Alternative methods for dark fermentation course analysis

Abstract

Dark fermentation course analysis is crucial, as complexed matrix of gaseous components may be formed and revealed during the process. The paper considers key issues related to the microbiological process in which complex organic substances are transformed into hydrogen. For the purposes of hydrogen generation, the application of wastewater mixed sludge pre-treated according to Faloye method (Faloye et al. in Int J Hydrog Energy 38:11765–11773, 2013. https://doi.org/10.1016/j.ijhydene.2013.06.129; Int J Hydrog Energy 39:5607–5616, 2014. https://doi.org/10.1016/j.ijhydene.2014.01.163) was applied. The main risk of by-product formation is related to the presence of methanogens, i.e., Archea, in the sludge. The application of gaseous chromatography confirmed the presence of hydrogen during the initial, lag and log phases of the culture and methane in the late logarithmic death phase of the culture. However, other fermentation gaseous products’ presence was not confirmed, as their concentration was under the limit of detection. Therefore, a revision regarding the application of matrix sensors was proposed, and the levels of gases able to be measured using both gas chromatography and matrix sensors were conducted. The criteria of matrix sensors’ selection should include the selectivity not only for the hydrogen, hydrogen sulfide or methane, but also the sensitivity to the response of other gases contained in the mixture—ammonium, carbon dioxide and oxygen. A comprehensive combination of commercially available sensors and their applicability for the purposes of dark fermentation course analysis was presented on the basis of the levels of gas concentrations in the generated gas mixture.