title: The use of microalgae and their culture medium for biogas production in an integrated cycle.
abstract: Vinasse is a residue produced in large quantities as a sub-product of ethanol production. Anaerobic digestion of vinasse can yield large amounts of biogas, but often difficulties arise in maintaining stable operation, due to the acidity of the material (which has a pH between 3.5 and 5) and a strong tendency to further acidification. Anaerobically digested vinasse can be used as part of a culture medium for microalgae cultivation, for the production of biodiesel and other compounds, whilst the excess CO2 produced in the ethanol fermentation can be used to stimulate algal growth. During algae cultivation, the pH of the culture medium has a strong tendency to increase; therefore, recycling of the spent culture medium or the concentrated algae suspension to the anaerobic digester treating vinasse was considered an option for pH stabilization there. Batch tests, however, showed that alkalinity of the spent culture broth, in spite of its high pH, is too low (only 350 mgCaCO3L(-1)) to help stabilise the pH of vinasse digestion. Alkalinity of the algae suspension is higher and digestion of a mixture of vinasse and a suspension of algae results in efficient biogas production, but still the alkalinity is insufficient to stabilise the pH in a range suitable for methanogenic microorganisms; hence, the addition of additional alkalinity, for instance as sodium bicarbonate or urea, remains necessary.
authors.affiliation: Federal University of Mato Grosso do Sul (UFMS), Centre of Exact Sciences and Technology (CCET), P.O. Box 549, 79070-900 Campo Grande-MS, Brazil E-mail: marc.boncz@ufms.br.
authors.forename: E L
authors.initials: EL
authors.lastname: Formagini
authors.affiliation: Federal University of Mato Grosso do Sul (UFMS), Centre of Exact Sciences and Technology (CCET), P.O. Box 549, 79070-900 Campo Grande-MS, Brazil E-mail: marc.boncz@ufms.br.
authors.forename: F R
authors.initials: FR
authors.lastname: Marques
authors.affiliation: Federal University of Mato Grosso do Sul (UFMS), Centre of Exact Sciences and Technology (CCET), P.O. Box 549, 79070-900 Campo Grande-MS, Brazil E-mail: marc.boncz@ufms.br.
authors.forename: M L
authors.initials: ML
authors.lastname: Serejo
authors.affiliation: Federal University of Mato Grosso do Sul (UFMS), Centre of Exact Sciences and Technology (CCET), P.O. Box 549, 79070-900 Campo Grande-MS, Brazil E-mail: marc.boncz@ufms.br.
authors.forename: P L
authors.initials: PL
authors.lastname: Paulo
authors.affiliation: Federal University of Mato Grosso do Sul (UFMS), Centre of Exact Sciences and Technology (CCET), P.O. Box 549, 79070-900 Campo Grande-MS, Brazil E-mail: marc.boncz@ufms.br.
authors.forename: M A
authors.initials: MA
authors.lastname: Boncz
mesh_terms: D000693:Anaerobiosis; D056804:Biofuels; D003470:Culture Media; D006863:Hydrogen-Ion Concentration; D007220:Industrial Waste; D058086:Microalgae; D031786:Saccharum
chemical_list: D056804:Biofuels; D003470:Culture Media; D007220:Industrial Waste