Measurement of H2 consumption and its role in continuous fermentative hydrogen production

2008 ◽  
Vol 57 (5) ◽  
pp. 681-685 ◽  
Author(s):  
J. T. Kraemer ◽  
D. M. Bagley
Keyword(s):  
Continuous Flow ◽  
H2 Production ◽  
Continuous Reactor ◽  
Yield Increase ◽  
Fermentative Hydrogen Production ◽  
Consumption Rates ◽  
Fermentative Hydrogen ◽  
H2 Yield ◽  
First Time

To maximise the yield from fermentative H2 production, H2 consumption must be minimised. This work demonstrated for the first time that H2 consumption exists in an established continuous-flow biohydrogen system. The rate of H2 consumption was found to be related to the concentration of CO2, with H2 consumption inhibited at both low and high CO2. N2 sparging of the continuous reactor at 31 mL/min/L-liquid increased the H2 yield from 1.31 to 1.87 mol H2/mol glucose, but did not significantly change the in-situ rate of H2 consumption (0.07–0.09 mM/h). Assuming sparging completely inhibited H2 consumption, it could only account for 2–11% of the H2 yield increase during sparging, based on H2 consumption rates measured in the reactor and in vials. Therefore, H2 consumption may be of minor concern for continuous biohydrogen systems.

Fermentative Hydrogen Production - Process Design and Bioreactors

2012 ◽  
Vol 33 (4) ◽  
pp. 585-594 ◽  
Author(s):  
Małgorzata Waligórska
Keyword(s):  
Production Rate ◽  
Alternative Energy ◽  
Fossil Fuels ◽  
H2 Production ◽  
Factors Affecting ◽  
Fermentative Hydrogen Production ◽  
Production Factors ◽  
Fermentative Hydrogen ◽  
And Performance ◽  
H2 Yield

Substitution of fossil fuels with alternative energy carriers has become necessary due to climate change and fossil fuel shortages. Fermentation as a way of producing biohydrogen, an attractive and environmentally friendly future energy carrier, has captured received increasing attention in recent years because of its high H2 production rate and a variety of readily available waste substrates used in the process. This paper discusses the state-of-the-art of fermentative biohydrogen production, factors affecting this process, as well as various bioreactor configurations and performance parameters, including H2 yield and H2 production rate.

scholarly journals Biohydrogen Production from Food Waste: Influence of the Inoculum-To-Substrate Ratio

2018 ◽  
Vol 10 (12) ◽  
pp. 4506 ◽  
Author(s):  
Giovanna Cappai ◽  
Giorgia De Gioannis ◽  
Aldo Muntoni ◽  
Daniela Spiga ◽  
Maria Rosaria Boni ◽  
...  
Keyword(s):  
Food Waste ◽  
H2 Production ◽  
Fermentation Products ◽  
Fermentative Hydrogen Production ◽  
Batch Tests ◽  
Optimal Value ◽  
Substrate Ratio ◽  
Fermentative Hydrogen ◽  
H2 Yield ◽  
Maximum Production Rate

In this study, the influence of the inoculum-to-substrate ratio (ISR) on dark fermentative hydrogen production from food waste (FW) was evaluated. ISR values ranging from 0.05 to 0.25 g VSinoculum/g VSsubstrate were investigated by performing batch tests at T = 39 °C and pH = 6.5, the latter being the optimal value identified based on a previous study. The ISR was found to affect the fermentation process, clearly showing that an adequate ISR is essential in order to optimise the process kinetics and the H2 yield. An ISR of 0.14 proved to optimum, leading to a maximum H2 yield of 88.8 L H2/kg VSFW and a maximum production rate of 10.8 L H2/kg VSFW∙h. The analysis of the fermentation products indicated that the observed highest H2 production mostly derived from the typical acetate/butyrate-type fermentation.

scholarly journals Microbial N2O consumption in and above marine N2O production hotspots

2020 ◽  
Author(s):  
Xin Sun ◽  
Amal Jayakumar ◽  
John C. Tracey ◽  
Elizabeth Wallace ◽  
Colette L. Kelly ◽  
...  
Keyword(s):  
Kinetic Parameters ◽  
Substrate Affinity ◽  
N2o Production ◽  
Anoxic Waters ◽  
Production And Consumption ◽  
Consumption Rates ◽  
Anoxic Zones ◽  
First Time ◽  
Microbial N

AbstractThe ocean is a net source of N2O, a potent greenhouse gas and ozone-depleting agent. However, the removal of N2O via microbial N2O consumption is poorly constrained and rate measurements have been restricted to anoxic waters. Here we expand N2O consumption measurements from anoxic zones to the sharp oxygen gradient above them, and experimentally determine kinetic parameters in both oxic and anoxic seawater for the first time. We find that the substrate affinity, O2 tolerance, and community composition of N2O-consuming microbes in oxic waters differ from those in the underlying anoxic layers. Kinetic parameters determined here are used to model in situ N2O production and consumption rates. Estimated in situ rates differ from measured rates, confirming the necessity to consider kinetics when predicting N2O cycling. Microbes from the oxic layer consume N2O under anoxic conditions at a much faster rate than microbes from anoxic zones. These experimental results are in keeping with model results which indicate that N2O consumption likely takes place above the oxygen deficient zone (ODZ). Thus, the dynamic layer with steep O2 and N2O gradients right above the ODZ is a previously ignored potential gatekeeper of N2O and should be accounted for in the marine N2O budget.

scholarly journals Susceptibility of the Formate Hydrogenlyase Reaction to the Protonophore CCCP Depends on the Total Hydrogenase Composition

Inorganics ◽  
2020 ◽  
Vol 8 (6) ◽  
pp. 38
Author(s):  
Janik Telleria Marloth ◽  
Constanze Pinske
Keyword(s):  
Complex I ◽  
H2 Production ◽  
Proton Pumping ◽  
Fermentative Hydrogen Production ◽  
Iron Sulfur ◽  
Formate Hydrogenlyase ◽  
Respiratory Complex I ◽  
Fermentative Hydrogen ◽  
Pumping Activity ◽  
Higher Sensitivity

Fermentative hydrogen production by enterobacteria derives from the activity of the formate hydrogenlyase (FHL) complex, which couples formate oxidation to H2 production. The molybdenum-containing formate dehydrogenase and type-4 [NiFe]-hydrogenase together with three iron-sulfur proteins form the soluble domain, which is attached to the membrane by two integral membrane subunits. The FHL complex is phylogenetically related to respiratory complex I, and it is suspected that it has a role in energy conservation similar to the proton-pumping activity of complex I. We monitored the H2-producing activity of FHL in the presence of different concentrations of the protonophore CCCP. We found an inhibition with an apparent EC50 of 31 µM CCCP in the presence of glucose, a higher tolerance towards CCCP when only the oxidizing hydrogenase Hyd-1 was present, but a higher sensitivity when only Hyd-2 was present. The presence of 200 mM monovalent cations reduced the FHL activity by more than 20%. The Na+/H+ antiporter inhibitor 5-(N-ethyl-N-isopropyl)-amiloride (EIPA) combined with CCCP completely inhibited H2 production. These results indicate a coupling not only between Na+ transport activity and H2 production activity, but also between the FHL reaction, proton import and cation export.

scholarly journals Predictive modeling to determine oxygen and ozone doses applicable to in situ remediation of polluted water bodies

2021 ◽  
Author(s):  
Jacobo Tabla-Hernandez ◽  
Alejandro V. Dellepere ◽  
Ernesto Mangas-Ramírez
Keyword(s):  
Predictive Modeling ◽  
Continuous Flow ◽  
Oxygen Demand ◽  
Fecal Coliforms ◽  
Polluted Water ◽  
In Situ Remediation ◽  
Artificial Lake ◽  
Pollution Levels ◽  
First Time

Abstract This work shows the results for the first time of calibrating and validating a mathematical model, capable of predicting the amounts of O3 and O2 necessary to reduce pollution levels in a lake based on the Chemical Oxygen Demand (COD), Biochemical Oxygen Demand (BOD5), Total nitrogen (TN), Total phosphorus (TP) and Fecal coliforms (FC) concentrations. The model was designed to treat a natural or artificial lake as though it were an aerated lagoon operating as an idealized Continuous flow complete-mix reactor. The O3 yield constant for eliminating the non-biodegradable fraction of COD and for deactivating fecal coliforms were laboratory derived and calibrated with field values. Based on the field parameters, the model accurately predicted a reduction in BOD5, COD, TN, TP and FC of 53 %, 51 %, 39 %, 42 % and 98 %, respectively. The model proved to be effective in predicting O2 and O3 demand and time of recovery of a polluted water body.

Effect of pH, ORP and Influent COD on Hydrogen Content in Fermentative Hydrogen Production

2010 ◽  
Vol 156-157 ◽  
pp. 877-881 ◽  
Author(s):  
Lei Lei Zhu ◽  
Bing Wang ◽  
Shuang Gao ◽  
Xin Yao ◽  
Li Cao ◽  
...  
Keyword(s):  
Hydrogen Production ◽  
Hydrogen Content ◽  
Continuous Flow ◽  
Reduction Potential ◽  
Hydraulic Retention Time ◽  
Tank Reactor ◽  
Fermentative Hydrogen Production ◽  
Oxidation Reduction ◽  
Oxidation Reduction Potential ◽  
Fermentative Hydrogen

Fermentative hydrogen production was carried out using a continuous flow stirred tank reactor (CSTR) for the investigation of the hydrogen content in the biogas. Molasses was used as the substrate; hydraulic retention time (HRT) was 6 h; the temperature was in the range of 35±1 .It was showed that hydrogen content increased from 38% to 59% when pH decreased from 5 to 4.6 with oxidation-reduction potential (ORP) increased from -420 mV to -380 mV. The hydrogen content dropped from 50% to 30% as influent COD was improved from4000 mg/L to 6000 mg/L. Hydrogen content increased to 35% when influent COD was improved to 7000 mg/L, however decreased to 25% when influent COD was 8000 mg/L. Ethanol in terminal products is accompanied with hydrogen production but with lower hydrogen content. Butyric acid indicates higher hydrogen content than ethanol.

scholarly journals Collection of some microbial consortia producing hydrogen from anaerobic wastes

2013 ◽  
Vol 16 (1) ◽  
pp. 51-59
Author(s):  
Hanh Thi Kim Pham ◽  
Anh Thi Ngoc To ◽  
Anh Duong Tam Nguyen
Keyword(s):  
Room Temperature ◽  
Waste Treatment ◽  
Treatment Plant ◽  
H2 Production ◽  
Microbial Consortia ◽  
Hydrogen Yield ◽  
Cultivation Time ◽  
Fermentative Hydrogen Production ◽  
Waste Treatment Plant ◽  
Fermentative Hydrogen

The preparation of hydrogen-producing microbial consortia from three anaerobic digested sludges were carried out by four different pretreatment methods (heat – shock, acid, base and aeration treatment) as well as untreatment. The obtained microbial seeds have been estimated for their stability in fermentative hydrogen production by three consecutive batch fermentations under the same conditions of pH 6.5, room temperature and cultivation time and also investigated the H2 fermentation from different concentrations of glucose and xylose. Three microbial seeds have the most effective H2 production at 5 g/l of glucose or xylose after 48 h cultivation time. The sewage sludge pretreated at 80oC for 30 minutes shows the hydrogen yield of 1.27 mol/mol glucose and 0.82 mol/mol xylose. The sludge in the biogas tank pretreated at 60oC for 30 minutes has the hydrogen yield of 1.27 mol/mol glucose and 0.71 mol/mol xylose. The sludge of the Hoa Binh waste treatment plant pretreated at 60oC for 30 minutes presents the hydrogen yield of 1.31 mol/mol glucose and 0.66 mol/mol xylose.

Probing the Dynamic Self-Assembly Behaviour of Photoswitchable Wormlike Micelles in Real Time

2018 ◽  
Author(s):  
Elaine A. Kelly ◽  
Judith E. Houston ◽  
Rachel Evans
Keyword(s):  
Real Time ◽  
Absorption Spectroscopy ◽  
Self Assembly ◽  
Uv Light ◽  
Wormlike Micelles ◽  
Tetraethylene Glycol ◽  
Light Illumination ◽  
First Time ◽  
Dependent Processes

Understanding the dynamic self-assembly behaviour of azobenzene photosurfactants (AzoPS) is crucial to advance their use in controlled release applications such as<i></i>drug delivery and micellar catalysis. Currently, their behaviour in the equilibrium <i>cis-</i>and <i>trans</i>-photostationary states is more widely understood than during the photoisomerisation process itself. Here, we investigate the time-dependent self-assembly of the different photoisomers of a model neutral AzoPS, <a>tetraethylene glycol mono(4′,4-octyloxy,octyl-azobenzene) </a>(C<sub>8</sub>AzoOC<sub>8</sub>E<sub>4</sub>) using small-angle neutron scattering (SANS). We show that the incorporation of <i>in-situ</i>UV-Vis absorption spectroscopy with SANS allows the scattering profile, and hence micelle shape, to be correlated with the extent of photoisomerisation in real-time. It was observed that C<sub>8</sub>AzoOC<sub>8</sub>E<sub>4</sub>could switch between wormlike micelles (<i>trans</i>native state) and fractal aggregates (under UV light), with changes in the self-assembled structure arising concurrently with changes in the absorption spectrum. Wormlike micelles could be recovered within 60 seconds of blue light illumination. To the best of our knowledge, this is the first time the degree of AzoPS photoisomerisation has been tracked <i>in</i><i>-situ</i>through combined UV-Vis absorption spectroscopy-SANS measurements. This technique could be widely used to gain mechanistic and kinetic insights into light-dependent processes that are reliant on self-assembly.

The Total Synthesis of Rhabdastrellic Acid A

2018 ◽  
Author(s):  
Yaroslav Boyko ◽  
Christopher Huck ◽  
David Sarlah
Keyword(s):  
Total Synthesis ◽  
Late Stage ◽  
Cross Coupling ◽  
Side Chains ◽  
General Strategy ◽  
Modular Approach ◽  
Linear Sequence ◽  
Generating Sequence ◽  
First Time

<div>The first total synthesis of rhabdastrellic acid A, a highly cytotoxic isomalabaricane triterpenoid, has been accomplished in a linear sequence of 14 steps from commercial geranylacetone. The prominently strained <i>trans-syn-trans</i>-perhydrobenz[<i>e</i>]indene core characteristic of the isomalabaricanes is efficiently accessed in a selective manner for the first time through a rapid, complexity-generating sequence incorporating a reductive radical polyene cyclization, an unprecedented oxidative Rautenstrauch cycloisomerization, and umpolung 𝛼-substitution of a <i>p</i>-toluenesulfonylhydrazone with in situ reductive transposition. A late-stage cross-coupling in concert with a modular approach to polyunsaturated side chains renders this a general strategy for the synthesis of numerous family members of these synthetically challenging and hitherto inaccessible marine triterpenoids.</div>

Functional response of Fucus vesiculosus communities to tributyltin measured in an in situ continuous flow-through system

Hydrobiologia ◽  
1989 ◽  
Vol 188-189 (1) ◽  
pp. 277-283 ◽  
Author(s):  
C. Lindblad ◽  
U. Kautsky ◽  
C. André ◽  
N. Kautsky ◽  
M. Tedengren
Keyword(s):  
Functional Response ◽  
Continuous Flow ◽  
Fucus Vesiculosus ◽  
Flow Through
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