Previously published results reported a low specific methane potential (SMP) of Sargassum ssp. ranging from 120 to 190 mL CH4/gVSS ( Bird et al., 1990 and Chynoweth et al., 2001) while Jard et al. (2013) found the lowest methane potential (130 mL CH4/gVS) for S. muticum among ten macroalgae studied. Low carbohydrates content, high content of insoluble fibers (which are difficult to degrade) and high levels of polyphenols (which are potential inhibitors in CHIR265 digestion) were cited as the main reasons for low methane yield from Sargassum biomass. Available studies are scarce, and methane yields were usually obtained from batch assays, which could not discern inhibition situations ( Jard et al., 2013).
The objectives of the present work were (i) to obtain the specific methane potential for three samples of S. muticum collected from the Galician coast (Northwest Spain) at different seasons, (ii) to identify the conditions for absence of process inhibition, and (iii) to assess the operation conditions of continuous digesters treating S. muticum biomass. For Gaia purposes, batch and semi-continuous assays at different alga concentrations and organic loading rates were used.