초록
<P><B>Abstract</B></P> <P>Technological solutions to reduce greenhouse gas (GHG) emissions from anthropogenic sources are required. Heavy industrial processes, such as steel making, contribute considerably to GHG emissions. Fermentation of carbon monoxide (CO)-rich off gases with wild-type acetogenic bacteria can be used to produce ethanol, acetate, and 2,3-butanediol, thereby, reducing the carbon footprint of heavy industries. Here, the processes for the production of ethanol from CO-rich off gases are discussed and a perspective on further routes towards an integrated biorefinery at a steel mill is given. Recent achievements in genetic engineering as well as integration of other biotechnology platforms to increase the product portfolio are summarized. Already, yields have been increased and the portfolio of products broadened. To develop a commercially viable process, however, the extraction from dilute product streams is a critical step and alternatives to distillation are discussed. Finally, another critical step is waste(water) treatment with the possibility to recover resources.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Gas fermentation of CO-rich gas streams to ethanol is an almost mature technology. </LI> <LI> Addition of H<SUB>2</SUB> to the gas mixture can theoretically optimize the carbon balance. </LI> <LI> The product portfolio can be extended through genetic engineering. </LI> <LI> Integrating gas fermentation with other platforms generates value-added products. </LI> <LI> Extraction of dilute products will be a main challenge in the process. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>