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Semi-continuous anaerobic digestion of the marine micro-algal species I. galbana and D. salina grown under low and high sulphate conditions

Semi-continuous anaerobic digestion of the marine micro-algal species I. galbana and D. salina grown under low and high sulphate conditions
Semi-continuous anaerobic digestion of the marine micro-algal species I. galbana and D. salina grown under low and high sulphate conditions

Anaerobic digestion of marine micro-algae is a necessary step for their incorporation into the future portfolio of biofuels. Digestion of marine feedstocks can pose operational issues associated with competition and toxicity to the microbial consortium. This research examined the marine species Isochrysis galbana and Dunaliella salina continuously cultivated in a tubular photobioreactor using a low sulphate medium; D. salina was also cultivated with a high sulphate medium (4.7 g SO4 L−1). Harvested micro-algal biomass was used as feedstock in semi-continuous digestion with a salt-adapted inoculum. Stable operation was achieved with reasonable specific methane production (SMP)despite a short (15-day)retention time. SMP for I. galbana and D. salina was 0.244 and 0.233 L CH4 g−1 volatile solids (VS), with VS destruction 32% and 48% respectively. SMP ranged from 62 to 94% of the biochemical methane potential, but was only 32–49% of theoretical methane yields, indicating pre-treatments may be beneficial. Changing from low to high sulphate D. salina reduced the SMP to 0.193 L CH4 g−1 VS with a rise in H2S production. Under semi-continuous digestion, evidence for sulphide precipitation and oxidation was observed, which were not seen in batch analyses. This highlights the importance of conducting continuous rather than batch studies, to avoid overlooking these effects.

Adaption, Biogas, Hydrogen sulphide, Inhibition, Marine micro-algae, Semi-continuous anaerobic digestion
2211-9264
1-12
Roberts, Keiron P.
da377993-082e-4693-8814-8983ab028258
Heaven, Sonia
f25f74b6-97bd-4a18-b33b-a63084718571
Banks, Charles J.
5c6c8c4b-5b25-4e37-9058-50fa8d2e926f
Roberts, Keiron P.
da377993-082e-4693-8814-8983ab028258
Heaven, Sonia
f25f74b6-97bd-4a18-b33b-a63084718571
Banks, Charles J.
5c6c8c4b-5b25-4e37-9058-50fa8d2e926f

Roberts, Keiron P., Heaven, Sonia and Banks, Charles J. (2019) Semi-continuous anaerobic digestion of the marine micro-algal species I. galbana and D. salina grown under low and high sulphate conditions. Algal Research, 41, 1-12, [101564]. (doi:10.1016/j.algal.2019.101564).

Record type: Article

Abstract

Anaerobic digestion of marine micro-algae is a necessary step for their incorporation into the future portfolio of biofuels. Digestion of marine feedstocks can pose operational issues associated with competition and toxicity to the microbial consortium. This research examined the marine species Isochrysis galbana and Dunaliella salina continuously cultivated in a tubular photobioreactor using a low sulphate medium; D. salina was also cultivated with a high sulphate medium (4.7 g SO4 L−1). Harvested micro-algal biomass was used as feedstock in semi-continuous digestion with a salt-adapted inoculum. Stable operation was achieved with reasonable specific methane production (SMP)despite a short (15-day)retention time. SMP for I. galbana and D. salina was 0.244 and 0.233 L CH4 g−1 volatile solids (VS), with VS destruction 32% and 48% respectively. SMP ranged from 62 to 94% of the biochemical methane potential, but was only 32–49% of theoretical methane yields, indicating pre-treatments may be beneficial. Changing from low to high sulphate D. salina reduced the SMP to 0.193 L CH4 g−1 VS with a rise in H2S production. Under semi-continuous digestion, evidence for sulphide precipitation and oxidation was observed, which were not seen in batch analyses. This highlights the importance of conducting continuous rather than batch studies, to avoid overlooking these effects.

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More information

Accepted/In Press date: 24 May 2019
e-pub ahead of print date: 31 May 2019
Published date: 1 August 2019
Keywords: Adaption, Biogas, Hydrogen sulphide, Inhibition, Marine micro-algae, Semi-continuous anaerobic digestion

Identifiers

Local EPrints ID: 434189
URI: http://eprints.soton.ac.uk/id/eprint/434189
ISSN: 2211-9264
PURE UUID: 76296fa0-2c0b-46e0-b676-bcd6900bb3c8
ORCID for Sonia Heaven: ORCID iD orcid.org/0000-0001-7798-4683

Catalogue record

Date deposited: 13 Sep 2019 16:30
Last modified: 07 Oct 2020 01:37

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