Process analysis of biological Sabatier reaction for bio-methane production

• Simulation study of biological Sabatier reaction for biogas upgrading.
• Mathematical modeling of biological Sabatier reaction.
• Factorial design of biological Sabatier reaction and stability study.
• Response surface methodology of biological Sabatier reaction and mathematical model of methane evolution rate.

The biological conversion of H2 and CO2 into CH4, using methanogenic archaea is an interesting technology for CO2 conversion, energy storage and biogas upgrading. For an industrial application of this process the optimization of volumetric productivity and product quality are an important issues. This work aims to investigate the effects of temperature, gassing rate, gassing ratio (H2/CO2), reactor pressure on performance of Methanothermobacter marburgensis through anova analysis. The process is simulated and analyzed using the ChemCad 6.3® and the Sabatier reaction is modeled with a stochiometric reactor. A bio-methane with 95% w/w in CH4 is obtained. The following responses are chosen: methane evolution rate (mmol/Lh), volumetric biomass production rate (C-mmol/Lh), produced bio-methane flow (kg/h), dilution rate (L/Lh). Experimental data are used for simulations in ChemCad 6.3® and results are used to investigate the effect of factors and to have a mathematical model for methane evolution rate through response surface methodology. Among the responses of factorial design, gassing rate has a positive effect on bio-methane flow, while reactor pressure has a positive effect on methane evolution rate. The greater stability of the process is obtained when the temperature of reactor and gassing rate are at lower and higher level respectively.