos , Scenedesmus/crescimento & desenvolvimento , Scenedesmus/metabolismo
11.
Hypertension ; 70(1): 75-84, 2017 07.
Artigo em Inglês | MEDLINE | ID: mdl-28584018

RESUMO

This randomized, double-blind, placebo-controlled study was designed to explore the effects of exposure to very high altitude hypoxia on vascular wall properties and to clarify the role of renin-angiotensin-aldosterone system inhibition on these vascular changes. Forty-seven healthy subjects were included in this study: 22 randomized to telmisartan (age, 40.3±10.8 years; 7 women) and 25 to placebo (age, 39.3±9.8 years; 7 women). Tests were performed at sea level, pre- and post-treatment, during acute exposure to 3400 and 5400-m altitude (Mt. Everest Base Camp), and after 2 weeks, at 5400 m. The effects of hypobaric hypoxia on mechanical properties of large arteries were assessed by applanation tonometry, measuring carotid-femoral pulse wave velocity, analyzing arterial pulse waveforms, and evaluating subendocardial oxygen supply/demand index. No differences in hemodynamic changes during acute and prolonged exposure to 5400-m altitude were found between telmisartan and placebo groups. Aortic pulse wave velocity significantly increased with altitude (P<0.001) from 7.41±1.25 m/s at sea level to 7.70±1.13 m/s at 3400 m and to 8.52±1.59 m/s at arrival at 5400 m (P<0.0001), remaining elevated during prolonged exposure to this altitude (8.41±1.12 m/s; P<0.0001). Subendocardial oxygen supply/demand index significantly decreased with acute exposure to 3400 m: from 1.72±0.30 m/s at sea level to 1.41±0.27 m/s at 3400 m (P<0.001), remaining significantly although slightly less reduced after reaching 5400 m (1.52±0.33) and after prolonged exposure to this altitude (1.53±0.25; P<0.001). In conclusion, the acute exposure to hypobaric hypoxia induces aortic stiffening and reduction in subendocardial oxygen supply/demand index. Renin-angiotensin-aldosterone system does not seem to play any significant role in these hemodynamic changes. CLINICAL TRIAL REGISTRATION: URL: https://www.clinicaltrialsregister.eu/. Unique identifier: 2008-000540-14.


Assuntos
Doença da Altitude , Aorta , Benzimidazóis , Benzoatos , Sistema Renina-Angiotensina , Rigidez Vascular , Adulto , Doença da Altitude/complicações , Doença da Altitude/metabolismo , Doença da Altitude/fisiopatologia , Doença da Altitude/prevenção & controle , Bloqueadores do Receptor Tipo 1 de Angiotensina II/administração & dosagem , Bloqueadores do Receptor Tipo 1 de Angiotensina II/farmacocinética , Aorta/efeitos dos fármacos , Aorta/metabolismo , Aorta/fisiopatologia , Benzimidazóis/administração & dosagem , Benzimidazóis/farmacocinética , Benzoatos/administração & dosagem , Benzoatos/farmacocinética , Disponibilidade Biológica , Análise da Demanda Biológica de Oxigênio/métodos , Feminino , Hemodinâmica/efeitos dos fármacos , Hemodinâmica/fisiologia , Humanos , Masculino , Manometria/métodos , Pessoa de Meia-Idade , Análise de Onda de Pulso/métodos , Sistema Renina-Angiotensina/efeitos dos fármacos , Sistema Renina-Angiotensina/fisiologia , Telmisartan , Resultado do Tratamento , Rigidez Vascular/efeitos dos fármacos , Rigidez Vascular/fisiologia
12.
Biotechnol Bioeng ; 114(10): 2245-2252, 2017 10.
Artigo em Inglês | MEDLINE | ID: mdl-28600892

RESUMO

This study proposed a novel free ammonia (FA, i.e., NH3 ) pretreatment technology to enhance anaerobic methane production from primary sludge for the first time. The solubilization of primary sludge was substantially enhanced following 24 h FA pretreatment (250-680 mg NH3 -N/L), by which the release of soluble chemical oxygen demand (SCOD) (i.e., 0.4 mg SCOD/mg VS added; VS: volatile solids) was approximately 10 times as much as that without pretreatment (i.e., 0.03 mg SCOD/mg VS added). Then, biochemical methane potential (BMP) tests demonstrated that FA pretreatment of 250-680 mg NH3 -N/L was capable of enhancing anaerobic methane production while the digestion time was more than 7 days. Model based analysis indicated that the improved anaerobic methane production was due to an increased biochemical methane potential (B0 ) of 8-17% (i.e., from 331 to 357-387 L CH4 /kg VS added), with the highest B0 achieved at 420 mg NH3 -N/L pretreatment. However, FA pretreatment of 250-680 mg NH3 -N/L decreased hydrolysis rate (k) by 24-38% compared with control (i.e., from 0.29 d-1 to 0.18-0.22 d-1 ), which explained the lower methane production over the first 7 days' digestion period. Economic analysis and environmental evaluation demonstrated that FA pretreatment technology was environmentally friendly and economically favorable. Biotechnol. Bioeng. 2017;114: 2245-2252. © 2017 Wiley Periodicals, Inc.


Assuntos
Amônia/química , Bactérias Anaeróbias/fisiologia , Metano/metabolismo , Oxigênio/metabolismo , Esgotos/química , Esgotos/microbiologia , Águas Residuárias/microbiologia , Anaerobiose/fisiologia , Análise da Demanda Biológica de Oxigênio/métodos , Reatores Biológicos/microbiologia , Proliferação de Células/fisiologia , Solubilidade , Purificação da Água/métodos
13.
Water Sci Technol ; 75(11-12): 2527-2537, 2017 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-28617271

RESUMO

The impacts of land use/cover change (LUCC) on hydrological processes and water resources are mainly reflected in changes in runoff and pollutant variations. Low impact development (LID) technology is utilized as an effective strategy to control urban stormwater runoff and pollution in the urban catchment. In this study, the impact of LUCC on runoff and pollutants in an urbanizing catchment of Guang-Ming New District in Shenzhen, China, were quantified using a dynamic rainfall-runoff model with the EPA Storm Water Management Model (SWMM). Based on the simulations and observations, the main objectives of this study were: (1) to evaluate the catchment runoff and pollutant variations with LUCC, (2) to select and optimize the appropriate layout of LID in a planning scenario for reducing the growth of runoff and pollutants under LUCC, (3) to assess the optimal planning schemes for land use/cover. The results showed that compared to 2013, the runoff volume, peak flow and pollution load of suspended solids (SS), and chemical oxygen demand increased by 35.1%, 33.6% and 248.5%, and 54.5% respectively in a traditional planning scenario. The assessment result of optimal planning of land use showed that annual rainfall control of land use for an optimal planning scenario with LID technology was 65%, and SS pollutant load reduction efficiency 65.6%.


Assuntos
Análise da Demanda Biológica de Oxigênio/métodos , Planejamento de Cidades , Água Doce/química , Poluição Química da Água/prevenção & controle , China , Hidrologia , Modelos Teóricos
14.
Bioengineered ; 8(5): 446-450, 2017 Sep 03.
Artigo em Inglês | MEDLINE | ID: mdl-28095107

RESUMO

Petroleum wastewater samples from oil refinery and oil exploration site were treated by hyper phenol-tolerant Bacillus cereus (AKG1 and AKG2) in laboratory-scale batch process to assess their bioremediation efficacy. Quality of the treated wastewater samples were analyzed in terms of removal of chemical oxygen demand (COD), total organic carbon (TOC) and ammonium nitrogen content, and improvement of biological oxygen demand (BOD). Adaptation of these bacteria to the toxic environment through structural changes in their cell membranes was also highlighted. Among different combinations, the co-culture of AKG1 and AKG2 showed the best performance in degrading the wastewater samples.


Assuntos
Bacillus/classificação , Bacillus/fisiologia , Reatores Biológicos/microbiologia , Petróleo/microbiologia , Águas Residuárias/microbiologia , Poluentes Químicos da Água/metabolismo , Purificação da Água/métodos , Bacillus/efeitos dos fármacos , Técnicas de Cultura Celular por Lotes/métodos , Biodegradação Ambiental , Análise da Demanda Biológica de Oxigênio/métodos , Proliferação de Células/fisiologia , Hidrocarbonetos Aromáticos/isolamento & purificação , Hidrocarbonetos Aromáticos/metabolismo , Fenol/administração & dosagem , Projetos Piloto , Especificidade da Espécie , Poluentes Químicos da Água/isolamento & purificação
15.
Enzyme Microb Technol ; 98: 43-51, 2017 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-28110663

RESUMO

We investigated the use of one- and two-mediator systems in amperometric BOD biosensors (BOD, biochemical oxygen demand) based on the yeast Debaryomyces hansenii. Screening of nine mediators potentially capable of electron transfer - ferrocene, 1,1'-dimethylferrocene, ferrocenecarboxaldehyde, ferroceneacetonitrile, neutral red, 2,6-dichlorophenolindophenol, thionine, methylene blue and potassium ferricyanide - showed only ferrocene and neutral red to be efficient electron carriers for the eukaryotes studied. Two-mediator systems based on combinations of the investigated compounds were used to increase the efficiency of electron transfer. The developed two-mediator biosensors exceeded their one-mediator analogs by their characteristics. The most preferable two-mediator system for developing a BOD biosensor was a ferrocene-methylene blue combination that ensured a satisfactory long-time stability (43 days), selectivity, sensitivity (the lower limit of the determined BOD5 concentrations, 2.5mg О2/dm3) and speed (assay time for one sample, not greater than 10min) of BOD determination. Analysis of water samples showed that the use of a ferrocene-methylene blue two-mediator system and the yeast D. hansenii enabled registration of data that highly correlated with the results of the standard method (R=0.9913).


Assuntos
Análise da Demanda Biológica de Oxigênio/métodos , Técnicas Biossensoriais/métodos , Debaromyces/metabolismo , Transporte de Elétrons , Compostos Ferrosos/metabolismo , Indicadores e Reagentes/metabolismo , Metalocenos , Azul de Metileno/metabolismo , Vermelho Neutro/metabolismo , Água/análise
16.
Enzyme Microb Technol ; 98: 52-57, 2017 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-28110664

RESUMO

Biochemical oxygen demand (BOD) sensors based on Zr (IV)-loaded collagen fiber (ZrCF), a novel material with great porous structure, were developed. This novel material shows adsorbability by microorganisms. Saccharomyces cerevisiae and Escherichia coli were used for the construction of BOD sensors. Factors affecting BOD sensor performance were examined. The ZrCF-based BOD sensor showed different sensitivities and linear response ranges with different biofilm densities. The amount of microorganisms strongly affected the performance of the BOD sensor. Poor permeability of previously reported immobilization carriers were greatly circumvented by ZrCF. The service life of the ZrCF-based BOD sensor was more than 42 days. The immobilized microorganisms can be stored for more than 6 months under 4°C in PB solution. There was good correlation between the results of the sensor method and the standard 5-day BOD method in the determination of pure organic substrates and real water samples.


Assuntos
Análise da Demanda Biológica de Oxigênio/métodos , Técnicas Biossensoriais/métodos , Biofilmes , Células Imobilizadas/metabolismo , Colágeno , Escherichia coli/metabolismo , Concentração de Íons de Hidrogênio , Saccharomyces cerevisiae/metabolismo , Salinidade , Temperatura Ambiente , Águas Residuárias/análise , Poluentes Químicos da Água/análise , Zircônio
17.
Appl Biochem Biotechnol ; 181(2): 710-724, 2017 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-27723011

RESUMO

In this work, gas dispersion in a two-phase partitioning bioreactor is analyzed by calculating volumetric oxygen mass transfer coefficient which is modeled using a commercial computational fluid dynamics (CFD), code FLUENT 6.2. Dispersed oxygen bubbles dynamics is based on standard "k-ε" Reynolds-averaged Navier-Stokes (RANS) model. This paper describes a three-dimensional CFD model coupled with population balance equations (PBE) in order to get more confirming results of experimental measurements. Values of k L a are obtained using dynamic gassing-out method. Using the CFD simulation, the volumetric mass transfer coefficient is calculated based on Higbie's penetration theory. Characteristics of mass transfer coefficient are investigated for five configurations of impeller and three different aeration flow rates. The pitched six blade type, due to the creation of downward flow direction, leads to higher dissolved oxygen (DO) concentrations, thereby, higher values of k L a compared with other impeller compositions. The magnitude of dissolved oxygen percentage in the aqueous phase has direct correlation with impeller speed and any increase of the aeration magnitude leads to faster saturation in shorter periods of time. Agitation speeds of 300 to 800 rpm are found to be the most effective rotational speeds for the mass transfer of oxygen in two-phase partitioning bioreactors (TPPB).


Assuntos
Reatores Biológicos , Meios de Cultura/química , Gases/química , Modelos Químicos , Oxigênio/química , Reologia/métodos , Análise da Demanda Biológica de Oxigênio/métodos , Transferência de Energia
18.
Biotechnol Bioeng ; 113(11): 2377-85, 2016 11.
Artigo em Inglês | MEDLINE | ID: mdl-27144731

RESUMO

The effect of anaerobic hydrolysis of particulate COD (pCOD) on biological phosphorous removal in extended anaerobic condition was investigated through (i) sequencing batch reactors (SBR)s with anaerobic hydraulic retention time (HRT) of 0.8, 2, and 4 h; (ii) batch tests using biomass from a full scale biological nutrient removal (BNR) plant; and (iii) activated sludge modeling (BioWin 4.1 simulation). The results from long-term SBRs operation showed that phosphorus removal was correlated to the ratio of filtered COD (FCOD) to total phosphorus (TP) in the influent. Under conditions with low FCOD/TP ratio (average of 20) in the influent, extending anaerobic HRT to 4 h in the presence of pCOD did not significantly improve overall phosphorous removal. During the period with high FCOD/TP ratio (average of 37) in the influent, all SBRs removed phosphorous completely, and the long anaerobic HRT did not have negative effect on overall phosphorous removal. The batch tests also showed that pCOD at different concentration during 4 h test did not affect the rate of anaerobic phosphorus release. The rate of anaerobic hydrolysis of pCOD was significantly low and extending the anaerobic HRT was ineffective. The simulation (BioWin 4.1) of SBRs with low influent FCOD/TP ratio showed that the default kinetics of anaerobic hydrolysis in ASM2d overestimated phosphorous removal in the SBRs (high anaerobic hydrolysis of pCOD). The default anaerobic hydrolysis rate in BioWin 4.1 (ten times lower) could produce similar phosphorous removal to that in the experiment. Results showed that the current kinetics of anaerobic hydrolysis in ASM2d could lead to considerable error in predicting phosphorus removal in processes with extended anaerobic HRT. Biotechnol. Bioeng. 2016;113: 2377-2385. © 2016 Wiley Periodicals, Inc.


Assuntos
Modelos Biológicos , Oxigênio/metabolismo , Material Particulado/metabolismo , Esgotos/microbiologia , Poluentes Químicos da Água/metabolismo , Purificação da Água/métodos , Anaerobiose , Biodegradação Ambiental , Análise da Demanda Biológica de Oxigênio/métodos , Reatores Biológicos/microbiologia , Simulação por Computador , Hidrólise , Fósforo , Poluentes Químicos da Água/isolamento & purificação
19.
Water Environ Res ; 88(3): 210-6, 2016 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-26931531

RESUMO

An improved method was used to determine chemical oxygen demand (COD) as a measure of organic content in water samples containing high chloride content. A contour plot of COD percent error in the Cl(-)-Cl(-):COD domain showed that COD errors increased with Cl(-):COD. Substantial errors (>10%) could occur in low Cl(-):COD regions (<300) for samples with low (<10 g/L) and high chloride concentrations (>25 g/L). Applying the method to flowback water samples resulted in COD concentrations ranging in 130 to 1060 mg/L, which were substantially lower than the previously reported values for flowback water samples from Marcellus Shale (228 to 21 900 mg/L). It is likely that overestimations of COD in the previous studies occurred as result of chloride interferences. Pretreatment with mercuric sulfate, and use of a low-strength digestion solution, and the contour plot to correct COD measurements are feasible steps to significantly improve the accuracy of COD measurements.


Assuntos
Análise da Demanda Biológica de Oxigênio/métodos , Análise da Demanda Biológica de Oxigênio/normas , Brometos , Cloretos , Colorimetria , Compostos de Mercúrio , Ácidos Ftálicos , Salinidade , Sulfatos
20.
Sensors (Basel) ; 16(1)2016 Jan 15.
Artigo em Inglês | MEDLINE | ID: mdl-26784197

RESUMO

Microbial fuel cells represent an innovative technology which allow simultaneous waste treatment, electricity production, and environmental monitoring. This study provides a preliminary investigation of the use of terrestrial Single chamber Microbial Fuel Cells (SMFCs) as biosensors. Three cells were created using Andean soil, each one for monitoring a BOD concentration of synthetic washed rice wastewater (SRWW) of 10, 100, and 200 mg/L for SMFC1, SMFC2 and SMFC3, respectively. The results showed transient, exponential, and steady stages in the SMFCs. The maximum open circuit voltage (OCV) peaks were reached during the elapsed time of the transient stages, according to the tested BOD concentrations. A good linearity between OCV and time was observed in the increasing stage. The average OCV in this stage increased independently of the tested concentrations. SMFC1 required less time than SMFC2 to reach the steady stage, suggesting the BOD concentration is an influencing factor in SMFCs, and SMFC3 did not reach it. The OCV ratios were between 40.6-58.8 mV and 18.2-32.9 mV for SMFC1 and SMFC2. The reproducibility of the SMFCs was observed in four and three cycles for SMFC1 and SMFC2, respectively. The presented SMFCs had a good response and reproducibility as biosensor devices, and could be an alternative for environmental monitoring.


Assuntos
Fontes de Energia Bioelétrica , Análise da Demanda Biológica de Oxigênio/métodos , Técnicas Biossensoriais/métodos , Oryza/química , Águas Residuárias/química , Modelos Lineares , Reprodutibilidade dos Testes
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