Sargassum biorefineries: potential opportunities towards shifting from wastes to products

Sargassum tides on the coasts of the Mexican Caribbean have become an ecological and socioeconomic problem that requires a comprehensive solution. In this study, compositional analyses of Sargassum consortium (SC) showed 24.61% of carbohydrates, which could be used in alginate, fucoidan, and biofuel production. Also, 3.14 mg of p-Coumaric acid/g of SC was identified by high-performance liquid chromatography (HPLC). This compound is a precursor to the monolignols involved in the synthesis of lignin. Moreover, gallic and vanillic acid were found in concentrations of 2.90 and 3.37 mg of compound/g of SC. HPLC and infrared spectra analysis confirmed the presence of lignin in the SC. In order to propose potential biorefinery applications, an alginate extraction process was developed and evaluated; results indicated that alginate has lower metal content than the original biomass. A reduction in six metals was achieved, including arsenic, to below the detection limit, and the decrease of 95.4% of zinc and 75.3% of aluminum. Furthermore, the characterization of the solid waste from the alginate extraction showed an increased in glucose, xylose, and fucose proportion, when compared with the initial biomass. In addition, carbon-nitrogen maintained an optimal ratio of 20.35 to be used for biofuel production and value-added compounds, allowing the development of a biorefinery system involving zero waste from SC, which would help to reduce negative environmental and socioeconomic impacts.