Hydrogen-dependent control of the continuous thermophilic anaerobic digestion process using membrane inlet mass spectrometry

The control of a thermophilic continuous anaerobic digestion system when subjected to potential inhibitory shock loadings was achieved through the regulation of dissolved H₂, monitored using membrane inlet mass spectrometry, by the controlled addition of carbon source. At a feed pump switching threshold equivalent to 1 μmol/1 H₂ a steady state rate of methanogenesis of approximately 40 μmol/1/min was obtained. Higher H₂ thresholds resulted in an inhibition of methanogenesis, but precise control of H₂ concentration was demonstrated with an oscillatory response of period 2·5–5·0 min.