The present study proposes a novel alternative method of the current biogas upgrading techniques by converting CO2 (in the biogas)into valuable chemicals (e.g., volatile fatty acids)using H2 as energy source and acetogenic mixed culture as biocatalyst. The influence of thermal treatment (90 °C)on the inhibition of the methanogenic archaea and enriching the acetogenic bacteria in different inocula (mesophilic and thermophilic)was initially tested. The most efficient inoculum that achieved the highest performance through the fermentation process was further used to define the optimum H2/CO2 gas ratio that secures maximum production yield of chemicals and maximum biogas upgrading efficiency. In addition, 16S rRNA analysis of the microbial community was conducted at the end of the experimental period to target functional microbes. The maximum biogas content (77% (v/v))and acetate yield (72%)were achieved for 2H2:1CO2 ratio (v/v), with Moorella sp. 4 as the most dominant thermophilic acetogenic bacterium.
Bibliographical noteFunding Information:
Hector Garcia was thankful for technical support. Novo Nordisk Foundation (NNF16OC0021568) and Danish Council for Independent Research (DFF-1335-00142) had been corroborative financially this research. The Ministry of Higher Education of Egypt is gratefully acknowledged for PhD channel mission to the first author. The authors are grateful to Dr. Panagiotis Kougias and Dr. Laura Treu for helping in microbiological data analysis.
© 2019 Elsevier Ltd
- Acetyl-CoA pathway
- Biogas upgrading
- Gas fermentation
- Microbial community