Abstract
Aquatic micro-algae can be used as feedstocks for gaseous biofuel production via biological fermentation. However, micro-algae usually have low C/N ratios, which are not advantageous for fermentation. In this study, carbon-rich macro-algae (Laminaria digitata) mixed with nitrogen-rich micro-algae (Chlorella pyrenoidosa and Nannochloropsis oceanica) were used to maintain a suitable C/N ratio of 20 for a two-stage process combining hydrogen and methane fermentation. Co-fermentation of L. digitata and micro-algae facilitated hydrolysis and acidogenesis, resulting in hydrogen yields of 94.5-97.0 mL/gVS; these values were 15.5-18.5% higher than mono-fermentation using L. digitata. Through the second stage of methane co-fermentation, a large portion of energy remaining in the hydrogenogenic effluents was recovered in the form of biomethane. The two-stage batch co-fermentation markedly increased the energy conversion efficiencies (ECEs) from 4.6-6.6% during the hydrogen fermentation to 57.0-70.9% in the combined hydrogen and methane production.
Original language | English (US) |
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Pages (from-to) | 224-231 |
Number of pages | 8 |
Journal | Bioresource Technology |
Volume | 218 |
DOIs | |
State | Published - Oct 1 2016 |
Externally published | Yes |
Bibliographical note
Publisher Copyright:© 2016 Elsevier Ltd.
Keywords
- Co-fermentation
- Hydrogen
- Macro-algae
- Methane
- Micro-algae