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1.
Chemosphere ; 254: 126781, 2020 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-32335438

RESUMO

In this work acid-treated activated carbon was developed from rice husk, and it was used as raw material for Capacitive deionization (CDI) electrodes. The prepared acid treated rice husk waste biomass activated carbon (RHWBAC) electrode was used for the electrosorption of Cr(VI) from the aqueous medium. This RHWBAC electrode shows maximum electrosorption capacity was 2.8316 mg g-1 of initial feed concentration 100 mg L-1 at 1.2 V. The result shows that the electrosorption method follows Redlich Peterson isotherm, Langmuir isotherm model, and Pseudo first order kinetic model. The computational fluid dynamics (CFD) analysis of square CDI cell design shows that the stagnant regions decreases by increasing the flow rate of feed. The present work concluded that the RHWBAC could be capable electrode material for Cr(VI) sorption from low concentrated aqueous feed.


Assuntos
Cromo/química , Poluentes Químicos da Água/química , Biomassa , Carvão Vegetal , Eletrodos , Hidrodinâmica , Cinética , Oryza , Água , Purificação da Água/métodos
2.
Environ Sci Pollut Res Int ; 27(12): 14007-14018, 2020 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-32036530

RESUMO

Iron catalyst supported over magnesium oxide had been synthesized with different percentages of Fe, i.e., 0.5, 1, and 5% employing the method of impregnation. These fabricated catalysts were used to grow carbon nanotubes (CNTs) using a chemical vapor deposition (CVD) method in the CVD reactor. The 5% Fe/MgO catalyst showed the maximum growth of CNTs. The synthesized novel CNTs (5Fe-CNTs) were investigated for their adsorption capabilities for the removal of parts per million levels of hexavalent chromium from electroplating effluent. The 5Fe-CNTs were characterized by field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), Raman spectroscopy, thermogravimetric analysis (TGA), and Zeta analyzer. The 5Fe-CNTs showed remarkable adsorption capacity of 63.3 mg g-1 toward Cr(VI) in water. The effects of various operating conditions on the removal of Cr(VI) from wastewater have been evaluated. Kinetic and thermodynamic studies were performed, and it was observed that the experimental data is in best agreement with pseudo-second-order kinetics. Besides the synthesized CNTs exhibited good recyclability for adsorbing Cr(VI) as even after 3 adsorption cycles, the adsorption capacity was reduced by less than 10%.


Assuntos
Nanotubos de Carbono , Poluentes Químicos da Água/análise , Purificação da Água , Adsorção , Cromo/análise , Galvanoplastia , Cinética , Águas Residuárias
3.
Environ Sci Pollut Res Int ; 27(12): 13844-13854, 2020 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-32036537

RESUMO

Magnetic magnesium ferrite (MgFe2O4) nanoparticles (MMFNPs) were synthesized by employing the sol-gel method. These nanoparticles were ultrasonically decorated onto the multi-walled carbon nanotubes (MWCNTs) to produce magnetic magnesium ferrite nanocomposites (MMFNCs). The as-prepared materials were investigated for their capability to treat wastewater loaded with heavy metals. The synthesized nanocomposites were characterized by field emission scanning electron microscopy, transmission electron microscopy, X-ray diffraction, Fourier transmission infrared spectroscopy, Raman spectroscopy, thermogravimetric analysis, and zeta analyzer. Besides, the effect of the environmental chemistry of the solution was determined by varying the critical parameters. The adsorption isotherm of Cr(VI) adsorption onto the as-synthesized MMFNC best fitted the Langmuir adsorption isotherm model. The high adsorption capacity of 175.43 mg/g was achieved at a temperature of 40 °C under optimized conditions. Due to the magnetic nature of MMFNC, they are easily recoverable from the aqueous solution making them cost-friendly. Even after seven consecutive adsorption-desorption cycles, the MMFNC presented an efficiency loss of less than 20% for the removal of Cr(VI) ions. The presented development method offers prospects in developing a highly effective magnetic adsorbent for heavy metal removal from wastewater.


Assuntos
Nanotubos de Carbono , Poluentes Químicos da Água/análise , Adsorção , Cromo , Compostos Férricos , Cinética , Compostos de Magnésio , Fenômenos Magnéticos , Águas Residuárias
4.
Chemosphere ; 249: 125982, 2020 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-32078848

RESUMO

Global pollution from excessive pesticide use has become a serious environmental and public health problem. The aim of the study was to optimize the fungal mediated simultaneous removal of carbofuran and carbaryl from soil. Carb-PV5 strain was isolated from contaminated soil following enrichment culture technique; based on 18S rRNA sequencing, strain was identified as Acremonium sp. (MK514615); Field Emission Scanning Electron Microscopic analysis reflected its morphology. Towards the development of bioaugmentation strategy for the bioremediation of carbamate-contaminated soil, the process parameters were optimized employing Central Composite Rotatable Method. The experimental studies were performed in the range of biomass (0.2-0.6 g kg-1), temperature (23-33 °C), pH (6-9) and moisture (10-30%). The degradation rate parameters, k and t1/2 were determined to as 0.475, 0.325 d-1 and 5.39, 2.1 d with the corresponding r2 of 0.9491, 0.9964 for zero and first order, respectively. The cube root growth kinetic constant k of Acremonium sp. varied from 0.0469 to 0.0512 (g1/3 L-1/3 h-1) and 0.0378 to 0.0415 (g1/3 L-1/3 h-1) for carbofuran and carbaryl, respectively. To confirm the model appropriacy and sustainability of the optimization procedure, bioremediation experiments were conducted onto real carbamate-contaminated soils. UPLC and GCMS analysis confirmed the successful removal of carbamates. The current study presents the first report on the bioaugmentation studies carried out on the mixed carbamate contaminated soil using newly isolated Acremonium sp.


Assuntos
Biodegradação Ambiental , Carbamatos , Poluentes do Solo/análise , Acremonium , Carbaril , Carbofurano , Praguicidas , Solo , Microbiologia do Solo , Temperatura
5.
Environ Pollut ; 261: 114073, 2020 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-32078877

RESUMO

The intensive application of type-II pyrethroid worldwide in agricultural and residential practices potentially contributes to soil and water pollution, raising various concerns about environmental and public health. In the present study, robust fungus (strain PYR-P2) with high pyrethroids degradation potential was isolated from pesticide-contaminated soil. The strain was identified based on morphology and molecular characteristics, as Aspergillus sp. The screening of the transforming ability of strain PYR-P2 was evaluated in minimal salt media (MSM), where the fungus utilized up to 500 mg L-1 of pyrethroid mixture (cypermethrin (CYP), cyfluthrin (CYF), cyhalothrin (CYH)). With this in view, central composite design (CCD) with three independent variables (pH, temperature, and initial concentration) was employed to identify the optimal conditions for achieving maximum pyrethroid removal. Under optimal conditions, strain PYR-P2 was implemented for the bioaugmentation studies in natural and sterile soil (NS/SS) systems spiked with pyrethroid (single and mixture) at a concentration of 100 mg kg-1. The highest pyrethroid removal percentages were observed in fungally augmented NS, accompanied by a decrease in pyrethroid half-life (t1/2). Herein, the observed half-life (t1/2) of pyrethroids in the fungally augmented NS varied between 1.48 and 2.69 d, with equally good values recorded in SS as 1.65-3.10 d. Taken together, the mycoremediation study employing fungal (strain PYR-P2) augmentation under optimized conditions represents an efficient strategy to restore pyrethroid-contaminated soil.


Assuntos
Inseticidas , Praguicidas , Piretrinas , Poluentes do Solo , Aspergillus , Biodegradação Ambiental , Solo
6.
Int. microbiol ; 22(1): 29-39, mar. 2019. ilus, graf, tab
Artigo em Inglês | IBECS | ID: ibc-184811

RESUMO

In a natural ecosystem, various organisms digest and hydrolyze lignocellulose biomass efficiently. Termites are one of them. They digest lignocellulose biomass with the help of symbiotic microorganisms in their gut. Therefore, termites gut may harbor potential sources of microorganisms capable to degrade lignocellulose biomass. In this study, termite gut microbiomes of Cryptotermes brevis species were isolated and identified for their capability to degrade lignin and polysaccharides. Alkali lignin, carboxymethylcellulose, and xylan were used as the only carbon sources in the medium to isolate lignin-, cellulose-, and hemicellulose-degrading bacteria. By this method, two bacteria strains, Bacillus sp. BMP01 and Ochrobactrum oryzae BMP03 strain were isolated and identified. Bacillus sp. BMP01 strain has capabilities to hydrolyze carboxymethylcellulose and xylan to glucose and xylose, respectively. This strain showed high xylanase activity (about 0.21 U/ml) and carboxymethyl cellulase activity (about 0.25 U/ml). The ability to hydrolyze both carboxymethylcellulose and xylan makes it superior to other known cellulolytic bacteria. Ochrobactrum oryzae BMP03 strain showed laccase activity, which indicates its ability to depolymerize lignin. Lignocellulose-degrading bacteria play a vital role in the biological conversion of lignocellulose biomass to biofuel. Overall, this study shows that termite's gut microbiomes are potential sources of lignocellulose-degrading bacteria that can be cultured and used in the biological conversion of lignocellulose biomass to biofuel


No disponible


Assuntos
Animais , Bacillus/isolamento & purificação , Celulose/metabolismo , Intestinos/microbiologia , Isópteros/microbiologia , Lignina/metabolismo , Ochrobactrum/isolamento & purificação , Ochrobactrum/metabolismo , Polissacarídeos/metabolismo , Ração Animal , Bacillus/metabolismo , Glucose/metabolismo , Hidrólise , Madeira , Xilanos/metabolismo , Xilose/metabolismo
7.
Int Microbiol ; 22(1): 29-39, 2019 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-30810928

RESUMO

In a natural ecosystem, various organisms digest and hydrolyze lignocellulose biomass efficiently. Termites are one of them. They digest lignocellulose biomass with the help of symbiotic microorganisms in their gut. Therefore, termites gut may harbor potential sources of microorganisms capable to degrade lignocellulose biomass. In this study, termite gut microbiomes of Cryptotermes brevis species were isolated and identified for their capability to degrade lignin and polysaccharides. Alkali lignin, carboxymethylcellulose, and xylan were used as the only carbon sources in the medium to isolate lignin-, cellulose-, and hemicellulose-degrading bacteria. By this method, two bacteria strains, Bacillus sp. BMP01 and Ochrobactrum oryzae BMP03 strain were isolated and identified. Bacillus sp. BMP01 strain has capabilities to hydrolyze carboxymethylcellulose and xylan to glucose and xylose, respectively. This strain showed high xylanase activity (about 0.21 U/ml) and carboxymethyl cellulase activity (about 0.25 U/ml). The ability to hydrolyze both carboxymethylcellulose and xylan makes it superior to other known cellulolytic bacteria. Ochrobactrum oryzae BMP03 strain showed laccase activity, which indicates its ability to depolymerize lignin. Lignocellulose-degrading bacteria play a vital role in the biological conversion of lignocellulose biomass to biofuel. Overall, this study shows that termite's gut microbiomes are potential sources of lignocellulose-degrading bacteria that can be cultured and used in the biological conversion of lignocellulose biomass to biofuel.


Assuntos
Bacillus/isolamento & purificação , Celulose/metabolismo , Intestinos/microbiologia , Isópteros/microbiologia , Lignina/metabolismo , Ochrobactrum/isolamento & purificação , Polissacarídeos/metabolismo , Ração Animal , Animais , Bacillus/metabolismo , Glucose/metabolismo , Hidrólise , Ochrobactrum/metabolismo , Madeira , Xilanos/metabolismo , Xilose/metabolismo
8.
Ecotoxicol Environ Saf ; 169: 590-599, 2019 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-30476821

RESUMO

In this study, a mixture of carbamates (CRBs) degrading Carb.1b strain was isolated from soil. Based on the morphology and 18S rRNA sequence analysis, the strain was identified as an Ascochyta sp. CBS 237.37 with accession number MG786925. The isolate was employed in two growth mediums (added carbon and carbon-free) enriched with varied concentrations of CRBs ranging from 25 to 85 mg L-1 to assess its degradation efficacy. As determined by the Response Surface Methodology (RSM), optimum parameters for the degradation were: pH value of 7.5 and temperature of 28 °C. The degradation was inhibited at higher concentrations and was found to be 91.2%/94.8%, 67.25%/71.75%, 55.81%/59.81%, 46.85%/49.57% and 36%/40.80% (in carbon-free/added carbon) after 20 d. The removal of the higher concentration CRBs was comparatively slower, and the obtained degradation rate constant (Kavg) 0.03412 d-1. Added carbon and carbon-free medium removed over 86.7%/90.15% of CRBs (85 mgL-1) with the half-life (t1/2) of 26 d and R2 ranging from 0.982 to 0.999; indicating the high tolerance of carb.1b strain towards CRBs. Residual analysis of CRBs biodegradation was performed using GC/MS analysis. This is the first report of degradation of a mixture of CRBs by Ascochyta sp. CBS 237.37. The results of this study can possibly impact the development strategies of bioremediation for the elimination of CRBs.


Assuntos
Ascomicetos/isolamento & purificação , Carbamatos/análise , Microbiologia do Solo , Poluentes do Solo/análise , Ascomicetos/metabolismo , Biodegradação Ambiental , Carbamatos/metabolismo , Cinética , Filogenia , Solo/química , Poluentes do Solo/metabolismo , Temperatura
9.
Environ Technol ; 40(9): 1203-1211, 2019 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-29251554

RESUMO

The combination of NaOH pretreatment and microorganisms isolated from termite was used for releasing wrapped polysaccharides from wheat straw biomass matrix. Different concentrations of NaOH (1%, 3%, 5%, 7% and 10%) were considered to remove lignin and to release polysaccharides as a pretreatment method at 80°C for 4 h before subjecting it to microbial hydrolysis. Data obtained from compositional analysis of pretreated wheat straws show that a significant amount of cellulose and lignin were released after NaOH pretreatments. The amount of cellulose and lignin released was increased with increasing concentration of NaOH in the pretreatment solution. Further analysis of X-Ray diffraction, field emission scanning electron microscope and Fourier transform infrared spectroscopy confirms the removal of lignin and release of cellulose. About 69.5% of lignin was solubilized and 72.67% of cellulose was released after 10% NaOH pretreatment which was the maximum. Data from spectrophotometric analysis of reducing sugar by the 3,5-dinitrosalycilic acid method show that 83.68% (0.706 g/100 ml) of polysaccharides were converted to glucose and xylose by isolated bacteria after the 15th day of hydrolysis.


Assuntos
Álcalis , Triticum , Biomassa , Celulose , Hidrólise , Lignina
10.
Saudi J Biol Sci ; 25(7): 1454-1467, 2018 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-30505195

RESUMO

Biosorption is an effective treatment method for the removal of phenol and cyanide from aqueous solution by saw dust activated carbon (SDAC). Batch experiments were achieved as a function of several experimental parameters, i.e. influence of biosorbent dose (5-60 g/L) contact time (2-40 h), pH (4-12), initial phenol concentration (100-1000 mg/L) and initial cyanide concentration (10-100 mg/L) and temperature (20-40 °C). The biosorption capacities of the biosorbent were detected as 178.85 mg/g for phenol with 300 mg/L of initial concentration and 0.82 mg/g for cyanide with 30 mg/L of initial concentration. The optimum pH is found to be 8 for phenol and 9 for cyanide biosorption. The mono component biosorption equilibrium data for both phenol and cyanide were well defined by Redlich-Peterson model and binary component adsorption equilibrium data well fitted by extended Freundlich model. The percentage removal of phenol and cyanide using SDAC was 66.67% and 73.33%, respectively. Equilibrium established within 30 h for phenol and 28 h for cyanide. Kinetic studies revealed that biosorption of phenol followed pseudo second order indicating adsorption through chemisorption and cyanide followed pseudo first order kinetic model indicating adsorption through physisorption. Thermodynamic studies parameters, i.e., enthalpy (Δh 0), entropy (ΔS 0) and Gibb's free energy (ΔG 0) have also been considered for the system. Thermodynamic modeling studies revealed that the process of cyanide biosorption was endothermic and phenol biosorption was exothermic in nature.

11.
3 Biotech ; 8(10): 447, 2018 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-30333949

RESUMO

In this study, two bacterial strains capable of degrading lignin, cellulose, and hemicellulose were isolated from wood feeding termite. The isolates were identified by 16S rRNA gene sequencing. A bacterium Ochrobactrum oryzae BMP03 capable of degrading lignin was isolated on alkali lignin medium and Bacillus sp. BMP01 strain capable of degrading cellulose and hemicellulose were isolated on carboxymethyl cellulose and xylan media. The efficiency of bacterial degradation was studied by evaluating the composition of rice straw both before and after degradation. The appearance of new cellulose bands at 1382, 1276, 1200, and 871 cm-1, and the absence of former lignin bands at 1726, 1307, and 1246 cm-1 was observed after biodelignification. This was further confirmed by the formation of channeling and layering of the microstructure of biodelignified rice straw observed under electron microscope. Maximum lignin removal was achieved in separate biodelignification and hydrolysis process after the 14th day of treatment by Ochrobactrum oryzae BMP03 (53.74% lignin removal). Hydrolysis of the biodelignified rice straw released 69.96% of total reducing sugars after the 14th day hydrolysis by Bacillus sp. BMP01. In simultaneous delignification and hydrolysis process, about 58.67% of total reducing sugars were obtained after the 13th day of biotreatment. Separate delignification and hydrolysis process were found to be effective in lignin removal and sugar released than the simultaneous process. The bacteria, Bacillus sp. BMP01, has the ability to degrade hemicellulose and cellulose simultaneously. Overall, these results demonstrate that the possibility of rice straw bioconversion into reducing sugars by bacteria from termite gut.

12.
Environ Sci Pollut Res Int ; 25(30): 30585-30596, 2018 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-30173388

RESUMO

Pretreatment is a vital step to enhance the yield of total reducing sugars and biofuel production from lignocellulose biomass. An effective new lignin-degrading and polysaccharide-hydrolyzing bacteria, Ochrobactrum oryzae BMP03 and Bacillus sp. BMP01 strains, were isolated and identified from wood-feeding termite's guts. Wheat straw was biodelignified by Ochrobactrum oryzae BMP03 bacteria strains to degrade lignin and to release the trapped cellulose and hemicellulose. The biodelignified wheat straw was hydrolyzed by Bacillus sp. BMP01 strains. Ochrobactrum oryzae BMP03-Bacillus sp. BMP01 consortia were also performed to analyze the effect of the simultaneous system. It was shown that the production of total reducing sugars in a separate hydrolysis system by Bacillus sp. BMP01 strain achieved 439 mg/g at 16 days of hydrolysis time, which is 9.45% higher than the simultaneous system. About 44.47% lignin was degraded by the Ochrobactrum oryzae BMP03 strain after 16 days of biotreatment. This also contributed for increment in cellulose content by 22.38% and hemicellulose content by 18.64%. The simultaneous system converted 368 mg of reducing sugars/g of wheat straw. Separate biodelignification and hydrolysis have an advantage over the simultaneous system in terms of hydrolysis efficiency and vice versa in terms of biotreatment time. Scanning electron microscope, mid-infrared analysis by Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction analysis confirmed the change in composition due to biotreatment. The biotreatment improved hydrolysis efficiency, which reduces the cost of biofuel production and increases the yield of biofuel. These results indicate the possibilities of biofuel production from wheat straw by employing Ochrobactrum oryzae BMP03 and Bacillus sp. BMP01 bacteria strains.


Assuntos
Bacillus/metabolismo , Biocombustíveis/análise , Ochrobactrum/metabolismo , Açúcares/metabolismo , Triticum/microbiologia , Biodegradação Ambiental , Biomassa , Celulose/metabolismo , Hidrólise , Lignina/metabolismo , Caules de Planta/metabolismo , Caules de Planta/microbiologia , Polissacarídeos/metabolismo , Espectroscopia de Infravermelho com Transformada de Fourier , Açúcares/análise , Triticum/metabolismo
13.
Chemosphere ; 184: 1141-1149, 2017 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-28672695

RESUMO

Capacitive deionization is promising less energy based desalination technique to achieve pure water. In the present study microporous activated carbon was prepared from tea waste biomass by chemical and thermal modification. Further TWBAC was used for preparation of the electrode. The TWBAC electrode was applied in the self-made CDI set up for simultaneous removal of hexavalent chromium [Cr(VI)] and fluoride (F) form mixed feed solution of Cr(VI) and F. The performance of TWBAC electrode was found effective for simultaneous removal of Cr(VI) and F from mixed feed solution. The maximum electrosorption capacity of Cr(VI) and F were found 0.77 and 0.74 mg g-1 for 10 mg L-1 and 2.83 and 2.49 mg g-1 for 100 mg L-1 mixed feed solution respectively. The higher removal of Cr(VI) was found due to the electrosorption selectivity of the divalent CrO42- is higher than that of the monovalent F-. Multicomponent isotherm modeling and kinetic study were carried out in this study. TWBAC CDI electrode could be useful for treatment of a low concentrated Cr(VI) and F containing wastewater.


Assuntos
Cromo/química , Fluoretos/química , Eliminação de Resíduos Líquidos/métodos , Poluentes Químicos da Água/química , Purificação da Água/métodos , Adsorção , Biomassa , Carvão Vegetal , Cromo/análise , Eletrodos , Fluoretos/análise , Cinética , Fosfatos , Chá , Águas Residuárias , Água , Poluentes Químicos da Água/análise
14.
J Environ Biol ; 37(4): 551-6, 2016 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-27498500

RESUMO

The present study aimed to investigate the removal efficiency of cyanide from contaminated water by adsorption, biodegradation and simultaneous adsorption and biodegradation (SAB) process individually in a batch reactor. Adsorption was achieved by using almond shell granules and biodegradation was conducted with suspended cultures of Bacillus cereus, whereas SAB process was carried out using Bacillus cereus and almond shell in a batch reactor. The effect of agitation time, pH, and initial cyanide concentration on the % removal of cyanide has been discussed. Under experimental conditions, optimum removal was obtained at pH 7 with agitation time of 48 hrs and temperature of 35 degrees C. Cyanide was utilized by bacteria as sole source of nitrogen for growth. The removal efficiencies of cyanide by adsorption, biodegradation, and SAB were found to be 91.38%, 95.87%, and 99.63%, respectively, at initial cyanide concentration of 100 mg l(-1). The removal efficiency of SAB was found to be better as compared to that of biodegradation and adsorption alone.


Assuntos
Bacillus cereus/metabolismo , Cianetos/metabolismo , Prunus dulcis/química , Eliminação de Resíduos Líquidos/métodos , Poluentes Químicos da Água/metabolismo , Adsorção , Biodegradação Ambiental , Nozes/química
15.
Sci Rep ; 6: 20893, 2016 Feb 12.
Artigo em Inglês | MEDLINE | ID: mdl-26869357

RESUMO

Natural gas hydrates (NGHs) are solid non-stoichiometric compounds often regarded as a next generation energy source. Successful commercialization of NGH is curtailed by lack of efficient and safe technology for generation, dissociation, storage and transportation. The present work studied the influence of environment compatible biosurfactant on gas hydrate formation. Biosurfactant was produced by Pseudomonas aeruginosa strain A11 and was characterized as rhamnolipids. Purified rhamnolipids reduced the surface tension of water from 72 mN/m to 36 mN/m with Critical Micelle Concentration (CMC) of 70 mg/l. Use of 1000 ppm rhamnolipids solution in C type silica gel bed system increased methane hydrate formation rate by 42.97% and reduced the induction time of hydrate formation by 22.63% as compared to water saturated C type silica gel. Presence of rhamnolipids also shifted methane hydrate formation temperature to higher values relative to the system without biosurfactant. Results from thermodynamic and kinetic studies suggest that rhamnolipids can be applied as environment friendly methane hydrate promoter.

16.
Bioresour Technol ; 142: 9-17, 2013 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-23732917

RESUMO

In the present work, a laboratory scale corn-cob based biofilter inoculated with Bacillus sphaericus (MTCC 8103) was used for degradation of BTEX for a period of 86 days. The overall performance of a biofilter evaluated in terms of its elimination capacity by using 3-D mesh technique. Maximum removal efficiency was found more than 96.43% for all four compounds in each phase of experiments. A maximum elimination capacity (EC) of 60.89 gm(-3)h(-1) of the biofilter was obtained at inlet BTEX load of 63.14 gm(-3)h(-1). The follow-up of carbon dioxide concentration profile through the biofilter revealed that the mass ratio of carbon dioxide produced to the BTEX removed was approximately 2.2, which confirms complete degradation of BTEX. Moreover, BTEX concentration profile along the biofilter depth bed also determined by convection-diffusion reactor (CDR) model.


Assuntos
Benzeno/isolamento & purificação , Filtração/instrumentação , Modelos Teóricos , Tolueno/isolamento & purificação , Xilenos/isolamento & purificação
17.
Bioresour Technol ; 133: 166-74, 2013 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-23425585

RESUMO

Biofiltration of BTEX with corn-cob packing material have been performed for a period of 68 days in five distinct phases. The overall performance of a biofilter has been evaluated in terms of its elimination capacity by using 3-D mesh techniques. Maximum removal efficiency was found more than 99.85% of all four compounds at an EBRT of 3.06 min in phase I for an inlet BTEX concentration of 0.0970, 0.0978, 0.0971 and 0.0968 g m(-3), respectively. Nearly 100% removal achieved at average BTEX loadings of 20.257 g m(-3) h(-1) to biofilter. A maximum elimination capacity (EC) of 20.239 g m(-3) h(-1) of the biofilter was obtained at inlet BTEX load of 20.391 g m(-3) h(-1). Moreover, using convection-diffusion reaction (CDR) model for biofilter depth shows good agreement with the experimental values for benzene, toluene and ethyl benzene, but for o-xylene the model results deviated from the experimental.


Assuntos
Poluentes Atmosféricos/isolamento & purificação , Derivados de Benzeno/isolamento & purificação , Benzeno/isolamento & purificação , Filtração/instrumentação , Tolueno/isolamento & purificação , Xilenos/isolamento & purificação , Zea mays/química , Biodegradação Ambiental , Dióxido de Carbono/química , Filtração/normas , Cinética , Modelos Teóricos , Temperatura , Fatores de Tempo
18.
J Hazard Mater ; 176(1-3): 1-13, 2010 Apr 15.
Artigo em Inglês | MEDLINE | ID: mdl-20004515

RESUMO

Cyanides are fast-acting poisons, can be lethal if exposed in excess. In spite of fact, cyanides are discharged as effluents in large scale from industries every year. Certain bacteria, fungi, algae and plants produce cyanides. It has been observed that microbes and plant systems can degrade cyanides to less toxic compounds. There are many enzymes, which are produced by microorganisms that utilize cyanides as substrate to make alanine, glutamic acid, alfa-amino-butyric acid, beta-cyanoalanine, etc. Present paper deals with different enzymes, their mechanisms and corresponding pathways with respect to the known biochemistry of enzyme and feasibility for the use in treatment of cyanides containing industrial effluents.


Assuntos
Biodegradação Ambiental , Cianetos/metabolismo , Resíduos Industriais/prevenção & controle
19.
J Hazard Mater ; 163(1): 1-11, 2009 Apr 15.
Artigo em Inglês | MEDLINE | ID: mdl-18657360

RESUMO

Cyanides are produced by certain bacteria, fungi, and algae, and may be found in plants and some foods, such as lima beans and almonds. Although cyanides are present in small concentrations in these plants and microorganisms, their large-scale presence in the environment is attributed to the human activities as cyanide compounds are extensively used in industries. Bulk of cyanide occurrence in environment is mainly due to metal finishing and mining industries. Although cyanide can be removed and recovered by several processes, it is still widely discussed and examined due to its potential toxicity and environmental impact. From an economic standpoint, the biological treatment method is cost-effective as compared to chemical and physical methods for cyanide removal. Several microbial species can effectively degrade cyanide into less toxic products. During metabolism, they use cyanide as a nitrogen and carbon source converting it to ammonia and carbonate, if appropriate conditions are maintained. Biological treatment of cyanide under anaerobic as well as aerobic conditions is possible. The present review describes the mechanism and advances in the use of biological treatment for the removal of cyanide compounds and its advantages over other treatment processes. It also includes various microbial pathways for their removal.


Assuntos
Cianetos/isolamento & purificação , Cianetos/metabolismo , Resíduos Industriais , Eliminação de Resíduos Líquidos/métodos , Poluentes Químicos da Água/isolamento & purificação , Poluentes Químicos da Água/metabolismo , Biodegradação Ambiental
20.
J Hazard Mater ; 152(1): 387-96, 2008 Mar 21.
Artigo em Inglês | MEDLINE | ID: mdl-17706348

RESUMO

This paper presents process review and comparative study of biodegradation and adsorption alone with simultaneous adsorption and biodegradation (SAB) process using Pseudomonas fluorescens. Ferrocyanide solution was used for all studies with initial CN(-) concentrations of 50, 100, 200 and 300mg/L, and initial pH of 6. Pseudomonas fluorescens used ferrocyanide as sole source of nitrogen and biodegradation efficiency was observed as 96.4, 94.1, 86.2 and 69.3%, respectively after 60h of agitation. Whereas in adsorption process with granular activated carbon (GAC) as adsorbent, CN(-) removal efficiency was found to be 85.6, 80.1, 70.2 and 50.2%, respectively. But in SAB process the removal efficiency could be more than 70% for all concentrations only at 36h of agitation and achieved removal efficiency of 99.9% for 50 and 100mgCN(-)/L. It was found that SAB process is more effective than biodegradation and adsorption alone.


Assuntos
Cianetos/metabolismo , Metais/metabolismo , Pseudomonas fluorescens/metabolismo , Poluentes Químicos da Água/metabolismo , Adsorção , Meios de Cultura , Concentração de Íons de Hidrogênio , Microscopia Eletrônica de Varredura , Pseudomonas fluorescens/crescimento & desenvolvimento
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