Fermentative hydrogen production and bacterial community structure in high-rate anaerobic bioreactors containing silicone-immobilized and self-flocculated sludge
✍ Scribed by Shu-Yii Wu; Chun-Hsiung Hung; Chi-Neng Lin; Hsin-Wei Chen; An-Sheng Lee; Jo-Shu Chang
- Book ID
- 102762731
- Publisher
- John Wiley and Sons
- Year
- 2006
- Tongue
- English
- Weight
- 519 KB
- Volume
- 93
- Category
- Article
- ISSN
- 0006-3592
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✦ Synopsis
Abstract
A novel continuously stirred anaerobic bioreactor (CSABR) seeded with silicone‐immobilized sludge was developed for high‐rate fermentative H~2~ production using sucrose as the limiting substrate. The CSABR system was operated at a hydraulic retention time (HRT) of 0.5–6 h and an influent sucrose concentration of 10–40 g COD/L. With a high feeding sucrose concentration (i.e., 30–40 g COD/L) and a short HRT (0.5 h), the CSABR reactor produced H~2~ more efficiently with the highest volumetric rate (${\nu}_{{\rm H}_2}$) of 15 L/h/L (i.e., 14.7 mol/d/L) and an optimal yield of ca. 3.5 mol H~2~/mol sucrose. The maximum ${\nu}_{{\rm H}_2}$ value obtained from this work is much higher than any other ${\nu}_{{\rm H}_2}$ values ever documented. Formation of self‐flocculated granular sludge occurred during operation at a short HRT. The granule formation is thought to play a pivotal role in the dramatic enhancement of H~2~ production rate, because it led to more efficient biomass retention. A high biomass concentration of up to 35.4 g VSS/L was achieved even though the reactor was operated at an extremely low HRT (i.e., 0.5 h). In addition to gaining high biomass concentrations, formation of granular sludge also triggered a transition in bacterial community structure, resulting in a nearly twofold increase in the specific H~2~ production rate. According to denatured‐gradient‐gel‐electrophoresis analysis, operations at a progressively decreasing HRT resulted in a decrease in bacterial population diversity. The culture with the best H~2~ production performance (at HRT = 0.5 h and sucrose concentration = 30 g COD/L) was eventually dominated by a presumably excellent H~2~‐producing bacterial species identified as Clostridium pasteurianum. © 2005 Wiley Periodicals, Inc.