title: Thermal pretreatment of algae for anaerobic digestion.
abstract: The objective of this work was to determine the benefit of thermal pretreatment on biogas yield from microalgae-fed anaerobic digester mesocosms. Replicate Nanochloropsis oculata cultures were heated for 4h at 30, 60, and 90°C, as well as at a constant temperature of 90°C for 1, 3.5, and 12h. Net biogas production increased from 0.28L biogas/g volatile solids added (VSa) for the control to 0.39 L biogas/g VSa (p<0.01) when heated at 90°C, but there was no improvement at 30 or 60°C. Increased biogas production correlated with increased soluble chemical oxygen demand (COD). Net biogas production increased as a function of heating time, from 0.32 L biogas/g VSa for the control, to 0.41, 0.43, and 0.44 L biogas/g VSa (p<0.05 for all combinations vs. control) when preheated at 90°C for 1, 3.5, and 12h, respectively. However, despite enhanced biogas production the energy balance is negative for thermal pretreatment.
authors.affiliation: Department of Civil and Environmental Engineering, Seattle University, 901 12th Ave., Seattle, WA 98122, United States. Electronic address: marsolem@seattleu.edu.
authors.forename: Michael D
authors.initials: MD
authors.lastname: Marsolek
authors.forename: Elizabeth
authors.initials: E
authors.lastname: Kendall
authors.forename: Phillip L
authors.initials: PL
authors.lastname: Thompson
authors.forename: Teodora Rutar
authors.initials: TR
authors.lastname: Shuman
mesh_terms: D000693:Anaerobiosis; D056804:Biofuels; D057919:Biological Oxygen Demand Analysis; D001709:Biotechnology / Q000379:methods*; D008697:Methane / Q000032:analysis; D058086:Microalgae / Q000378:metabolism*; D013696:Temperature; D013997:Time Factors; D014835:Volatilization
chemical_list: D056804:Biofuels; D008697:Methane
keywords: Algae; Anaerobic digestion; Biofuel; Biogas; Pretreatment