초록
<P><B>Abstract</B></P> <P>The main objective of the study is to investigate the effect of hydraulic retention times on continuous dark fermentative biohydrogen production in an up-flow packed bed reactor (UPBR) containing a novel microorganism immobilization material namely polyester fiber beads. The hydrogen producing dark fermentative microorganisms were obtained by heat-pretreatment of anaerobic sludge from the acidogenic phase of an anaerobic wastewater treatment plant. Glucose was the sole carbon source and the initial concentration was 15 ± 1 g/L throughout the continuous feeding. UPBR was operated under the thermophilic condition at T = 48 ± 2 °C and at varying HRTs between 2 h and 6 h. The hydrogen productivity of continuously operated UPBR increased with increasing HRT. Hydrogen production volume varied between 4331 and 6624 ml/d, volumetric hydrogen production rates (VHPR) were obtained as 3.09–4.73 L H<SUB>2</SUB>/L day, and hydrogen production yields (HY) were 0.49 mol/mol glucose-0.89 mol/mol glucose depending on HRT. Maximum daily hydrogen volume (6624 ml/d), the yield (0.89 mol/mol glucose) and VHPR (4.73 L H<SUB>2</SUB>/L day) were obtained at HRT = 6 h. The production rate and the yield decreased with increasing organic loading rate due to substrate inhibition.</P> <P><B>Highlights</B></P> <P> <UL> <LI> UPBR was operated continuously at HRTs between 2 h and 6 h. </LI> <LI> Polyester fiber beads were used for immobilization of heat pretreated sludge. </LI> <LI> Maximum H<SUB>2</SUB> yield of 0.89 mol/mol glucose was attained at HRT = 6 h. </LI> <LI> Maximum volumetric H<SUB>2</SUB> production rate of 4.73 L H<SUB>2</SUB>/L day was obtained at HRT = 6 h. </LI> <LI> H<SUB>2</SUB> content was stable around 60% at all HRT. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>