Biogas production using anaerobic groundwater containing a subterranean microbial community associated with the accretionary prism.

Kyohei Baito,Satomi Imai,Yu Sato,Hiroyuki Kimura,Makoto Matsushita,Miku Otani

doi:10.1111/1751-7915.12179

Abstract

In a deep aquifer associated with an accretionary prism, significant methane (CH4) is produced by a subterranean microbial community. Here, we developed bioreactors for producing CH4 and hydrogen (H2) using anaerobic groundwater collected from the deep aquifer. To generate CH4, the anaerobic groundwater amended with organic substrates was incubated in the bioreactor. At first, H2 was detected and accumulated in the gas phase of the bioreactor. After the H2 decreased, rapid CH4 production was observed. Phylogenetic analysis targeting 16S rRNA genes revealed that the H2-producing fermentative bacterium and hydrogenotrophic methanogen were predominant in the reactor. The results suggested that syntrophic biodegradation of organic substrates by the H2-producing fermentative bacterium and the hydrogenotrophic methanogen contributed to the CH4 production. For H2 production, the anaerobic groundwater, amended with organic substrates and an inhibitor of methanogens (2-bromoethanesulfonate), was incubated in a bioreactor. After incubation for 24 h, H2 was detected from the gas phase of the bioreactor and accumulated. Bacterial 16S rRNA gene analysis suggested the dominance of the H2-producing fermentative bacterium in the reactor. Our study demonstrated a simple and rapid CH4 and H2 production utilizing anaerobic groundwater containing an active subterranean microbial community.

Highlights

SummaryIn a deep aquifer associated with an accretionary prism, significant methane (CH4) is produced by a subterranean microbial community
Accretionary prisms are distributed over the convergent plate boundary, where oceanic and continental crusts collide, and found in large regions of the world, e.g. Japan, Taiwan, Indonesia, Peru, Chile and New Zealand, and Alaska and Washington in the United States (Kano et al, 1991; Davis et al, 1998; Fagereng, 2011; Hervé et al, 2013)
The findings may be used for the development of a novel bioenergy production system that combines the bioreactors for CH4 and H2 production and a ‘natural subterranean methane reactor’ in a deep aquifer associated with an accretionary prism

Summary

In a deep aquifer associated with an accretionary prism, significant methane (CH4) is produced by a subterranean microbial community. We developed bioreactors for producing CH4 and hydrogen (H2) using anaerobic groundwater collected from the deep aquifer. To generate CH4, the anaerobic groundwater amended with organic substrates was incubated in the bioreactor. Phylogenetic analysis targeting 16S rRNA genes revealed that the H2-producing fermentative bacterium and hydrogenotrophic methanogen were predominant in the reactor. The results suggested that syntrophic biodegradation of organic substrates by the H2-producing fermentative bacterium and the hydrogenotrophic methanogen contributed to the CH4 production. For H2 production, the anaerobic groundwater, amended with organic substrates and an inhibitor of methanogens (2-bromoethanesulfonate), was incubated in a bioreactor. After incubation for 24 h, H2 was detected from the gas phase of the bioreactor and accumulated. Our study demonstrated a simple and rapid CH4 and H2 production utilizing anaerobic groundwater containing an active subterranean microbial community.

Introduction

Results and discussion

Experimental procedures

Conclusions