Assessment of continuous fermentative hydrogen and methane co-production using macro- and micro-algae with increasing organic loading rate

Lingkan Ding, Enrique Chan Gutierrez, Jun Cheng, Ao Xia, Richard O'Shea, Amita Jacob Guneratnam and Jerry D. Murphy

Energy, 2018, vol. 151, issue C, 760-770

Abstract: A two-stage continuous fermentative hydrogen and methane co-production using macro-algae (Laminaria digitata) and micro-algae (Arthrospira platensis) at a C/N ratio of 20 was established. The hydraulic retention time (HRT) of first-stage H2 reactor was 4 days. The highest specific hydrogen yield of 55.3 mL/g volatile solids (VS) was obtained at an organic loading rate (OLR) of 6.0 gVS/L/d. In the second-stage CH4 reactor at a short HRT of 12 days, a specific methane yield of 245.0 mL/gVS was achieved at a corresponding OLR of 2.0 gVS/L/d. At these loading rates, the two-stage continuous system offered process stability and effected an energy yield of 9.4 kJ/gVS, equivalent to 77.7% of that in an idealised batch system. However, further increases in OLR led to reduced hydrogen and methane yields in both reactors. The process was compared to a one-stage anaerobic co-digestion of algal mixtures at an HRT of 16 days. A remarkably high salinity level of 13.3 g/kg was recorded and volatile fatty acid accumulations were encountered in the one-stage CH4 reactor. The two-stage system offered better performances in both energy return and process stability. The gross energy potential of the advanced gaseous biofuels from this algal mixture may reach 213 GJ/ha/yr.

Keywords: Macro-algae; Micro-algae; Two-stage co-fermentation; Hydrogen; Methane (search for similar items in EconPapers)
Date: 2018
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Citations: View citations in EconPapers (8)

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Persistent link: https://EconPapers.repec.org/RePEc:eee:energy:v:151:y:2018:i:c:p:760-770

DOI: 10.1016/j.energy.2018.03.103

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