초록
<P><B>Abstract</B></P> <P>This study investigated the acetate production from gas mixture of hydrogen (H<SUB>2</SUB>) and carbon dioxide (CO<SUB>2</SUB>) in the ratio of 7:3 using two acetogens: <I>Acetobacterium woodii</I> and <I>Clostridium ljungdahlii</I>. Batch result shows <I>A. woodii</I> performed two-phase degradation with the presence of glucose that lactate was produced from glucose and was reutilized for the production of butyrate and few acetate, while only acetate was detected when providing gas mixture. <I>C. ljungdahlii</I> produced butyrate and ethanol along with acetate when glucose was introduced, while only ethanol and acetate were found by feeding gas mixture. The acetate-to-ethanol (A/E) ratio can be enhanced by cell immobilization, while GAC immobilization produced only acetate and the production rate reached 0.072 mmol/d under fed-batch operation. Acetate production rate increased from 18 to 28 mmol/L/d with GAC immobilization when gas flowrate increased from 100 to 300 mL/min in anaerobic fluidized membrane bioreactor (AFMBR), and a highest A/E ratio of 30 implies the possible application of acetate recovery from H<SUB>2</SUB> and CO<SUB>2</SUB>.</P> <P><B>Highlights</B></P> <P> <UL> <LI> <I>Clostridium ljungdahlii</I> with GAC immobilization can produce acetate over ethanol. </LI> <LI> A high acetate-to-ethanol ratio of 30 was achieved by <I>Clostridium ljungdahlii</I>. </LI> <LI> This study reveals the potential to recover acetate from H<SUB>2</SUB>/CO<SUB>2</SUB>-containing off-gas. </LI> </UL> </P>