Valorisation of macroalgae via the integration of hydrothermal carbonisation and anaerobic digestion

• Published in: Bioresource technology Vol. 312; p. 123539
• Main Authors: Brown, Aaron E., Finnerty, Gillian L., Camargo-Valero, Miller Alonso, Ross, Andrew B.
• Format: Journal Article
• Language: English
• Published: England Elsevier Ltd 01-09-2020
• Subjects: Anaerobic digestion; Hydrochar; Hydrothermal carbonisation; Macroalgae; Process waters; Hydrochar; Hydrothermal carbonisation; Anaerobic digestion; Process waters; Macroalgae
• ISSN: 0960-8524; 1873-2976
• DOI: 10.1016/j.biortech.2020.123539

•Different Integration strategies show significant differences in energy recovery.•Energy recovery is higher when hydrochar and process water are utilised separately.•Improvements in energy recovery are greater for F. serratus than S. latissima.
This study investigates the integration of hydrothermal carbonisation (HTC) with anaerobic digestion (AD) as a valorisation route for two macroalgae species; S. latissima (SL) and F. serratus (FS). HTC reactions were conducted at temperatures of 150 °C, 200 °C and 250 °C, with resulting hydrochars, process waters and hydrothermal slurries assessed for biomethane potential yields. Un-treated SL generated similar biomethane levels compared to all SL slurries. Whereas all FS slurries improved biomethane yields compared to un-treated FS. Hydrochars represent a greater energy carrier if used as a solid fuel, rather than a feedstock for anaerobic digestion. Integrating HTC and AD, through hydrochar combustion and process water digestion has a greater energetic output than anaerobic digestion of the un-treated macroalgae. Treatment at 150 °C, with separate utilisation of products, can improve the energetic output of S. latissima and F. serratus by 47% and 172% respectively, compared to digestion of the un-treated macroalgae.