Suppression of methanogenic activity in anaerobic granular biomass for hydrogen production

Abstract

BACKGROUND: Several pretreatment methods at lab-scale have been developed to inactivate methane-producing and hydrogen-consuming microorganisms. The need to obtain a hydrogen-producing inoculum by a more practical method is still necessary. The objective of this study was to evaluate the adaptation of anaerobic granules to suppress the methanogenic activity for hydrogen production.RESULTS: Preliminary tests in discontinuous operation indicated that methanogenic bacteria were hardly suppressed. The continuous adaptation of the granules, at pH of 4.5 and HRT of 5.5 h, produced hydrogen and successfully suppressed the methanogenic activity. An even distribution of β-polysaccharides and cells was observed when the adapted granules were stained with fluorescent molecular tags. The reactor productivity was 71 ± 6 mL-H 2 L reactor −1 h −1 with a yield of 2.6 ± 0.2 mol H 2 mol -1 glucose. CONCLUSION: Hydrogen was produced from methanogenic granules. The continuous strategy successfully suppressed the methanogenic activity of the seeded granules and the hydrogen production was stable. The high yield and even distribution of cells suggests that the continuous adaptation generated a more active biomass due to an improved mass transfer present in the process.

Review on the start-up experiences of continuous fermentative hydrogen producing bioreactors

“…However, start-up period of granular systems for biohydrogen generation could be considerably shortened through the transformation of methanogenic granules (obtained e.g. from already existing and well-established anaerobic, methane forming UASB reactors) into hydrogen producing ones, as recently reported [54].…”

“…Alternatively to the strategy described in [54], it has been reported that the start-up time of UASBR could also be significantly decreased by thriving H 2 -producing cells in CSTR arrangement prior to transferring them to the up-flow anaerobic sludge blanket reactor as seeding source [59]. As it was found, despite the high shearing forces in CSTR, self-flocculation of hydrogengenerating bacteria was notably faster than in UASBR and explained by the more intense mass transfer capacity of the former reactor type.…”

Uncoupled hydrogen and volatile fatty acids generation in a two-step biotechnological anaerobic process fed with actual site wastewater

“…Reduction of HRTs typically prevents processes which occur at a later stage, such as acetogenesis and methanogenesis [23]. In particular, full suppression of methanogenesis has been observed in granular biomass [24], that is, in a system where biomass retention is significantly higher than with the biofilm reactors adopted in this study. The concept of a two-phase anaerobic digestion system is not new, though it was initially proposed [25] and then later widely applied (reviewed in [26]) to separate hydrolytic/acidogenic activity from acetogenic/methanogenic activity.…”

Biohydrogen production from winery effluents: control of the homoacetogenesis through the headspace gas recirculation

“…Though, CSTRs are energy‐demanding systems and have the problem of biomass washout when are operated at high organic loads such as the presenting real effluents such as WW . Thus, granular biomass systems such as the upflow anaerobic sludge blanket (UASB) reactors characterized by the retentions of the biomass are particularly suitable for hydrogen production from wastewater with high organic matter content …”