title: Impacts of microalgae pre-treatments for improved anaerobic digestion: thermal treatment, thermal hydrolysis, ultrasound and enzymatic hydrolysis.
abstract: Anaerobic digestion (AD) of microalgae is primarily inhibited by the chemical composition of their cell walls containing biopolymers able to resist bacterial degradation. Adoption of pre-treatments such as thermal, thermal hydrolysis, ultrasound and enzymatic hydrolysis have the potential to remove these inhibitory compounds and enhance biogas yields by degrading the cell wall, and releasing the intracellular algogenic organic matter (AOM). This work investigated the effect of four pre-treatments on three microalgae species, and their impact on the quantity of soluble biomass released in the media and thus on the digestion process yields. The analysis of the composition of the soluble COD released and of the TEM images of the cells showed two main degradation actions associated with the processes: (1) cell wall damage with the release of intracellular AOM (thermal, thermal hydrolysis and ultrasound) and (2) degradation of the cell wall constituents with the release of intracellular AOM and the solubilisation of the cell wall biopolymers (enzymatic hydrolysis). As a result of this, enzymatic hydrolysis showed the greatest biogas yield increments (>270%) followed by thermal hydrolysis (60-100%) and ultrasounds (30-60%).
authors.affiliation: Cranfield University, Bedfordshire, UK.
authors.forename: Francesco
authors.initials: F
authors.lastname: Ometto
authors.affiliation: University of Oviedo, Oviedo, ES.
authors.forename: Gerardo
authors.initials: G
authors.lastname: Quiroga
authors.affiliation: Czech University of Life Sciences Prague, Prague, CZ.
authors.forename: Pavel
authors.initials: P
authors.lastname: Pšenička
authors.affiliation: Cranfield University, Bedfordshire, UK.
authors.forename: Rachel
authors.initials: R
authors.lastname: Whitton
authors.affiliation: Cranfield University, Bedfordshire, UK.
authors.forename: Bruce
authors.initials: B
authors.lastname: Jefferson
authors.affiliation: Cranfield University, Bedfordshire, UK. Electronic address: r.villa@cranfield.ac.uk.
authors.forename: Raffaella
authors.initials: R
authors.lastname: Villa
mesh_terms: D000693:Anaerobiosis; D056804:Biofuels; D018533:Biomass; D019149:Bioreactors / Q000382:microbiology*; D002473:Cell Wall / Q000378:metabolism*; D004798:Enzymes / Q000378:metabolism; D006358:Hot Temperature; D006868:Hydrolysis; D058086:Microalgae / Q000378:metabolism*; D000069453:Ultrasonic Waves
chemical_list: D056804:Biofuels; D004798:Enzymes
keywords: Anaerobic digestion; Cell wall degradation; Energy balance; Microalgae pre-treatment