2 INTERNATIONAL EURASIAN CONFERENCE ON SCIENCE, ENGINEERING AND TECHNOLOGY (EurasianSciEnTech 2020), Gaziantep, Türkiye, 7 - 09 Ekim 2020, ss.374-379
Increase in carbon dioxide and other greenhouse gases in the atmosphere are the main cause of global warming. The biggest impact of global warming is climate change. Syngas is a mixture of CO, CO2, N2, H2 and CH4 gases that are obtained through gasification and pyrolysis of biomass. Syngas fermentation results in production of ethanol and acetic acid from CO by a set of biochemical reactions known Wood-Ljungdahl pathway under anaerobic conditions. In this context, conversion of synthetic gas to bioethanol, which is an alternative biofuel to fossil fuels, is considered to be a promising approach in mitigating the negative effects of global warming by reducing greenhouse gas emissions.
The main driving argument of this study is to offer an economically sustainable basal media which is rich in trace elements, since the current commercial trace elements mixtures requires the purchase of highly expensive chemical components to prepare the required basal environment. Therefore, it is crucial to optimise the necessary recipe for trace element in order to reduce the potential production costs. For this purpose, Plackett Burman statistical method was used to select the most effective trace elements (Ni, Mg, Ca, Mn, Co, Cu, B, W, Zn, Fe and Mo) in batch experiments using Clostridium ljungdahlii at 37oC. As a result of 11 experimental sets which were determined by Plackett Burman method, an optimized trace element recipe was formulized. It was observed that the use of trace elements increased ethanol production approximately 3.5 times, the effect of Ni was negligible, and the model created was statistically significant (p = 0.0228 <0.05). Optimum trace element combination was determined to be as follows; 0.02 g/L Na2WO4 x 2H2O, 0.75 g/L FeSO4 x 7H2O, 0.02 g/L NiCl2 x 6H2O, 0.01 g/L MgSO4 x 7H2O, 0.79 g/L MnSO4 x H2O, 0.20 g/L CoCl2 x 6H2O, 0.01 g/L CuCl2 x 2H2O, 0.01 g/L H3BO3.
Keywords: Trace elements, Syngas fermentation, Bioethanol, Clostridium Ljungdahlii