title: Co-generation of biohydrogen and biomethane through two-stage batch co-fermentation of macro- and micro-algal biomass.
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 94.5-97.0mL/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.
authors.affiliation: State Key Laboratory of Clean Energy Utilization, Zhejiang University, Hangzhou 310027, China; MaREI Centre, Environmental Research Institute, University College Cork, Cork, Ireland.
authors.forename: Lingkan
authors.initials: L
authors.lastname: Ding
authors.affiliation: State Key Laboratory of Clean Energy Utilization, Zhejiang University, Hangzhou 310027, China. Electronic address: juncheng@zju.edu.cn.
authors.forename: Jun
authors.initials: J
authors.lastname: Cheng
authors.affiliation: Key Laboratory of Low-grade Energy Utilization Technologies and Systems, Chongqing University, Chongqing 400044, China.
authors.forename: Ao
authors.initials: A
authors.lastname: Xia
authors.affiliation: MaREI Centre, Environmental Research Institute, University College Cork, Cork, Ireland.
authors.forename: Amita
authors.initials: A
authors.lastname: Jacob
authors.affiliation: MaREI Centre, Environmental Research Institute, University College Cork, Cork, Ireland.
authors.forename: Markus
authors.initials: M
authors.lastname: Voelklein
authors.affiliation: MaREI Centre, Environmental Research Institute, University College Cork, Cork, Ireland; School of Engineering, University College Cork, Cork, Ireland.
authors.forename: Jerry D
authors.initials: JD
authors.lastname: Murphy
mesh_terms: D056804:Biofuels; D018533:Biomass; D019149:Bioreactors; D002244:Carbon / Q000032:analysis / Q000737:chemistry / Q000378:metabolism; D002708:Chlorella / Q000382:microbiology; D003246:Conservation of Energy Resources; D005285:Fermentation; D006859:Hydrogen / Q000032:analysis / Q000737:chemistry / Q000378:metabolism*; D007795:Laminaria / Q000378:metabolism; D008697:Methane / Q000032:analysis / Q000737:chemistry / Q000378:metabolism*; D058086:Microalgae / Q000378:metabolism*; D009584:Nitrogen / Q000032:analysis / Q000737:chemistry / Q000378:metabolism; D059205:Renewable Energy
chemical_list: D056804:Biofuels; D002244:Carbon; D006859:Hydrogen; D009584:Nitrogen; D008697:Methane
keywords: Co-fermentation; Hydrogen; Macro-algae; Methane; Micro-algae