The biocompatibility and the microbial uptake kinetics of substrates in the batch reactors were quantified and evaluated according to a method, which previously has been used and described in other batch-related biomethanation studies . The stochiometric 4:1 consumption of H2 and CO2 to generate CH4 (reaction 3) creates a four-fold pressure drop (as CO2 is already absorbed in the solvent), which was utilized to determine the substrate uptake kinetics. Hence, the batch reactors were fitted with analogue pressure sensors (MPX4250AP, CASE 867B-04, NPX) with an A/D-converter (MCP3423E/SL, Microchip) to quantify and continuously record the pressure profiles with a customized LabView interface. The pressure profiles resembled inverted sigmoidal curves, where the beginning of the experiment was characterized by a lagphase, which was followed by zero-order kinetics with a linear slope of pressure drop. The correlation between the rate of the pressure drops and the maximum specific H2 consumption rate and CH4 production rate was derived from the ideal gas equation and reaction stochiometric of H2 and CO2 conversion to CH4 supplemented by gas chromatographic analysis of the gaseous headspace at the start and end of each incubation period.