title: Anaerobic digestion of microalgal bacterial flocs from a raceway pond treating aquaculture wastewater: need for a biorefinery.
abstract: An outdoor raceway pond with microalgal bacterial flocs (MaB-flocs) is a novel sunlight-based system to treat pikeperch aquaculture wastewater while producing biomass. The harvested MaB-floc biomass (33tonTSha(-1)y(-1)) needs further valorization. Therefore, the biochemical methane yield (BMY) of MaB-floc biomass was determined in batch experiments. The results show significant differences between the BMY of MaB-flocs amongst their harvest dates (128-226NLCH4kg(-1)VS), a low anaerobic digestion conversion efficiency (25.0-36.2%), a moderate chlorophyll a removal (51.5-86.9%) and a low biogas profit (<0.01€m(-3)wastewater). None of the pretreatment methods screened (freezing, thermal, microwave, ultrasonic and chlorination, flue gas sparging, and acid) can be recommended due to a low BMY improvement and/or unfavorable energy balance. Therefore, anaerobic digestion of this MaB-floc biomass should only be granted a supporting role within a biorefinery concept.
authors.affiliation: Laboratory of Industrial Water and Ecotechnology (LIWET), Department of Industrial Biological Sciences, Ghent University, Graaf Karel de Goedelaan 5, B-8500 Kortrijk, Belgium. Electronic address: sofie.vandenhende@ugent.be.
authors.forename: Sofie
authors.initials: S
authors.lastname: Van Den Hende
authors.affiliation: Laboratory of Industrial Water and Ecotechnology (LIWET), Department of Industrial Biological Sciences, Ghent University, Graaf Karel de Goedelaan 5, B-8500 Kortrijk, Belgium.
authors.forename: Cedric
authors.initials: C
authors.lastname: Laurent
authors.affiliation: Laboratory of Industrial Water and Ecotechnology (LIWET), Department of Industrial Biological Sciences, Ghent University, Graaf Karel de Goedelaan 5, B-8500 Kortrijk, Belgium; Ecole des Métiers de l'Environnement (EME), Avenue Robert Schuman, F-35170 Bruz, France.
authors.forename: Marine
authors.initials: M
authors.lastname: Bégué
mesh_terms: D000693:Anaerobiosis; D017756:Aquaculture; D056804:Biofuels / Q000191:economics; D018533:Biomass; D019149:Bioreactors / Q000382:microbiology; D002734:Chlorophyll / Q000031:analogs & derivatives; D000077194:Chlorophyll A; D008697:Methane / Q000378:metabolism*; D058086:Microalgae / Q000378:metabolism*; D061005:Ponds / Q000382:microbiology; D012621:Seasons; D018505:Waste Management / Q000379:methods*; D062065:Wastewater / Q000382:microbiology*
chemical_list: D056804:Biofuels; D002734:Chlorophyll; D000077194:Chlorophyll A; D008697:Methane; D062065:Wastewater; C085815:chlorophyll a'
keywords: Algae; Biogas; MaB-floc; Pretreatment; Seasonal variability