The Importance of Hydrogen in Landfill Fermentations
Forty-two samples taken from two landfills were monitored for CH4 production and apparent steady-state H2 concentration. The rates of methanogenesis in these samples ranged from below the detection limit to 1,900 μmol kg (dry weight)-1 day-1, and the median steady-state hydrogen concentration was 1.4 μM in one landfill and 5.2 μM in the other. To further investigate the relationship between hydrogen concentration and methanogenesis, a subset of seven landfill samples was selected on basis of their rates of CH4 production, H2 concentrations, sample pHs, and moisture contents. Samples with H2 concentrations of < 20 nM had relatively small amounts of volatile fatty acids (VFAs) (undetectable to 18.6 mmol of VFA kg [dry weight]-1), while samples with H2 concentrations of > 100 nM had relatively high VFA levels (133 to 389 mmol of VFA kg [dry weight]-1). Samples with high H2 and VFA contents had relatively low pH values (≤6.3). However, methanogenic and syntrophic bacteria were present in all samples, so the lack of methanogenesis in some samples was not due to a lack of suitable inocula. The low rates of methanogenesis in these samples were probably due to inhibitory effects of low pH and VFA accumulation, resulting from a thermodynamic uncoupling of fatty acid oxidation. As in other anaerobic ecosystems, H2 is a critical intermediate that may be used to monitor the status of landfill fermentations.
M. R. Mormile et al., "The Importance of Hydrogen in Landfill Fermentations," Applied and Environmental Microbiology, vol. 62, no. 5, pp. 1583-1588, American Society for Microbiology, May 1996.
Keywords and Phrases
Hydrogen; Methane; Volatile Fatty Acid; Fatty Acid Oxidation; Fermentation; Landfill; Methanobacterium; Methanogenesis; Microbiology; Nonhuman; pH
International Standard Serial Number (ISSN)
Article - Journal
© 1996 American Society for Microbiology, All rights reserved.