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Confluence of Nanocatalysts and Bioenergy: An Overview of Microbial Electrochemical Systems and Biohydrogen Production
Published in Sonil Nanda, Prakash K. Sarangi, Biohydrogen, 2022
Piyush Parkhey, Kush Nayak, Reecha Sahu, Arunima Sur
As it became evident that fermentative hydrogen production has thermodynamic limitations to maximum yield, alternative approaches to enhance the biological hydrogen production were explored. The use of metal and metal oxide nanoparticles (NPs) has been advocated by many researchers to be an ideal practice to obtain higher biohydrogen yield. These NPs are proposed to increase hydrogen evolution in biological reactions by the following: Increasing the intracellular electron transfer.Supplementing the H2 evolving hydrogenase enzymes.Selectively promoting the growth of hydrogen producers in a mixed microflora.
Biochemical Pathways for the Biofuel Production
Published in Debabrata Das, Jhansi L. Varanasi, Fundamentals of Biofuel Production Processes, 2019
Debabrata Das, Jhansi L. Varanasi
The dark fermentation process, carried out by heterotrophic fermentative bacteria, produces biohydrogen at much higher rates compared to the biophotolysis or photofermentation processes (Manish and Banerjee 2008). Any organic substrates (from simple sugars to complex wastes) can be used for dark-fermentative hydrogen production. It is observed that facultative and obligate anaerobic bacteria can produce hydrogen using different metabolic pathways (Elsharnouby et al. 2013). The facultative anaerobes follow the pyruvate formate lyase (PFL) pathway, while the obligate anaerobes follow the pyruvate ferredoxin oxidoreductase (PFOR) pathway (Figure 4.5). In these pathways, the bacteria use the proton (H+) as the electron acceptor and disposes of the excess electrons in the form of molecular hydrogen (Das and Veziroglu 2008).
Physicochemical Properties of Biofuels
Published in M.R. Riazi, David Chiaramonti, Biofuels Production and Processing Technology, 2017
B. Brian He, Zhidan Liu, M.R. Riazi, David Chiaramonti
Hydrogen content in biohydrogen varies largely depending on the metabolic pathways in fermentation processes. Side reactions such as methanogenesis, homoacetogenesis, and lactate formation would consume the produced hydrogen and contribute to the loss of the hydrogen yield. These side reactions were related to the inoculum sources. Some of the bacteria known to produce hydrogen include strict anaerobes (Clostridiaceae), facultative anaerobes (Enterobacteriaceae and Klebsiella), and even aerobes (Bacillus spp., Aeromonons spp., Pseudomonas spp., and Vibrio spp.) (Ginkel et al., 2001; Wang and Wan, 2009; Lee et al., 2011). Among these, Clostridium and Enterobacter were most widely used in fermentative hydrogen production (Wang and Wan, 2009). Although pure microbes for hydrogen production were broadly studied, mixed cultures were recommended for their robustness and ease of acquisition, which include anaerobic sludge, aerobic activated sludge, granular sludge, wet soil, hydrogen-producing microorganism seeds, and anaerobic sludge from hydrogen production reactors. In order to harvest hydrogen-producing bacteria and suppress hydrogen-consuming bacteria, the pretreatment of the inoculum is necessary (Li and Fang, 2007). The simplest and most effective pretreatments are heat treatment and pH shock.
Characterization of a hydrogen-producing bacterium Clostridium sp. 5A-1
Published in International Journal of Green Energy, 2021
Jinling Cai, Renyao Wang, Qi Wu, Guangce Wang, Chaobing Deng
Biological hydrogen production is an environmental-friendly process and a promising hydrogen production technology. Hydrogen-producing microorganisms mainly include dark-fermentative bacteria, photo-fermentative bacteria, and algae. Dark-fermentative hydrogen production is considered as an ideal and environmental-friendly technology for producing renewable hydrogen fuel owing to its simpler reactor construction, high hydrogen production rate, low production cost, and light-independent procedure (Wang and Yin 2018). Numerous studies have been conducted to increase hydrogen production and decrease operational cost for the industrial application of fermentative hydrogen production. The major parameters examined include inoculum selection, operation conditions optimization, substrates utilization, and reactor design. Among them, bacterial strains play a crucial role in the hydrogen production system.
Progress in microbiology for fermentative hydrogen production from organic wastes
Published in Critical Reviews in Environmental Science and Technology, 2019
During the dark fermentative hydrogen production process, organic substrates are turned into hydrogen, volatile fatty acids and alcohols. These soluble metabolites can be further used in photo fermentation, enhancing the hydrogen yield of the whole hydrogen production process. Furthermore, with the addition of photo fermentation, organic wastes rich in acids and alcohols can also be used, resulting in an extension of substrate sources (Argun & Kargi, 2011). Two-phase dark and photo fermentation could achieve a theoretically maximum yield of 12 mol H2/mol hexose. Thus, the combination of dark and photo fermentation can achieve a dual benefit of hydrogen yield enhancement and effluent management (Miyake et al., 1984).
Enhanced fermentative hydrogen production from potato waste by enzymatic pretreatment
Published in Environmental Technology, 2022
Esma Mahfouf Bouchareb, Kerroum Derbal, Rayane Bedri, Souha Menas, Raouf Bouchareb, Nadir Dizge
Several factors can influence the obscure fermentation process, such as the choice of the raw material that is the most fundamental step towards ensuring the success of hydrogen production. Currently, different types of renewable biowaste have been used extensively as raw materials for fermentation. For example, crops and residual biomass (the first and second-generation biomass) [6,7]. Moreover, fermentative hydrogen production is a very complex process and is affected by many parameters, namely substrate, inoculum, reactor type, phosphate, nitrogen, metal ions, pH and temperature. The effects of these parameters on fermentative hydrogen production have been reported by several studies throughout the world in the last few years [8].