Hydrothermal conversion of water lettuce biomass at 473 or 523Â K

► A new hydrothermal treatment technology for aquatic biomass was proposed. ► Fresh aquatic biomass was decomposed hydrothermally without the need for adding external water. ► Solid residue and liquid product contains many value-added materials after hydrothermal treatment. ► Adding sodium carbonate seems less effect on the hydrothermal conversion of aquatic biomass.