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Bio-based Products in Fuel Cells
Published in Lakhveer Singh, Durga Madhab Mahapatra, Waste to Sustainable Energy, 2019
Beenish Saba, Ann D. Christy, Kiran Abrar, Tariq Mahmood
Mohanakrishna et al. (2016) constructed a H-type dual-chambered MEC reactor by following two-stage operation. Gaseous CO2 was used as a substrate source. In the first stage, optimization of two cathodic potential −600 mV to −800 mV was done utilizing bicarbonates as a carbon source. Enriched acetogenic bacteria were used as a biocatalyst in the second stage. At −800 mV, acetate generation was maximum. A large scale biochemical system was created by using Clostridium ljungdahlii as an inoculum source. Gaseous CO2 was used as a substrate and resulted in a variety of bio-based products, e.g., formic, acetic, propionic acids; methanol, and ethanol (Christodouloua et al. 2017). A detailed summary of substrates and microbes used in MECs is presented in Table 4.1.
Industrial biotechnology
Published in Firdos Alam Khan, Biotechnology Fundamentals, 2018
Clostridium is a genus of Gram-positive bacteria, belonging to the Firmicutes. These are obligate anaerobes capable of producing endospores. Individual cells are rod-shaped, which gives them their name, from the Greek kloster or spindle. These characteristics traditionally defined the genus; however, many species originally classified as Clostridium have been reclassified in other genera. Clostridium thermocellum can utilize lignocellulosic waste and generate ethanol, thus making it a possible candidate for use in ethanol production. It also has no oxygen requirement and is thermophilic, thus reducing cooling cost. Clostridium acetobutylicum, also known as the Weizmann organism, was first used by Chaim Weizmann in 1916 to produce acetone and biobutanol from starch for the production of gunpowder and TNT. The anaerobic bacterium Clostridium ljungdahlii, recently discovered in commercial chicken wastes, can produce ethanol from single-carbon sources, including synthesis gas, a mixture of carbon monoxide and H2 that can be generated from the partial combustion of either fossil fuels or biomass. Use of these bacteria to produce ethanol from synthesis gas has progressed to the pilot plant stage at the BRI Energy facility in Fayetteville, Arkansas. Genes from Clostridium thermocellum have been inserted into transgenic mice to allow the production of endoglucanase. The experiment was intended to learn more about how the digestive capacity of monogastric animals could be improved.
Biological Process for Butanol Production
Published in Jay J. Cheng, Biomass to Renewable Energy Processes, 2017
Maurycy Daroch, Jian-Hang Zhu, Fangxiao Yang
In recent years syngas fermentation emerged as one of the most promising waste to biofuels technologies (Dürre, 2016; Green, 2011; Jiang et al., 2015). With initial success of syngas to ethanol technology developed by Lanzatech using C. autoethanogenum and INEOS Bio using Clostridium ljungdahlii, interest in producing other bioproducts is high. Both companies are employing syngas to ethanol fermentation as a main process and progressively working towards biobutanol and other products using systems-level metabolic engineering approaches combined with chemical engineering. It is expected that syngas to biobutanol technologies can bring down the costs of biobutanol production at least by a factor of two when compared to traditional ABE fermentation using corn or molasses as feedstock (Jiang et al., 2015).
Waste into energy conversion technologies and conversion of food wastes into the potential products: a review
Published in International Journal of Ambient Energy, 2021
Jeya Jeevahan, A. Anderson, V. Sriram, R. B. Durairaj, G. Britto Joseph, G. Mageshwaran
An alternative method is the use of microorganisms for converting syngas into bioethanol. In 1987, anaerobic bacteria, named Clostridium ljungdahlii, was discovered which had the ability to ferment carbon monoxide and hydrogen into ethanol and acetic acid. It had opened the opportunities to develop microorganisms for syngas fermentation process. Some of the other important microorganisms, such as C. ljungdahlii, C. carboxidivorans, Alkalibaculum bacchi and C. ragsdalei serve as biocatalysts, also act as good biocatalysts. In this method, syngas is first passed through a series of filters to remove tar and other solid particles. The filtered syngas is then fermented by microbial catalysts. The process produces several products such as organic acids (acetic, propionic, butyric, formic and lactic acids) and alcohols (methanol, ethanol, propanol and butanol). The process parameters are optimised for maximising the production of ethanol. The process has advantages over FT method. It has higher yield and produces less toxic substances. H2/CO ratio need not be fixed which eliminates separate reactor vessels for carrying out each process. Syngas fermentation takes place at near ambient temperature (Munasinghe and Khanal 2010; Abubackar, Veiga, and Kennes 2011; Martin et al. 2016). The overall reactions to convert syngas to ethanol are shown below.
Ethanol production by syngas fermentation in a continuous stirred tank bioreactor using Clostridium ljungdahlii
Published in Biofuels, 2019
Bimal Acharya, Animesh Dutta, Prabir Basu
During the fermentation process, carbon monoxide is converted into ethanol, acetate and carbon dioxide through the wood–ljungdahl pathway using biocatalyst Clostridium ljungdahlii. Supplied gas carbon monoxide and hydrogen are useful for the cell growth of the microorganism. The concentration of carbon monoxide continuously decreases with the increase in concentration of carbon dioxide [16,18]. Carbon dioxide may react with the hydrogen as an electron donor to yield ethanol and acetate.