초록
<P><B>Abstract</B></P><P>In this study, a new outer-cycle flat-panel photobioreactor was designed for an anaerobic, photo-fermentation process by <I>Rhodobacter sphaeroides</I> ZX-5. In order to obtain the high hydrogen yield, photo-hydrogen production by fed-batch culture with on-line oxidation–reduction potential (ORP) feedback control was investigated. Meanwhile, the effects of feeding malic acid concentration and pH adjustment on the growth and hydrogen production of <I>R</I>. <I>sphaeroides</I> ZX-5 were studied. In the entire fed-batch culture, biomass (i.e., OD<SUB>660</SUB>) rapidly increased up to 1.79 within 18 h, and then OD<SUB>660</SUB> value stayed constant within a range of 1.85–2.18 until the end of the photo-fermentation. The cumulative hydrogen volumes in each phase of fed-batch process were 2339, 1439, 1328, and 510 ml H<SUB>2</SUB>/l-culture, respectively. Throughout the entire repeated fed-batch photo-fermentation, the maximum substrate conversion efficiency of 73.03% was observed in the first fed-batch process, obviously higher than that obtained from batch culture process (59.81%). In addition, compared to the batch culture, a much higher maximum hydrogen production rate (102.33 ml H<SUB>2</SUB>/l h) was achieved during fed-batch culture. The results demonstrated that photo-hydrogen production using fed-batch operation based on ORP feedback control is a favorable choice of sustainable and feasible strategy to improve phototrophic hydrogen production efficiency.</P> <P><B>Highlights</B></P><P>► The fed-batch culture mode based on ORP level has proved to be capable of attaining high-rate and high-yield phototrophic H<SUB>2</SUB> production. ► The feeding time controlled by computer is conducive to future large-scale photo-hydrogen production. ► A new outer-cycle flat-panel photobioreactor was designed for an anaerobic, photo-fermentation process.</P>