scholarly journals Impacts of Syngas Composition on Anaerobic Fermentation

Reactions ◽  
2021 ◽  
Vol 2 (4) ◽  
pp. 391-407
Author(s):  
Carolina Benevenuti ◽  
Priscilla Amaral ◽  
Tatiana Ferreira ◽  
Peter Seidl
Keyword(s):  
Anaerobic Fermentation ◽  
Anaerobic Bacteria ◽  
Gaseous Mixture ◽  
Product Formation ◽  
Molar Ratio ◽  
Thermochemical Conversion ◽  
Syngas Fermentation ◽  
Municipal Solid Wastes ◽  
Nitrogenous Compounds ◽  
Waste Coal

Energy consumption places growing demands on modern lifestyles, which have direct impacts on the world’s natural environment. To attain the levels of sustainability required to avoid further consequences of changes in the climate, alternatives for sustainable production not only of energy but also materials and chemicals must be pursued. In this respect, syngas fermentation has recently attracted much attention, particularly from industries responsible for high levels of greenhouse gas emissions. Syngas can be obtained by thermochemical conversion of biomass, animal waste, coal, municipal solid wastes and other carbonaceous materials, and its composition depends on biomass properties and gasification conditions. It is defined as a gaseous mixture of CO and H2 but, depending on those parameters, it can also contain CO2, CH4 and secondary components, such as tar, oxygen and nitrogenous compounds. Even so, raw syngas can be used by anaerobic bacteria to produce biofuels (ethanol, butanol, etc.) and biochemicals (acetic acid, butyric acid, etc.). This review updates recent work on the influence of biomass properties and gasification parameters on syngas composition and details the influence of these secondary components and CO/H2 molar ratio on microbial metabolism and product formation. Moreover, the main challenges, opportunities and current developments in syngas fermentation are highlighted in this review.

scholarly journals Influences of the Pretreatments of Residual Biomass on Gasification Processes: Experimental Devolatilizations Study in a Fluidized Bed

2021 ◽  
Vol 11 (12) ◽  
pp. 5722
Author(s):  
Stefania Lucantonio ◽  
Andrea Di Giuliano ◽  
Katia Gallucci
Keyword(s):  
Fluidized Bed ◽  
Molar Ratio ◽  
Thermochemical Conversion ◽  
Chemical Looping ◽  
Carbon Conversion ◽  
European Research ◽  
Residual Biomass ◽  
General Improvement ◽  
Straight Lines ◽  
Integral Average

The European research project CLARA (chemical looping gasification for sustainable production of biofuels, G.A. 817841) investigated chemical looping gasification of wheat straw pellets. This work focuses on pretreatments for this residual biomass, i.e., torrefaction and torrefaction-washing. Devolatilizations of individual pellets were performed in a laboratory-scale fluidized bed made of sand, at 700, 800, and 900 °C, to quantify and analyze the syngas released from differently pretreated biomasses; experimental data were assessed by integral-average parameters: gas yield, H2/CO molar ratio, and carbon conversion. A new analysis of devolatilization data was performed, based on information from instantaneous peaks of released syngas, by simple regressions with straight lines. For all biomasses, the increase of devolatilization temperature between 700 and 900 °C enhanced the thermochemical conversion in terms of gas yield, carbon conversion, and H2/CO ratio in the syngas. Regarding pretreatments, the main evidence is the general improvement of syngas quality (i.e., composition) and quantity, compared to those of untreated pellets; only slighter differentiations were observed concerning different pretreatments, mainly thanks to peak quantities, which highlighted an improvement of the H2/CO molar ratio in correlation with increased torrefaction temperature from 250 to 270 °C. The proposed methods emerged as suitable straightforward tools to investigate the behavior of biomasses and the effects of process parameters and biomass nature.

scholarly journals Carbon source utilization and hydrogen production by isolated anaerobic bacteria

2016 ◽  
Vol 9 (1) ◽  
pp. 62-67 ◽  
Author(s):  
R. Jame ◽  
V. Zelená ◽  
B. Lakatoš ◽  
Ľ. Varečka
Keyword(s):  
Carbon Source ◽  
Anaerobic Fermentation ◽  
Carbon Sources ◽  
Anaerobic Bacteria ◽  
Growth Yield ◽  
Bacterial Isolates ◽  
Carbon Source Utilization ◽  
Bacterial Strains ◽  
Monocarboxylic Acids ◽  
Sheep Rumen

Abstract Five bacterial isolates were tested for their ability to generate hydrogen during anaerobic fermentation with various carbon sources. One isolate from sheep rumen was identified as Escherichia coli and four isolates belonged to Clostridium spp. Glucose, arabinose, ribose, xylose, lactose and cellobiose were used as carbon sources. Results showed that all bacterial strains could utilize these compounds, although the utilization of pentoses diminished growth yield. The excretion of monocarboxylic acids (acetate, propionate, formiate, butyrate) into medium was changed after replacing glucose by other carbon sources. Di- and tricarboxylic acids were excreted in negligible amounts only. Spectra of excreted carboxylic acids were unique for each strain and all carbon sources. All isolates produced H2 between 4—9 mmol·L−1 during the stationary phase of growth with glucose as energy source. This value was dramatically reduced when pentoses were used as carbon source. Lactose and cellobiose, starch and cellulose were suitable substrates for the H2 production in some but not all isolates. No H2 was produced by proteinaceous substrate, such as blood. Results show that both substrate utilization and physiological responses (growth, excretion of carboxylates, H2 production) are unique functions of each isolate.

scholarly journals Proteome Analysis of Streptococcus thermophilus Grown in Milk Reveals Pyruvate Formate-Lyase as the Major Upregulated Protein

2005 ◽  
Vol 71 (12) ◽  
pp. 8597-8605 ◽  
Author(s):  
Sylviane Derzelle ◽  
Alexander Bolotin ◽  
Michel-Yves Mistou ◽  
Françoise Rul
Keyword(s):  
Anaerobic Fermentation ◽  
Physiological Role ◽  
Proteome Analysis ◽  
Streptococcus Thermophilus ◽  
Product Formation ◽  
Exponential Growth Phase ◽  
Transcriptional Level ◽  
Acid Product ◽  
Pyruvate Formate Lyase ◽  
Proteomic Approach

ABSTRACT We investigated the adaptation to milk of Streptococcus thermophilus LMG18311 using a proteomic approach. Two-dimensional electrophoresis of cytosolic proteins were performed after growth in M17 medium or in milk. A major modification of the proteome concerned proteins involved in the supply of amino acids, like the peptidase PepX, and several enzymes involved in amino acid biosynthesis. In parallel, we observed the upregulation of the synthesis of seven enzymes directly involved in the synthesis of purines, as well as formyl-tetrahydrofolate (THF) synthetase and serine hydroxy-methyl transferase, two enzymes responsible for the synthesis of compounds (THF and glycine, respectively) feeding the purine biosynthetic pathway. The analysis also revealed a massive increase in the synthesis of pyruvate formate-lyase (PFL), the enzyme which converts pyruvate into acetyl coenzyme A and formate. PFL has been essentially studied for its role in mixed-acid product formation in lactic acid bacteria during anaerobic fermentation. However, formate is an important methyl group donor for anabolic pathway through the formation of folate derivates. We hypothesized that PFL was involved in purine biosynthesis during growth in milk. We showed that PFL expression was regulated at the transcriptional level and that pfl transcription occurred during the exponential growth phase in milk. The complementation of milk with formate or purine bases was shown to reduce pfl expression, to suppress PFL synthesis, and to stimulate growth of S. thermophilus. These results show a novel regulatory mechanism controlling the synthesis of PFL and suggest an unrecognized physiological role for PFL as a formate supplier for anabolic purposes.

scholarly journals Insight into the Ex Situ Catalytic Pyrolysis of Biomass over Char Supported Metals Catalyst: Syngas Production and Tar Decomposition

Nanomaterials ◽  
2020 ◽  
Vol 10 (7) ◽  
pp. 1397 ◽  
Author(s):  
Mian Hu ◽  
Baihui Cui ◽  
Bo Xiao ◽  
Shiyi Luo ◽  
Dabin Guo
Keyword(s):  
Active Sites ◽  
Catalytic Pyrolysis ◽  
Supported Catalyst ◽  
Ex Situ ◽  
Molar Ratio ◽  
Ni Catalyst ◽  
Nitrogenous Compounds ◽  
Syngas Production ◽  
Valence States ◽  
Pyrolysis Of Biomass

Ex situ catalytic pyrolysis of biomass using char-supported nanoparticles metals (Fe and Ni) catalyst for syngas production and tar decomposition was investigated. The characterizations of fresh Fe-Ni/char catalysts were determined by TGA, SEM–EDS, Brunauer–Emmett–Teller (BET), and XPS. The results indicated that nanoparticles metal substances (Fe and Ni) successfully impregnated into the char support and increased the thermal stability of Fe-Ni/char. Fe-Ni/char catalyst exhibited relatively superior catalytic performance, where the syngas yield and the molar ratio of H2/CO were 0.91 Nm3/kg biomass and 1.64, respectively. Moreover, the lowest tar yield (43.21 g/kg biomass) and the highest tar catalytic conversion efficiency (84.97 wt.%) were also obtained under the condition of Ni/char. Ultimate analysis and GC–MS were employed to analyze the characterization of tar, and the results indicated that the percentage of aromatic hydrocarbons appreciably increased with the significantly decrease in oxygenated compounds and nitrogenous compounds, especially in Fe-Ni/char catalyst, when compared with no catalyst pyrolysis. After catalytic pyrolysis, XPS was employed to investigate the surface valence states of the characteristic elements in the catalysts. The results indicated that the metallic oxides (MexOy) were reduced to metallic Me0 as active sites for tar catalytic pyrolysis. The main reactions pathway involved during ex situ catalytic pyrolysis of biomass based on char-supported catalyst was proposed. These findings indicate that char has the potential to be used as an efficient and low-cost catalyst toward biomass pyrolysis for syngas production and tar decomposition.

Kinetics of accelerated solid-state fermentation of organic-rich municipal solid waste

2000 ◽  
Vol 41 (3) ◽  
pp. 231-238 ◽  
Author(s):  
E.R. Viéitez ◽  
J. Mosquera ◽  
S. Ghosh
Keyword(s):  
Solid State ◽  
Solid State Fermentation ◽  
Anaerobic Fermentation ◽  
Landfill Gas ◽  
Product Formation ◽  
Hydrolysis Rate ◽  
Methane Formation ◽  
Effluent Recirculation ◽  
Rapid Hydrolysis ◽  
Biphasic Process

Biotransformation of landfill solid wastes is a slow process requiring decades for completion. Accelerated anaerobic fermentation in modulated landfill environments may alleviate or eliminate pollution of land, water and air. This research was undertaken to demonstrate the application of biphasic fermentation to a simulated laboratory-scale landfill to effect rapid biomethanation of biodegradable solids. The biphasic process consisted of solid-state, acidogenic fermentation of the organic fraction of MSW followed by biomethanation of acidic hydrolysates in a separate methane fermenter. Solid-state fermentation of the MSW with effluent recirculation resulted in rapid hydrolysis, acidification and denitrification, with soluble COD and VFA concentrations accumulating to inhibitory levels of 60,000 mg/l and 13,000 mg/l, respectively, at a pH of 4.5. The landfill gas methane concentration reached a maximum of 55 mol.%. By comparison, the methanogenic reactor produced high methane-content (70–85 mol.%) gases. The biphasic process effected carbohydrate, lipid, and protein conversion efficiencies of 90%, 49%, and 37%, respectively. Development of a Monod-type product-formation model was undertaken to predict methane formation and to determine kinetic parameters for the methanogenic processes in the simulated landfill and separate methane reactors. A first-order solids hydrolysis rate constant of 0.017 day−1 was evaluated to show that landfill solids hydrolysis was slower than the inhibited methanogenesis rate.

scholarly journals Gasification of Densified Biomass (DB) and Municipal Solid Wastes (MSW) Using HTA/SG Technology

Processes ◽  
2021 ◽  
Vol 9 (12) ◽  
pp. 2178
Author(s):  
Jan A. Stasiek ◽  
Jacek Baranski ◽  
Marcin Jewartowski ◽  
Jan Wajs
Keyword(s):  
High Temperature ◽  
Rapid Development ◽  
Fixed Bed ◽  
Calorific Value ◽  
Steam Gasification ◽  
Municipal Waste ◽  
Thermochemical Conversion ◽  
Municipal Solid Wastes ◽  
Extraction Technology ◽  
Production Of Hydrogen

The necessity of economical and rational use of natural energy sources caused a rapid development of research on the possibilities of using non-conventional energy resources. Taking the above into account, a new technological process of thermochemical conversion of biomass and communal waste, commonly known as High Temperature Air/Steam Gasification (HTA/SG) and Multi-Staged Enthalpy Extraction Technology (HTAG-MEET), was developed. In relation to traditional techniques of gasification or combustion of hydrocarbon fuels, the presented concept is characterized by higher thermal efficiency of the process, low emission of harmful compounds of carbon, sulfur, nitrogen, dioxins, furans and heavy metals. The use of a high-temperature gasification factor causes an increased thermochemical decomposition of solid fuels, biomass and municipal waste into gaseous fuel (syngas), also with increased hydrogen content and Lower Calorific Value (LCV). In this study, the possibility of using a batch type reactor (countercurrent gasifier) was analyzed for gasification of biomass and municipal waste in terms of energy recovery and environmental protection. The proposed research topic was aimed at examining the possibility of using the thermal utilization of biomass and municipal waste through their high-temperature decomposition in the presence of air, a mixture of air and steam. The main goals of the research were achieved during the implementation of several parallel stages of the schedule, which included, primarily: (a) study of the possibility of using thermal utilization of biomass and municipal waste through their high-temperature gasification in the presence of air or a mixture of air and steam and, secondary (b) analytical and numerical modeling of high-temperature gasification of biomass and municipal waste with the use of ANSYS CFD Fluent 6.3 software. Selected results of the experimental and numerical studies are properly presented. The higher temperature gasification concept shows the capability of this technology for maximizing the gaseous product yield in an up-draft fixed bed gasifier. It was also observed that at a high temperature, steam addition contributed to the thermal conversion of biofuels to gas with higher production of hydrogen.

scholarly journals Experimental study on characteristics of municipal solid waste (MSW) in typical cites of Indonesia

2020 ◽  
Vol 8 (1) ◽  
pp. 13
Author(s):  
Zongao Zhen ◽  
Hao Zhang ◽  
Mi Yan ◽  
Angjian Wu ◽  
Xiaoqing Lin ◽  
...  
Keyword(s):  
Municipal Solid Waste ◽  
Solid Waste ◽  
Chemical Properties ◽  
Thermochemical Conversion ◽  
Clear Understanding ◽  
Municipal Solid Wastes ◽  
Renewable Power ◽  
Physical Composition ◽  
Energy Products ◽  
The Impact

<p>A clear understanding of the basic characteristics of municipal solid waste is the basis for the investigation of appropriate disposal technique. Municipal solid wastes subdivided into 7 categories were sampled in 7 typical cities of Indonesia in this study. The physical composition, chemical properties of the municipal solid waste, as well as the impact of seasonal and geographical changes on the physical composition have been investigated. The physical and chemical characteristics of municipal solid waste in Indonesia is understood in detail.<br />The average percent content of each Indonesian waste category in sequence is 27.50% food waste, 20.42% mixture waste, 19.41% plastic waste, 14.54% paper waste, 9.25% wood waste, 4.90% textile waste, and 3.98% non-combustible waste. It is found that the seasonal changes have weak impact on the composition of MSW in Indonesia. The moisture content of each type of waste is above 30%, and the lower heating value on a wet basis of the overall municipal solid waste reaches 8.6MJ/Kg, which is well above the World Bank-recommended value (6MJ/Kg) for utilization in thermochemical conversion processes. The results prove that Indonesian municipal solid waste is potential for converting waste to renewable power or other energy products.</p>

scholarly journals Connecting lignin gasification with syngas fermentation

2020 ◽  
Author(s):  
Eleni Liakakou ◽  
Alba Infantes ◽  
Berend Vreugdenhil ◽  
Anke Neumann
Keyword(s):  
Fermentation Process ◽  
Anaerobic Fermentation ◽  
Beech Wood ◽  
Added Value ◽  
Attractive Alternative ◽  
Syngas Fermentation ◽  
Clostridium Ljungdahlii ◽  
Stage Of Development ◽  
Gas Fermentation ◽  
Product Gas

The development of lignin derived energy products is one way to increase the value of biorefinery residues, which is the scope of the EU project AMBITION. Gasification of (lignin-rich) biorefinery residues, followed by product gas cleaning and anaerobic fermentation, offers a potential to produce higher added-value products such as biofuels and chemicals. MILENA indirect gasification allows complete fuel conversion and produces a high value gas composed of CO, H2 and CO2, as well as compounds such as CH4, C2-C4 gases, benzene, toluene and xylene (BTX). The separation of the most valuable components of the product gas is a good way to maximize the value from the feedstock via co-production schemes. The product gas, after appropriate cleaning to remove impurities that can reduce the fermentability of syngas, can be applied in the gas fermentation process. Some anaerobic microorganisms, known as acetogens, can be used as a biocatalyst for the conversion of syngas into short-chain organic acids and alcohols, like acetate, ethanol, butanol, butan-2,3-diol and butyric acid. The ability of these microorganisms to withstand some of the impurities contained in the syngas and their flexibility to use different mixtures of CO and/or CO2 and H2 makes these bacteria an attractive alternative to the chemical catalytic processes. Despite these advantages, the integration of gasification with syngas fermentation is still in an early stage of development, where many questions exist concerning the syngas quality needed in the fermentation process. The challenge is to define the optimum gasification conditions for this type of feedstock that will provide a H2:CO:CO2 ratio at values suitable for syngas fermentation, as well as to identify and remove the compounds that can inhibit the performance of the microorganisms. In this work a first attempt to combine the two processes is presented.A lignin rich feedstock was gasified with steam at 780°C using MILENA indirect gasifier, at TNO. The product gas after removal of the main impurities, consisted of CO, H2, CO2, N2, CH4 and traces of other gaseous hydrocarbons, benzene and H2S. The influence of the obtained syngas quality and composition was evaluated in the fermentation process, at KIT. For comparison, product gas from beech wood gasification after cleaning was also evaluated in the fermentation process under the same conditions.The process involved growing cells in a batch system under continuous flow of biomass-derived gas. The strain used in this work is Clostridium ljungdahlii. The fermentation of both beech wood and lignin-derived syngas was successful, since no inhibition was observed. The carbon fixation onto products achieved for both cases was approximately 55%, while a slightly higher ethanol production was observed with the lignin-derived syngas. The total productivity (including both acetate and ethanol) at the end-point was 0.18 g/L/h for both fermentations.

scholarly journals Effect of Oxygen Contamination on Propionate and Caproate Formation in Anaerobic Fermentation

2021 ◽  
Vol 9 ◽  
Author(s):  
Flávio C. F. Baleeiro ◽  
Magda S. Ardila ◽  
Sabine Kleinsteuber ◽  
Heike Sträuber
Keyword(s):  
Metabolic Networks ◽  
Community Dynamics ◽  
Bubble Column ◽  
Anaerobic Fermentation ◽  
Product Formation ◽  
Chain Elongation ◽  
Strictly Anaerobic ◽  
Production Rates ◽  
Air Contamination ◽  
Butyrate Production

Mixed microbial cultures have become a preferred choice of biocatalyst for chain elongation systems due to their ability to convert complex substrates into medium-chain carboxylates. However, the complexity of the effects of process parameters on the microbial metabolic networks is a drawback that makes the task of optimizing product selectivity challenging. Here, we studied the effects of small air contaminations on the microbial community dynamics and the product formation in anaerobic bioreactors fed with lactate, acetate and H2/CO2. Two stirred tank reactors and two bubble column reactors were operated with H2/CO2 gas recirculation for 139 and 116 days, respectively, at pH 6.0 and 32°C with a hydraulic retention time of 14 days. One reactor of each type had periods with air contamination (between 97 ± 28 and 474 ± 33 mL O2 L−1 d−1, lasting from 4 to 32 days), while the control reactors were kept anoxic. During air contamination, production of n-caproate and CH4 was strongly inhibited, whereas no clear effect on n-butyrate production was observed. In a period with detectable O2 concentrations that went up to 18%, facultative anaerobes of the genus Rummeliibacillus became predominant and only n-butyrate was produced. However, at low air contamination rates and with O2 below the detection level, Coriobacteriia and Actinobacteria gained a competitive advantage over Clostridia and Methanobacteria, and propionate production rates increased to 0.8–1.8 mmol L−1 d−1 depending on the reactor (control reactors 0.1–0.8 mmol L−1 d−1). Moreover, i-butyrate production was observed, but only when Methanobacteria abundances were low and, consequently, H2 availability was high. After air contamination stopped completely, production of n-caproate and CH4 recovered, with n-caproate production rates of 1.4–1.8 mmol L−1 d−1 (control 0.7–2.1 mmol L−1 d−1). The results underline the importance of keeping strictly anaerobic conditions in fermenters when consistent n-caproate production is the goal. Beyond that, micro-aeration should be further tested as a controllable process parameter to shape the reactor microbiome. When odd-chain carboxylates are desired, further studies can develop strategies for their targeted production by applying micro-aerobic conditions.

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