The role of acid incubation in rapid immobilization of hydrogen-producing culture in anaerobic upflow column reactors
Resource
International Journal of Hydrogen Energy 33 (19): 5151-5160
Journal
International Journal of Hydrogen Energy
Journal Volume
33
Journal Issue
19
Pages
5151-5160
Date Issued
2008
Date
2008
Author(s)
Abstract
An approach of acidification was examined on formation of hydrogen-producing granules and biofilms in upflow column-shaped reactors. The reactors were fed with synthetic glucose wastewater and operated at 37 °C and pH 5.5. The acclimated anaerobic culture was inoculated in four reactors designated R1, R2, R3 and R4, with R3 and R4 filled with granular activated carbon as support medium. To unveil the roles of acidification, microbial culture in R2 and R3 was subject to an acid incubation for 24 h by shifting the culture pH from 5.5 to 2.0. The experimental results suggested that the acidification substantially accelerated microbial granulation, but not biofilm formation. Microbial activities were inhibited by the acid incubation for about 78 h, resulting in the retarded formation of biofilms of the acidified culture. Reducing culture pH resulted in improvement in cell surface physicochemical properties favoring microbial adhesion and immobilization. Zeta potential increased from -25.3 mV to 11.9 mV, hydrophobicity in terms of contact angle improved from 31° to 38° and production of extracellular polymers increased from 66 mg/g-VSS to 136 mg/g-VSS. As a result of the formation of granules and biofilms, high hydrogen production rates of 6.98 and 7.49 L/L h were achieved in granule-based and biofilm-based reactors, respectively. It is concluded that acid incubation is an efficient means to initiate the rapid formation of granules by regulating the surface characteristics of microbial culture. The use of support media as starting nuclei may result in rapid formation of biofilms without the acidification. © 2008 International Association for Hydrogen Energy.
Subjects
Biofilm formation; Cell surface physicochemical characteristics; Granulation; Hydrogen production; Upflow Column-shaped reactor
Other Subjects
Activated carbon; Biofilms; Biofilters; Cell culture; Cell immobilization; Cell membranes; Chemical reactions; Columns (structural); Contact angle; Gas fuel manufacture; Glucose; Granulation; Hydrogen; Nonmetals; Photoresists; Spectrum analyzers; Wastewater; Zeta potential; Biofilm formation; Biofilm formations; Cell surface physicochemical characteristics; Column reactors; Contact angles; Extra-cellular polymers; Granular activated carbons; In-cell; Microbial activities; Microbial adhesion; Microbial cultures; Physico-chemical properties; Production rates; Rapid formation; Support media; Surface characteristics; Upflow Column-shaped reactor; Zeta potentials; Hydrogen production
Type
journal article
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