Assesment of The Effect of Immobilized Bioreactors on Bioethanol Production by Syngas Fermentation

Project no. 22039 · Status: Kapanmış · 2020

Summary

Bioethanol, one of the promising sources among clean energy sources, is produced biologically from first and second generation sources. Within the scope of the project, it is aimed to ensure that the source used in bioethanol production is waste gas and thus the first generation sources such as corn, wheat, sugar cane to be used only as food. Thus, it is aimed not to deprive people of their right to reach sufficient food. Syngas is a mixture of gases containing CO, CO2, N2, H2 and CH4. The biotechnological conversion of syngas to valuable product such as ethanol, acetate is called syngas fermentation. Two bacterial species, Clostridium ljungdahlii and Clostridium ragsdalei, which are very important for syngas fermentation, were used within the scope of the project. In the project, firstly, the bioethanol production conditions from Syngas were optimized in batch reactors with syngas fermentation using Clostridium ljungdahlii. It has been observed that ethanol production yields can be increased by 1.2-2.5 times with the trace element study performed with Clostridium ljungdahlii. In the optimization study using the Plackett-Burman method, it was observed that W is the most important element in ethanol production for Clostridium ljungdahlii. It has been calculated that the cost of the trace element solution can be reduced by 22% for the optimized media composition. This result is very important in terms of reducing process costs. After the optimum environment was determined, synthesis gas fermentation studies were carried out in the immobilized reactor in order to increase the CO mass transfer efficiency. Biochar, which is produced by carbonization of the organic structure of the biomass as a result of thermochemical pyrolysis and gasification, and which has a very large surface area with its porous structure, was used as the immobilized material. While acetic acid production was observed in the batch feed reactor using Clostridium ljungdahlii and the continuous feed reactor using Clostridium ragsdalei, ethanol production was not observed. As a result of the adsorption isotherm study, it was observed that the olive seed biochar used as the immobilized material adsorbs the ethanol produced. Mineral analysis results for biochar showed the presence of many minerals (Mg, Al, Si, P, S, Cl, K, Ca, Ti, Cr, Fe, Cu, Zn, Na, C). Olive seed biochar has been characterized by values far below the amount of elements found in the growth media of the microorganisms used. The results of the analysis showed that the olive seed biochar used did not have elemental content that would cause a toxic effect on the microorganism. With this project, a new approach has been brought to the production of bioethanol, which is an environmentally friendly renewable energy source against the climate crisis, to increase the process efficiency economically with immobilized bioreactors and to obtain a product with high added value by capturing carbon from the flue gases, contributing to the literature for future studies.

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