A comprehensive evaluation of digestate gasification in biogas atmospheres towards the integration of anaerobic digestion and gasification.

The rational disposal of digestate is a prerequisite for the sustainable development of anaerobic digestion. This study evaluated the feasibility of digestate gasification with a biogas atmosphere to achieve the integration of anaerobic digestion and gasification. Besides, four atmospheres (N2, CO2, CH4 and biogas) were used to explore the effect of biogas atmosphere on digestate gasification performance. The results showed that a CO2 atmosphere could enhance the conversion efficiency of digestate through the Boudouard reaction, while a CH4 atmosphere was conducive to the generation of H2 through the reforming and cracking reactions. Moreover, the CO2 and CH4 in the biogas atmosphere exhibited significant promotional effects during gasification. The syngas yield of digestate gasification in the biogas atmosphere was 1.91 Nm3/kg, and the actual H2 + CO yield was 0.38 Nm3/kg, which was 131% higher than the theoretical value. This study provides a potential approach for the efficient disposal of digestate, and the concept of biorefinery is further strengthened through this innovative integration of anaerobic digestion and gasification.