共查询到20条相似文献,搜索用时 31 毫秒
1.
Giovanna Lovato Roberto A. Bezerra José A. D. Rodrigues Suzana M. Ratusznei Marcelo Zaiat 《Applied biochemistry and biotechnology》2012,166(8):2007-2029
The aim of this work was to investigate the effect of different feeding times (2, 4 and 6 h) and applied volumetric organic
loads (4.5, 6.0 and 7.5 gCOD L−1 day−1) on the performance of an anaerobic sequencing batch biofilm reactor (AnSBBR) treating effluent from biodiesel production.
Polyurethane foam cubes were used as inert support in the reactor, and mixing was accomplished by recirculating the liquid
phase. The effect of feeding time on reactor performance showed to be more pronounced at higher values of applied volumetric
organic loads (AVOLs). Highest organic material removal efficiencies achieved at AVOL of 4.5 gCOD L−1 day−1 were 87 % at 4-h feeding against 84 % at 2-h and 6-h feeding. At AVOL of 6.0 gCOD L−1 day−1, highest organic material removal efficiencies achieved with 4-h and 6-h feeding were 84 %, against 71 % at 2-h feeding.
At AVOL of 7.5 gCOD L−1 day−1, organic material removal efficiency achieved with 4-h feeding was 77 %. Hence, longer feeding times favored minimization
of total volatile acids concentration during the cycle as well as in the effluent, guaranteeing process stability and safety. 相似文献
2.
Effect of Substrate Concentration on Dark Fermentation Hydrogen Production Using an Anaerobic Fluidized Bed Reactor 总被引:1,自引:0,他引:1
The effect of substrate (glucose) concentration on the stability and yield of a continuous fermentative process that produces
hydrogen was studied. Four anaerobic fluidized bed reactors (AFBRs) were operated with a hydraulic retention time (HRT) from
1 to 8 h and an influent glucose concentration from 2 to 25 g L−1. The reactors were inoculated with thermally pre-treated anaerobic sludge and operated at a temperature of 30 °C with an
influent pH around 5.5 and an effluent pH of about 3.5. The AFBRs with a HRT of 2 h and a feed strength of 2, 4, and 10 g L−1 showed satisfactory H2 production performance, but the reactor fed with 25 g L−1 of glucose did not. The highest hydrogen yield value was obtained in the reactor with a glucose concentration of 2 g L−1 when it was operated at a HRT of 2 h. The maximum hydrogen production rate value was achieved in the reactor with a HRT of
1 h and a feed strength of 10 g L−1. The AFBRs operated with glucose concentrations of 2 and 4 g L−1 produced greater amounts of acetic and butyric acids, while AFBRs with higher glucose concentrations produced a greater amount
of solvents. 相似文献
3.
Hossein Amani Mohammad Reza Mehrnia Mohammad Hossein Sarrafzadeh Manouchehr Haghighi Mohammad Reza Soudi 《Applied biochemistry and biotechnology》2010,162(2):510-523
There is a lack of fundamental knowledge about the scale up of biosurfactant production. In order to develop suitable technology
of commercialization, carrying out tests in shake flasks and bioreactors was essential. A reactor with integrated foam collector
was designed for biosurfactant production using Bacillus subtilis isolated from agricultural soil. The yield of biosurfactant on biomass (Y
p/x), biosurfactant on sucrose (Y
p/s), and the volumetric production rate (Y) for shake flask were obtained about 0.45 g g−1, 0.18 g g−1, and 0.03 g l−1 h−1, respectively. The best condition for bioreactor was 300 rpm and 1.5 vvm, giving Y
x/s, Y
p/x, Y
p/s, and Y of 0.42 g g−1, 0.595 g g−1, 0.25 g g−1, and 0.057 g l−1 h−1, respectively. The biosurfactant maximum production, 2.5 g l−1, was reached in 44 h of growth, which was 28% better than the shake flask. The obtained volumetric oxygen transfer coefficient
(K
L
a) values at optimum conditions in the shake flask and the bioreactor were found to be around 0.01 and 0.0117 s−1, respectively. Comparison of K
L
a values at optimum conditions shows that biosurfactant production scaling up from shake flask to bioreactor can be done with
K
L
a as scale up criterion very accurately. Nearly 8% of original oil in place was recovered using this biosurfactant after water
flooding in the sand pack. 相似文献
4.
Hong WK Rairakhwada D Seo PS Park SY Hur BK Kim CH Seo JW 《Applied biochemistry and biotechnology》2011,164(8):1468-1480
In the present study, a novel oleaginous Thraustochytrid containing a high content of docosahexaenoic acid (DHA) was isolated
from a mangrove ecosystem in Malaysia. The strain identified as an Aurantiochytrium sp. by 18S rRNA sequencing and named KRS101 used various carbon and nitrogen sources, indicating metabolic versatility. Optimal
culture conditions, thus maximizing cell growth, and high levels of lipid and DHA production, were attained using glucose
(60 g l−1) as carbon source, corn steep solid (10 g l−1) as nitrogen source, and sea salt (15 g l−1). The highest biomass, lipid, and DHA production of KRS101 upon fed-batch fermentation were 50.2 g l−1 (16.7 g l−1 day−1), 21.8 g l−1 (44% DCW), and 8.8 g l−1 (40% TFA), respectively. Similar values were obtained when a cheap substrate like molasses, rather than glucose, was used
as the carbon source (DCW of 52.44 g l−1, lipid and DHA levels of 20.2 and 8.83 g l−1, respectively), indicating that production of microbial oils containing high levels of DHA can be produced economically when
the novel strain is used. 相似文献
5.
Bezerra RA Rodrigues JA Ratusznei SM Zaiat M Foresti E 《Applied biochemistry and biotechnology》2009,157(2):140-158
The aim of this work was to investigate the effect of different feeding times (2, 4, and 6 h) and organic loading rates (3,
6 and 12 gCOD l−1 day−1) on the performance of an anaerobic sequencing batch reactor containing immobilized biomass, as well as to verify the minimum
amount of alkalinity that can be added to the influent. The reactor, in which mixing was achieved by recirculation of the
liquid phase, was maintained at 30 ± 1°C, possessed 2.5 l reactional volume and treated 1.5 l cheese whey in 8-h cycles. Results
showed that the effect of feeding time on reactor performance was more pronounced at higher values of organic loading rates
(OLR). During operation at an OLR of 3 gCOD l−1 day−1, change in feeding time did not affect efficiency of organic matter removal from the reactor. At an OLR of 6 gCOD l−1 day−1, reactor efficiency improved in relation to the lower loading rate and tended to drop at longer feeding times. At an OLR
of 12 gCOD l−1 day−1 the reactor showed to depend more on feeding time; higher feeding times resulted in a decrease in reactor efficiency. Under
all conditions shock loads of 24 gCOD l−1 day−1 caused an increase in acids concentration in the effluent. However, despite this increase, the reactor regained stability
readily and alkalinity supplied to the influent showed to be sufficient to maintain pH close to neutral during operation.
Regardless of applied OLR, operation with feeding time of 2 h was which provided improved stability and rendered the process
less susceptible to shock loads. 相似文献
6.
On the basis of flow injection analysis technology, a simple, accurate, and sensitive method has been developed for the determination
of volatile phenols in environmental water samples by using CdTe/ZnSe nanocrystals as a fluorescent probe. The influences
of coexisting metal ions and volatile phenol substitutes were also investigated. The method developed for analysis of volatile
phenols displayed very good linearity in the range from 1.0 × 10−8 to 4.0 × 10−7 g L−1, with a correlation coefficient greater than 0.995 and a detection limit down to 2.7 × 10−9 g L−1 (signal-to-noise ratio 3). The proposed method was successfully applied to determine the content of volatile phenols in environmental
water samples, and the quantitative recoveries were 93.4–106.1%. A possible reaction mechanism for the quenching of fluorescence
is discussed using UV–vis absorption spectra, fluorescence spectra, and time-resolved luminescence spectra of volatile phenols
obtained by titrating a CdTe/ZnSe nanocrystal aqueous solution and zeta potential data. 相似文献
7.
Rodrigues TH Rocha MV de Macedo GR Gonçalves LR 《Applied biochemistry and biotechnology》2011,164(6):929-943
In this work, the potential of microwave-assisted alkali pretreatment in order to improve the rupture of the recalcitrant
structures of the cashew able bagasse (CAB), lignocellulosic by-product in Brazil with no commercial value, is obtained from
cashew apple process to juice production, was studied. First, biomass composition of CAB was determined, and the percentage
of glucan and lignin was 20.54 ± 0.70% and 33.80 ± 1.30%, respectively. CAB content in terms of cellulose, hemicelluloses,
and lignin, 19.21 ± 0.35%, 12.05 ± 0.37%, and 38.11 ± 0.08%, respectively, was also determined. Results showed that, after
enzymatic hydrolysis, alkali concentration exerted influence on glucose formation, after pretreatment with 0.2 and 1.0 mo L−1 of NaOH (372 ± 12 and 355 ± 37 mg gglucan−1) when 2% (w/v) of cashew apple bagasse pretreated by microwave-assisted alkali pretreatment (CAB-M) was used. On the other hand, pretreatment
time (15–30 min) and microwave power (600–900 W) exerted no significant effect on hydrolysis. On enzymatic hydrolysis step,
improvement on solid percentage (16% w/v) and enzyme load (30 FPU gCAB-M−1) increased glucose concentration to 15 g L−1. The fermentation of the hydrolyzate by Saccharomyces cerevesiae resulted in ethanol concentration and productivity of 5.6 g L−1 and 1.41 g L−1 h−1, respectively. 相似文献
8.
M. López-Sánchez M. J. Ayora-Cañada A. Molina-Díaz M. Siam W. Huber G. Quintás S. Armenta B. Lendl 《Analytical and bioanalytical chemistry》2009,394(8):2137-2144
A mid-infrared enzymatic assay for label-free monitoring of the enzymatic reaction of fructose-1,6-bisphosphatase with fructose
1,6-bisphosphate has been proposed. The whole procedure was done in an automated way operating in the stopped flow mode by
incorporating a temperature-controlled flow cell in a sequential injection manifold. Fourier transform infrared difference
spectra were evaluated for kinetic parameters, like the Michaelis–Menten constant (K
M) of the enzyme and V
max of the reaction. The obtained K
M of the reaction was 14 ± 3 g L−1 (41 μM). Furthermore, inhibition by adenosine 5′-monophosphate (AMP) was evaluated, and the K
MApp value was determined to be 12 ± 2 g L−1 (35 μM) for 7.5 and 15 μM AMP, respectively, with V
max decreasing from 0.1 ± 0.03 to 0.05 ± 0.01 g L−1 min−1. Therefore, AMP exerted a non-competitive inhibition. 相似文献
9.
Sonia Herranz Markéta Bocková María Dolores Marazuela Ji?í Homola María Cruz Moreno-Bondi 《Analytical and bioanalytical chemistry》2010,398(6):2625-2634
A surface plasmon resonance (SPR) biosensor for the detection of microcystins (MCs) in drinking water has been developed.
Several assay formats have been evaluated. The selected format is based on a competitive inhibition assay, in which microcystin-LR
(MCLR) has been covalently immobilized onto the surface of an SPR chip functionalized with a self-assembled monolayer. The
influence of several factors affecting sensor performance, such as the nature and concentration of the antibody, the composition
of the carrier buffer, and the blocking and regeneration solutions, has been evaluated. The optimized SPR biosensor provides
an IC50 0.67 ± 0.09 μg L−1, a detection limit of 73 ± 8 ng L−1, and a dynamic range from 0.2 to 2.0 μg L−1 for MCLR. Cross-reactivity to other related MCs, such as microcystin-RR (88%) and microcystin-YR (94%), has also been measured.
The SPR biosensor can perform four simultaneous determinations in 60 min, and each SPR chip can be reused for at least 40
assay–regeneration cycles without significant binding capacity loss. The biosensor has been successfully applied to the direct
analysis of MCLR in drinking water samples, below the provisional guideline value of 1 μg L−1 established by the World Health Organization for drinking water. 相似文献
10.
A novel laccase producing Basidiomycete Peniophora sp. (NFCCI-2131) was isolated from pulp and paper mill effluent. The optimal temperature and initial pH for laccase production
by the isolate in submerged culture were found to be 30 and 4.6° C, respectively. Maltose (20 g l−1) and tryptone (1.0 g l−1) were the most suitable carbon and nitrogen sources for laccase production. Cu2+ (1.0 mM) and veratryl alcohol induced maximum laccase production giving 6.6 and 6.07 U/ml laccase activity, respectively.
Under optimised culture conditions, 7.6 U/ml activity was obtained, which was 2.4 times higher than that was achieved in basal
medium. An evaluation of the delignification efficiency of the crude enzyme in the presence of redox mediators [2,2’-azino-bis(3-ethylbenzthiazoline-6-sulphonic
acid) and (1-hydroxybenzotriazole)] revealed structural changes in lignin and existence of many active centres for both chemical
and biological degradation of lignin following enzymatic treatment. 相似文献
11.
The results of this study indicate that an increase in CO2 percentage to 30% can enhance Scenedesmus sp. growth in autotrophic cultivation to a maximum of 0.85 g/l as compared with 0.6 g/l obtained in the batch with air (after
6 days of cultivation). However, while the CO2 was higher than 30%, it showed a negative impact on cell growth. A mixotrophic cultivation with 3 g/l of glycerol can achieve
0.38 g l−1 day−1 of the maximum biomass productivity compared with that of 0.21 g l−1 day−1 in autotrophic cultivation. Nevertheless, the lutein content of the mixotrophic cultivation was 0.08–0.1% lower than 0.2–0.25%
obtained in autotrophic cultivation, which led to a lower lutein productivity of 0.36 mg l−1 day−1 in the mixotrophic batch compared with 0.44 mg l−1 day−1 obtained in the autotrophic batch. The limitation of cell growth in the mixotrophic cultivation would be the contributing
factor regarding the lower lutein productivity. The mixotrophic cultivation of repeated batch to remove potential inhibitive
metabolic products from glycerol catabolism does not show an obvious improvement on biomass. Conclusively, mixotrophic cultivation
achieves higher biomass productivity with lower lutein content than that of autotrophic cultivation, which leads to lower
lutein productivity. Therefore, the autotrophic cultivation is preferred in the lutein production. 相似文献
12.
Natalia García-Otero Carmen Teijeiro-Valiño Jacobo Otero-Romaní Elena Peña-Vázquez Antonio Moreda-Piñeiro Pilar Bermejo-Barrera 《Analytical and bioanalytical chemistry》2009,395(4):1107-1115
Nickel(II) and lead(II) ionic imprinted 8-hydroxyquinoline polymers were synthesized by a precipitation polymerization technique
and were used as selective solid phase extraction supports for the determination of nickel and lead in seawater by flow injection
solid phase extraction on-line inductively coupled plasma-optical emission spectrometry. An optimum loading flow rate of 2.25 mL min−1 for 2 min and an elution flow rate of 2.25 mL min−1 for 1 min gave an enrichment factor of 15 for nickel. However, a low dynamic capacity and/or rate for adsorption and desorption
was found for lead ionic imprinted polymer and a flow rate of 3.00 mL min−1 for 4-min loading and a flow rate of 2.25 mL min−1 for 1-min elution gave a enrichment factor of 5. The limit of detection was 0.33 μg L−1 for nickel and 1.88 μg L−1 for lead, with a precision (n = 11) of 8% (2.37 μg Ni L−1) for nickel and 11% (8.38 μg Pb L−1) for lead. Accuracy was also assessed by analyzing SLEW-3 (estuarine water) and TM-24 (lake water) certified reference materials,
and the values determined were in good agreement with the certified concentrations. 相似文献
13.
An anodic stripping voltammetric procedure for the determination of Cu(II) at an in situ-plated stannum film electrode (SnFE)
was described. The results indicated that the SnFE had an attractive electroanalytical performance, with two distinct voltammetric
stripping signals for copper and stannum, and showed the superior advantage for the determination of copper compared with
the bismuth film electrode. Several experimental parameters were optimized. The SnFE exhibited highly linear behavior in the
concentration range from 1.0 to 100.0 μg L−1 of Cu(II) (r = 0.994) with the detection limit of 0.61 μg L−1 (S/N = 3), and the relative standard deviation for a solution containing 40.0 μg L−1 Cu(II) was 2.2% (n = 8). The procedure has been successfully applied for the determination of Cu(II) in lake water sample. 相似文献
14.
Jun Yao Hong Xu Ningning Shi Xin Cao Xiaohai Feng Sha Li Pingkai Ouyang 《Applied biochemistry and biotechnology》2010,160(8):2332-2341
Bacillus subtilis NX-2 produces γ-polyglutamic acid (γ-PGA) when using glucose and l-glutamate as carbon sources. The conversion of carbon sources into γ-PGA was analyzed with the 13C-NMR method after enriching the media with 13C-labeled glucose. The results showed that the percentage of γ-PGA monomers derived from glucose was relatively low, approximately
6% and 9%, respectively, with an initial glucose concentration of 30 and 40 g L−1. It was concluded that glucose was utilized mainly as the growth-limiting substrate for cell growth and supplied the required
energy during γ-PGA biosynthesis, while l-glutamate was preferred as the main substrate for γ-PGA formation. To achieve an efficient conversion of l-glutamate and enhance the γ-PGA production, a fed-batch culture was proposed by feeding of glucose. By this method, supplied
l-glutamate (40 g L−1) was completely depleted, and γ-PGA yield was attained 42 g L−1. 相似文献
15.
The precipitation polymerizations of N-tert-butylacrylamide (NtBAM) in water are demonstrated; for example, the polymerization with potassium peroxodisulfate using a 15 g L−1 (118 mmol L−1) concentration of NtBAM in the feed ([NtBAM]0) was performed at 70 °C for 12 h, quantitatively producing poly(N-tert-butylacrylamide) particles with a number-average diameter (d
n) of 203 nm and a coefficient of variation (C
v) of 4.7%. The particle sizes were controlled in the d
ns range between 75 and 494 nm by changing the monomer feeds or adding an electrolyte such as NaCl. The solid contents in the
resulting aqueous latex solutions ranged from 0.1 to 1.5%, whereas it increased to 4.8% by applying a “shot-growth” technique.
The polymerization in water under a somewhat unique condition is described, which was started from a heterogeneous system
due to the presence of significantly large amounts of monomers ([NtBAM]0 = 50 g L−1). This also provided monodisperse latexes with the d
n of 370 nm in 96% yield, in which the solid content reached 4.9%. 相似文献
16.
A compact miniaturized continuous flow system for the determination of urea content in milk 总被引:1,自引:0,他引:1
Willian Toito Suarez Osmundo Dantas Pessoa-Neto Vagner Bezerra dos Santos Ana Rita de Araujo Nogueira Ronaldo Censi Faria Orlando Fatibello-Filho Mar Puyol Julián Alonso 《Analytical and bioanalytical chemistry》2010,398(3):1525-1533
A multicommutation-based flow system with photometric detection was developed, employing an analytical microsystem constructed
with low temperature co-fired ceramics (LTCC) technology, a solid-phase reactor containing particles of Canavalia ensiformis DC (urease source) immobilized with glutaraldehyde, and a mini-photometer coupled directly to the microsystem which monolithically
integrates a continuous flow cell. The determination of urea in milk was based on the hydrolysis of urea in the solid-phase
reactor and the ammonium ions produced were monitored using the Berthelot reaction. The analytical curve was linear in the
urea concentration range from 1.0 × 10−4 to 5.0 × 10−3 mol L−1 with a limit of detection of 8.0 × 10−6 mol L−1. The relative standard deviation (RSD) for a 2.0 × 10−3 mol L−1 urea solution was lower than 0.4% (n = 10) and the sample throughput was 13 h−1. To check the reproducibility of the flow system, calibration curves were obtained with freshly prepared solutions on different
days and the RSD obtained was 4.7% (n = 6). Accuracy was assessed by comparing the results of the proposed method with those from the official procedure and the
data are in close agreement, at a 95% confidence level. 相似文献
17.
Xiaolin Pei Qiuyan Wang Xiaofeng Qiu Longbin Ying Junhua Tao Tian Xie 《Applied biochemistry and biotechnology》2010,162(5):1423-1434
2-Deoxyribose-5-phosphate aldolase (DERA) catalyzes a sequential aldol reaction useful in synthetic chemistry. In this work,
the effect of a feeding strategy on the production of a thermophilic DERA was investigated in fed-batch cultures of recombinant
Escherichia coli BL21 (pET303-DERA008). The predetermined specific growth rate (μ
set) was evaluated at 0.20, 0.15, and 0.10 h−1, respectively. The DERA concentration and volumetric productivity were associated with μ
set. The cells synthesized the enzyme most efficiently at μ
set = 0.15 h−1. The maximum enzyme concentration (5.12 g/L) and total volumetric productivity (0.256 g L−1 h−1) obtained were over 10 and five times higher than that from traditional batch cultures. Furthermore, the acetate concentration
remained at a relatively low level, less than 0.4 g/L, under this condition which would not inhibit cell growth and target
protein expression. Thus, a specific growth rate control strategy has been successfully applied to induce fed-batch cultures
for the maximal production of the thermophilic 2-deoxyribose-5-phosphate aldolase. 相似文献
18.
T. Kakavand M. Sadeghi L. Mokhtari A. Majdabadi 《Journal of Radioanalytical and Nuclear Chemistry》2010,283(1):197-201
The electroplating of zinc is carried out in an alkaline cyanide bath. Operating parameters such as pH, temperature, and current
density and amount of the electrolyte components are optimized. The optimum conditions of the electrodeposition of zinc were
as follows: 2.7 g L−1 ZnO, 7.1 g L−1 KCN, 11.1 g L−1 KOH, pH = 13–14, DC current density of ca 8.55 mA cm−2 at 40–50 °C temperature with 89% current efficiency. SEM photomicrographs revealed fine-grained structure of the deposit
from the bath. 相似文献
19.
Eduardo Marafon Lauro T. Kubota Yoshitaka Gushikem 《Journal of Solid State Electrochemistry》2009,13(3):377-383
SiO2/ZrO2/C carbon ceramic material with composition (in wt%) SiO2 = 50, ZrO2 = 20, and C = 30 was prepared by the sol–gel-processing method. A high-resolution transmission electron microscopy image
showed that ZrO2 and the graphite particles are well dispersed inside the matrix. The electrical conductivity obtained for the pressed disks
of the material was 18 S cm−1, indicating that C particles are also well interconnected inside the solid. An electrode modified with flavin adenine dinucleotide
(FAD) prepared by immersing the solid SiO2/ZrO2/C, molded as a pressed disk, inside a FAD solution (1.0 × 10−3 mol L−1) was used to investigate the electrocatalytic reduction of bromate and iodate. The reduction of both ions occurred at a peak
potential of −0.41 V vs. the saturated calomel reference electrode. The linear response range (lrr) and detection limit (dl)
were: BrO3
−, lrr = 4.98 × 10−5–1.23 × 10−3 mol L−1 and dl = 2.33 μmol L−1; IO3
−, lrr = 4.98 × 10−5 up to 2.42 × 10−3 and dl = 1.46 μmol L−1 for iodate. 相似文献
20.
A flow injection system was developed for on-line sorbent extraction preconcentration and flame atomic absorption spectrometric
determination of cadmium in natural water samples. The non-charged cadmium complex with diethyl-dithiophosphate (DDPA) was
formed on-line in 0.1 mol L−1 HNO3 and retained on the hydrophobic poly-chlorotrifluoroethylene (PCTFE) sorbent material. The adsorbed complex was eluted with
isobutyl methylketone (IBMK) and injected directly into the nebulizer via a flow compensation unit. All major chemical and
flow parameters affecting the complex formation adsorption and elution as well as interference were studied and optimized.
By processing 2.4 mL of sample, the enhancement factor was 39 and the sampling frequency was 50 h−1. For 30 s preconcentration time the detection limit was 0.3 μg L−1 and the relative standard deviation at 5.0 μg L−1 Cd concentration level was 2.9%. The calibration curve was linear in the range 0.8–40.0 μg L−1. The accuracy of the method was estimated by analyzing a certified reference material NIST-CRM 1643d (Trace elements in water).
Good recoveries were obtained for spiked natural-water and waste-water samples.
Correspondence: Aristidis N. Anthemidis, Laboratory of Analytical Chemistry, Department of Chemistry, Aristotle University,
GR-Thessaloniki 54124, Greece 相似文献