The batch reactors were incubated in an incubator (Memmert, Model 30 -1060), where the temperature was maintained at thermophilic conditions of 54°C to accommodate the thermophilic archaeal culture. A high rate of magnetic stirring of 500 RPM was applied to the batch reactors to ensure continuous availability of H2 in the headspace to the entire culture without H2 mass transfer becoming the limiting factor for the conversion. The biocompatibility experiments were conducted over 4 periods with a randomized mix of different MDEA concentrations for each period, and fresh new extractions of inoculum from the anaerobic digester had been used for each period of the experiments. Additionally, two controls were included (1) a positive control with H2 and CO2 in the headspace, and (2) a biogas production control. These were included for each period to verify the activity of the inoculum and to subtract the CH4 produced from the degradation of residual biomasses from the mass balances.