Biogas and hydrogen production from glycerol by Enterobacter aerogenes and anaerobic microbial communities
¹University of Latvia, Faculty of Biology, Department of Microbiology and Biotechnology, Jelgavas street 1, LV-1004 Riga, Latvia
²University of Latvia, Institute of Solid State Physics, Laboratory of Hydrogen Energy Materials, Kengaraga street 8, LV-1063 Riga, Latvia
Biological hydrogen production by anaerobic fermentation of widely available renewable resources is a promising and advantageous area. Using microbiological hydrogen production from crude glycerol biodiesel-derived waste was utilized by obtaining renewable energy carrier. The purpose of this research was to study biogas and hydrogen production by Enterobacter aerogenes MSCL 758 and by natural microbial communities. Growth medium was supplemented with analytical grade, technical grade or crude glycerol. Inoculants from old municipal landfill, manure and lake sludge were also used. Biogas production was analyzed using Automatic Methane Potential Test System II. Part of the experiments were carried out in serum bottles and evolved gases were tested using mass-spectrometry. Fluorescence in situ hybridization was used for bacterial population dynamic determination. Optimal concentration for crude glycerol was found to be six grams per liter. Amount of hydrogen was significantly higher and amount of nitrogen gas was lower in case of analytical grade glycerol usage in comparison to crude glycerol fermentation. E. aerogenes acted in synergy with landfill substrate and manure in biogas production from technical grade and analytical grade glycerol. It was not the case for crude glycerol usage. Addition of E. aerogenes increased overall amount of produced hydrogen. Obtained results showed potential of E. aerogenes for use in bioaugmentation purposes for fermentation of glycerol. Lake sludge inoculum contained microorganisms necessary for the production of hydrogen as well as biogas from glycerol. Clostridia and Gammaproteobacteria were predominant in the inoculum. Cultivable bacteria Bacillus licheniformis, Burkholderia cepacia, Hafnia alvei and unidentified Clostridium species were found to be predominant after six days of fermentation.