NOVELTY - Phosphorus-containing biomass is hydrothermally processed in the presence of a non-metallic type catalyst. The obtained slurry of biomass containing the catalyst is heated, preheated, and hydrothermally treated. The ash content produced by hydrothermal treatment is reacted with hydrochloric acid, and hydrochloric acid is filtered. The filtrate is reacted with sodium-hydroxide aqueous solution, and the deposits are recovered. The slurry of biomass adhered is peeled from the inner surface.    USE - Recovery of phosphate from biomass. Uses include but are not limited to livestock excrement, organic refuse, foodstuffs waste material, and sewage sludge.    ADVANTAGE - The method enables efficient and economical gasification of biomass, production of fuel gas, such as methane and hydrogen, and recovery of phosphates. Energy is efficiently exploited from biomass containing phosphorus. Hydroxyapatite obtained as deposit can be suitably used for artificial bones and dental fillers.    DETAILED DESCRIPTION - Phosphorus-containing biomass is hydrothermally processed in the presence of a non-metallic type catalyst at 100-250 degrees C and 0.1-4 MPa. The obtained slurry of biomass containing the catalyst is introduced into a heater and heated. The heated slurry is introduced into a preheater, preheated, introduced into a reactor, and then hydrothermally treated at 374 degrees C or more and 22.1 MPa or more. The ash content produced by hydrothermal treatment is reacted with hydrochloric acid, and hydrochloric acid is filtered after reaction. The obtained filtrate is reacted with sodium-hydroxide aqueous solution, and the produced deposits are recovered. The slurry of biomass adhered is peeled from the inner surface by providing an impact to the inner surface of piping which connects the heater, pre-heater, and reactor, or the reactor. Phosphates are recovered from the reaction material after processing. An INDEPENDENT CLAIM is included for phosphate recovery system consisting of a preprocessor for hydrothermal processing of biomass, a reactor for hydrothermally treating the biomass slurry, an electric-power generator, a heater, a preheater, a hydrochloric-acid reactor, a filter, a sodium-hydroxide reactor, a recovery equipment, and a peeling apparatus. The electric-power generator generates electric power using gas produced by hydrothermal treatment. The heater burns a portion of gas containing oxygen in the produced gas and heats the slurry. The preheater preheats the gas containing oxygen by using the exhaust heat of the electric-power generator. The recovery equipment recovers the deposits produced after reaction of filtrate and sodium-hydroxide aqueous solution. The peeling apparatus peels the biomass slurry adhered inside the reactor and heater.    DESCRIPTION OF DRAWING(S) - The drawing shows a flowchart of the phosphate recovery method. (Drawing includes non-English language text)