Apparent hydrogen consumption in acid reactors: observations and implications

2009 ◽  
Vol 59 (7) ◽  
pp. 1441-1447 ◽  
Author(s):  
C. Dinamarca ◽  
R. Bakke
Keyword(s):  
Hydrogen Production ◽  
Biomass Concentration ◽  
H2 Production ◽  
Dark Fermentation ◽  
Operating Conditions ◽  
Fuel Production ◽  
Hydrogen Consumption ◽  
Operation Conditions ◽  
Green Fuel ◽  
High Biomass Concentration

Investigations of hydrogen production by dark fermentation have received increasing attention as a green fuel production process. Research focus is mainly on yields and rates of hydrogen production under different operation conditions. The importance of hydrogen consumption is addressed here, based on results from lab-scale reactors. Experiments were run using mixed cultures and a variety of operating conditions: HRT 6-40 hours; temperature 25–55°C. Initial hydrogen yields between 0.8–1.5 mol H2/mol glucose and ≈50% H2 in headspace was observed, followed by a decrease in hydrogen production as the culture matures, resulting in hydrogen yields down to 0.02 mol H2/mol glucose. It is concluded that hydrogen or “hydrogen equivalents” consumption is significant, especially in reactors with high biomass concentration and/or high sludge age. Sustainable H2 production by dark fermentation alone is therefore not likely to be developed. The results suggest that it is possible to control and avoid significant H2 production in dark fermentation. Minimizing H2 production can be useful in preparation of organic feed for other bio-fuel production processes, such as methanogenic processes and bio-electrochemical H2 production.

scholarly journals Optimization of Biohydrogen Production with Biomechatronics

2014 ◽  
Vol 2014 ◽  
pp. 1-11 ◽  
Author(s):  
Shao-Yi Hsia ◽  
Yu-Tuan Chou
Keyword(s):  
Hydrogen Production ◽  
Taguchi Method ◽  
Alternative Energy ◽  
Production Efficiency ◽  
Biological Effects ◽  
Dark Fermentation ◽  
Operating Conditions ◽  
Biohydrogen Production ◽  
Process Conditions ◽  
Ultrasonic Frequency

Massive utilization of petroleum and natural gas caused fossil fuel shortages. Consequently, a large amount of carbon dioxide and other pollutants are produced and induced environmental impact. Hydrogen is considered a clean and alternative energy source. It contains relatively high amount of energy compared with other fuels and by-product is water. In this study, the combination of ultrasonic mechanical and biological effects is utilized to increase biohydrogen production from dark fermentation bacteria. The hydrogen production is affected by many process conditions. For obtaining the optimal result, experimental design is planned using the Taguchi Method. Four controlling factors, the ultrasonic frequency, energy, exposure time, and starch concentration, are considered to calculate the highest hydrogen production by the Taguchi Method. Under the best operating conditions, the biohydrogen production efficiency of dark fermentation increases by 19.11%. Results have shown that the combination of ultrasound and biological reactors for dark fermentation hydrogen production outperforms the traditional biohydrogen production method. The ultrasonic mechanical effects in this research always own different significances on biohydrogen production.

scholarly journals Preliminary Equipment Design for On-Board Hydrogen Production by Steam Reforming in Palladium Membrane Reactors

2019 ◽  
Vol 3 (1) ◽  
pp. 6 ◽  
Author(s):  
Marina Holgado ◽  
David Alique
Keyword(s):  
Hydrogen Production ◽  
H2 Production ◽  
Single Step ◽  
Operating Conditions ◽  
Membrane Reactors ◽  
Transport Sector ◽  
Main Role ◽  
Pure Hydrogen ◽  
The European Union ◽  
Membrane Area

Hydrogen, as an energy carrier, can take the main role in the transition to a new energy model based on renewable sources. However, its application in the transport sector is limited by its difficult storage and the lack of infrastructure for its distribution. On-board H2 production is proposed as a possible solution to these problems, especially in the case of considering renewable feedstocks such as bio-ethanol or bio-methane. This work addresses a first approach for analyzing the viability of these alternatives by using Pd-membrane reactors in polymer electrolyte membrane fuel cell (PEM-FC) vehicles. It has been demonstrated that the use of Pd-based membrane reactors enhances hydrogen productivity and provides enough pure hydrogen to feed the PEM-FC requirements in one single step. Both alternatives seem to be feasible, although the methane-based on-board hydrogen production offers some additional advantages. For this case, it is possible to generate 1.82 kmol h−1 of pure H2 to feed the PEM-FC while minimizing the CO2 emissions to 71 g CO2/100 km. This value would be under the future emissions limits proposed by the European Union (EU) for year 2020. In this case, the operating conditions of the on-board reformer are T = 650 °C, Pret = 10 bar and H2O/CH4 = 2.25, requiring 1 kg of catalyst load and a membrane area of 1.76 m2.

scholarly journals Bio-Hydrogen Production from Wastewater: A Comparative Study of Low Energy Intensive Production Processes

2021 ◽  
Vol 3 (1) ◽  
pp. 156-182
Author(s):  
A K M Khabirul Islam ◽  
Patrick S. M. Dunlop ◽  
Neil J. Hewitt ◽  
Rose Lenihan ◽  
Caterina Brandoni
Keyword(s):  
Wastewater Treatment ◽  
Hydrogen Production ◽  
Scale Up ◽  
Clean Energy ◽  
H2 Production ◽  
Dark Fermentation ◽  
Low Energy ◽  
Synthetic Wastewater ◽  
Hydrogen Yield ◽  
Wastewater Remediation

Billions of litres of wastewater are produced daily from domestic and industrial areas, and whilst wastewater is often perceived as a problem, it has the potential to be viewed as a rich source for resources and energy. Wastewater contains between four and five times more energy than is required to treat it, and is a potential source of bio-hydrogen—a clean energy vector, a feedstock chemical and a fuel, widely recognised to have a role in the decarbonisation of the future energy system. This paper investigates sustainable, low-energy intensive routes for hydrogen production from wastewater, critically analysing five technologies, namely photo-fermentation, dark fermentation, photocatalysis, microbial photo electrochemical processes and microbial electrolysis cells (MECs). The paper compares key parameters influencing H2 production yield, such as pH, temperature and reactor design, summarises the state of the art in each area, and highlights the scale-up technical challenges. In addition to H2 production, these processes can be used for partial wastewater remediation, providing at least 45% reduction in chemical oxygen demand (COD), and are suitable for integration into existing wastewater treatment plants. Key advancements in lab-based research are included, highlighting the potential for each technology to contribute to the development of clean energy. Whilst there have been efforts to scale dark fermentation, electro and photo chemical technologies are still at the early stages of development (Technology Readiness Levels below 4); therefore, pilot plants and demonstrators sited at wastewater treatment facilities are needed to assess commercial viability. As such, a multidisciplinary approach is needed to overcome the current barriers to implementation, integrating expertise in engineering, chemistry and microbiology with the commercial experience of both water and energy sectors. The review concludes by highlighting MECs as a promising technology, due to excellent system modularity, good hydrogen yield (3.6–7.9 L/L/d from synthetic wastewater) and the potential to remove up to 80% COD from influent streams.

scholarly journals Growth CO2 Consumption, and H2 Production of Anabaena Variabilis ATCC 29413-U Under Different Irradiances and CO2 Concentrations

2006 ◽  
Author(s):  
Halil Berberoglu ◽  
Natasha Barra ◽  
Laurent Pilon ◽  
Jenny Jay
Keyword(s):  
Hydrogen Production ◽  
Gas Phase ◽  
Mole Fraction ◽  
Maximum Growth ◽  
H2 Production ◽  
Anabaena Variabilis ◽  
Operating Conditions ◽  
Half Time ◽  
Consumption Growth ◽  
Co2 Consumption

Hydrogen production by cultivation of cyanobacteria in photobioreactors offers a clean and renewable alternative to thermochemical or electrolytic hydrogen production technologies with the added advantage of CO2 mitigation. The objective of this study is to experimentally investigate the CO2 consumption, growth, and H2 production of the cyanobacteria Anabaena variabilis ATCC 29413-U under atmosphere containing argon and CO2. Parameters investigated are irradiance and initial CO2 mole fraction in the gas phase. The CO2 consumption half-time, defined as the time at which the CO2 concentration in the gas phase decreases to half of its initial value, appears to be an appropriate time scale for modeling cyanobacterial CO2 consumption, growth, and H2 production. The half-time depends on both the initial CO2 mole fraction and the irradiance. Also, two regimes of growth have been identified depending on irradiance. Below 5,000 lux, the irradiance and the initial CO2 mole fraction have a coupled effect on cyanobacterial growth. Above 5,000 lux, growth depends only on the initial CO2 mole fraction. Furthermore, the optimum initial CO2 mole fraction around 0.05 has been identified for maximum growth and CO2 consumption rates. The growth and CO2 consumption were not inhibited by irradiance up to about 16,000 lux. Finally, the proposed empirical models can be used in conjunction with mass transfer and light transfer models to design and optimize the operating conditions of a photobioreactor for maximum hydrogen production and/or CO2 consumption.

The circulating floating bed reactor: effect of particle size distribution of the carrier on ammonia conversion

2000 ◽  
Vol 41 (4-5) ◽  
pp. 393-400 ◽  
Author(s):  
J.M. Garrido-Fernandez ◽  
R. Méndez ◽  
J.M. Lema ◽  
V. Lazarova
Keyword(s):  
Particle Size ◽  
Size Distribution ◽  
G Protein ◽  
Biomass Concentration ◽  
Biomass Accumulation ◽  
Ammonia Removal ◽  
Operating Conditions ◽  
Nitrification Rate ◽  
Ammonia Conversion ◽  
Biomass Activity

Three Circulating Floating Bed Reactors (CFBR) R1, R2 and R3 with 20% v/v of a plastic carrier with different size distribution were operated to study the effect of the particles size of the carrier on biomass accumulation and nitrification performance. Operating conditions were similar in the three systems: ammonia concentrations around 50 mg-N–NH4+/ L, ammonia loading rates up to 1.2 kg N–NH4+/m3·d and temperatures between 14 and 27°C. Accumulation of nitrite was observed until day 65th. This w as result both of the inhibition of nitrite oxidation by free ammonia until day 20th and the insignificant accumulation of a biomass with low nitrite oxidising capacity between days 20 and 65th. Ammonia conversion rate and removal efficiency were higher in the reactor with lower particle size, R3 (nitrification rate of 1.1 kg N–NH4+/m3·d and ammonia removal of 97% at 16°C), than in R2 or R1 (nitrification rate of 1.0 kg N–NH4+/m3·d and ammonia removal of 90% at 16°C). The better efficiency in R3 was obtained as a result of the higher specific surface of the biofilm developed. Biomass activity was similar in the three reactors (2.2 and 1.12 g N/g protein · d at 30 and 15°C, respectively). Both the biomass evolution with time and biomass retention in the systems was practically not influenced by the size of particle. Biomass concentration of 1.2 g protein/L was retained in the carrier and up to 20% of the newly produced biomass was retained in the CFBRs.

scholarly journals Catalytic Conversion of n-C7 Asphaltenes and Resins II into Hydrogen Using CeO2-Based Nanocatalysts

Nanomaterials ◽  
2021 ◽  
Vol 11 (5) ◽  
pp. 1301
Author(s):  
Oscar E. Medina ◽  
Jaime Gallego ◽  
Sócrates Acevedo ◽  
Masoud Riazi ◽  
Raúl Ocampo-Pérez ◽  
...  
Keyword(s):  
Hydrogen Production ◽  
Low Temperatures ◽  
Gaseous Mixture ◽  
H2 Production ◽  
The Other ◽  
Hydrogen Release ◽  
Catalytic Gasification ◽  
Three Samples ◽  
Main Decomposition ◽  
Catalytic Capacity

This study focuses on evaluating the volumetric hydrogen content in the gaseous mixture released from the steam catalytic gasification of n-C7 asphaltenes and resins II at low temperatures (<230 °C). For this purpose, four nanocatalysts were selected: CeO2, CeO2 functionalized with Ni-Pd, Fe-Pd, and Co-Pd. The catalytic capacity was measured by non-isothermal (from 100 to 600 °C) and isothermal (220 °C) thermogravimetric analyses. The samples show the main decomposition peak between 200 and 230 °C for bi-elemental nanocatalysts and 300 °C for the CeO2 support, leading to reductions up to 50% in comparison with the samples in the absence of nanoparticles. At 220 °C, the conversion of both fractions increases in the order CeO2 < Fe-Pd < Co-Pd < Ni-Pd. Hydrogen release was quantified for the isothermal tests. The hydrogen production agrees with each material’s catalytic activity for decomposing both fractions at the evaluated conditions. CeNi1Pd1 showed the highest performance among the other three samples and led to the highest hydrogen production in the effluent gas with values of ~44 vol%. When the samples were heated at higher temperatures (i.e., 230 °C), H2 production increased up to 55 vol% during catalyzed n-C7 asphaltene and resin conversion, indicating an increase of up to 70% in comparison with the non-catalyzed systems at the same temperature conditions.

Bifunctional single-atomic Mn sites for energy-efficient hydrogen production

Nanoscale ◽  
2021 ◽  
Author(s):  
Xianyun Peng ◽  
Junrong Hou ◽  
Yuying Mi ◽  
Jiaqiang Sun ◽  
Gaocan Qi ◽  
...  
Keyword(s):  
Hydrogen Production ◽  
Energy Saving ◽  
Hydrogen Evolution Reaction ◽  
Energy Efficient ◽  
Low Cost ◽  
Clean Energy ◽  
H2 Production ◽  
Energy Technology ◽  
Highly Active ◽  
Clean Energy Technology

Electrocatalytic hydrogen evolution reaction (HER) for H2 production is essential for future renewable and clean energy technology. Screening energy-saving, low-cost, and highly active catalysts efficiently, however, is still a grand...

scholarly journals Effect of magnetic field on biomass properties and their role in biodegradation under condition of low dissolved oxygen

2021 ◽  
Vol 11 (7) ◽  
Author(s):  
Nur Syamimi Zaidi ◽  
Johan Sohaili ◽  
Khalida Muda ◽  
Mika Sillanpää ◽  
Norelyza Hussein
Keyword(s):  
Magnetic Field ◽  
Dissolved Oxygen ◽  
Biomass Concentration ◽  
Aerobic Bacteria ◽  
Batch Reactors ◽  
Sequencing Batch Reactors ◽  
Great Chance ◽  
Sludge Bulking ◽  
The Magnetic Field ◽  
High Biomass Concentration

AbstractLow condition of dissolved oxygen (DO) is commonly associated with sludge bulking problem that was able to disrupt the efficiency of wastewater treatment performances. Relatively, very little attention was paid to the possibility of applying magnetic field in controlling the bulking problem. Hence, this study aims to investigate the performance of magnetic field on biomass properties and its effect on biodegradation under low condition of DO. Two continuous laboratory-scale sequencing batch reactors—Reactor A (SBRA) and Reactor B (SBRB)—were setup. SBRA was equipped with the magnetic device to exhibit magnetic field of 88 mT, while SBRB acted as a control system. The results showed that the biomass concentration in SBRA was higher compared to SBRB. High biomass concentration in SBRA resulted to better settleability with mean SVI of less than 30 mL/g. SBRA also showed consistently high removal performances of organic and inorganic contents compared to SBRB. These observations confirmed that the magnetic field was able to enhance the biomass properties, which further enhance the biodegradation ability of the aerobic bacteria under low DO condition. This also indicates that under the sludge bulking circumstances, the use of magnetic field stands a great chance in maintaining high biodegradation of the treatment system.

scholarly journals Zeolite addition to improve biohydrogen production from dark fermentation of C5/C6-sugars and Sargassum sp. biomass

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
R. M. Silva ◽  
A. A. Abreu ◽  
A. F. Salvador ◽  
M. M. Alves ◽  
I. C. Neves ◽  
...  
Keyword(s):  
Hydrogen Production ◽  
Anaerobic Bacteria ◽  
Dark Fermentation ◽  
Inorganic Materials ◽  
Biohydrogen Production ◽  
High Rate ◽  
Continuous Reactor ◽  
Organic Loading Rate ◽  
Fermentation Products ◽  
Zeolite Type

AbstractThermophilic biohydrogen production by dark fermentation from a mixture (1:1) of C5 (arabinose) and C6 (glucose) sugars, present in lignocellulosic hydrolysates, and from Sargassum sp. biomass, is studied in this work in batch assays and also in a continuous reactor experiment. Pursuing the interest of studying interactions between inorganic materials (adsorbents, conductive and others) and anaerobic bacteria, the biological processes were amended with variable amounts of a zeolite type-13X in the range of zeolite/inoculum (in VS) ratios (Z/I) of 0.065–0.26 g g−1. In the batch assays, the presence of the zeolite was beneficial to increase the hydrogen titer by 15–21% with C5 and C6-sugars as compared to the control, and an increase of 27% was observed in the batch fermentation of Sargassum sp. Hydrogen yields also increased by 10–26% with sugars in the presence of the zeolite. The rate of hydrogen production increased linearly with the Z/I ratios in the experiments with C5 and C6-sugars. In the batch assay with Sargassum sp., there was an optimum value of Z/I of 0.13 g g−1 where the H2 production rate observed was the highest, although all values were in a narrow range between 3.21 and 4.19 mmol L−1 day−1. The positive effect of the zeolite was also observed in a continuous high-rate reactor fed with C5 and C6-sugars. The increase of the organic loading rate (OLR) from 8.8 to 17.6 kg m−3 day−1 of COD led to lower hydrogen production rates but, upon zeolite addition (0.26 g g−1 VS inoculum), the hydrogen production increased significantly from 143 to 413 mL L−1 day−1. Interestingly, the presence of zeolite in the continuous operation had a remarkable impact in the microbial community and in the profile of fermentation products. The effect of zeolite could be related to several properties, including the porous structure and the associated surface area available for bacterial adhesion, potential release of trace elements, ion-exchanger capacity or ability to adsorb different compounds (i.e. protons). The observations opens novel perspectives and will stimulate further research not only in biohydrogen production, but broadly in the field of interactions between bacteria and inorganic materials.

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