TECHNOLOGY FOCUS - BIOTECHNOLOGY - Preferred Method: The water-reactive anhydride and/or water-containing biomass is continuously injected into the reactor to maintain or to increase the temperature in the closed reactor, where the amount of water in the biomass is 0.5-3 times the dry weight of the biomass. The internal reactor temperature is increased from 60 degrees C to 130 degrees C by the internal heating process. The water-reactive anhydride has pressure of 10 psi-500 psi, preferably 20 psi-130 psi. The water-reactive anhydride dissolves or hydrolyzes at least one component of the biomass. The water-reactive anhydride is a basic or acidic gas. The water-reactive anhydride is chosen from anhydrous ammonia, hydrogen sulfide, hydrogen chloride, carbon dioxide and their mixtures. The method further involves preparing the water-containing biomass by supplying water. The method further involves removing lignin extracted from the pretreated biomass, where the amount of lignin removed is 30% or more than the initial amount of lignin present in the biomass. The method further involves adding a solvent to the biomass to dissolve hemicellulose and/or cellulose, and extracting hemicellulose and/or cellulose from residual solid components of the biomass.    TECHNOLOGY FOCUS - INSTRUMENTATION AND TESTING - Preferred Apparatus: The biomass supply unit, reaction unit and separation unit are continuously formed, and a screw-type transfer apparatus is formed inside to transfer the biomass continuously. The apparatus further comprises a water supply unit formed between the biomass supply unit and reaction unit to supply water to the biomass. The outer surface of the reaction unit is insulated. The apparatus further comprises a first supply tank containing a fresh water-reactive anhydride connected to the inlet portion. The apparatus further comprises a fragmentation portion formed between the biomass supply unit and the reaction unit to fragment the biomass. The apparatus further comprises a bridge portion formed between the outlet portion and the inlet portion to transfer fluid from the outlet portion to the inlet portion. The bridge portion includes a dehydration column and/or a compressor. The apparatus further comprises a second supply tank in fluid connection with the dehydration column and/or the compressor. The apparatus further comprises a mixing unit in fluid connection with the first supply tank, second supply tank, and inlet portion. The outlet portion includes an exhaustion portion, which is separated from the bridge portion to exhaust a vapor generated by the internal heating process. The apparatus further comprises a washing unit connected to the reaction unit to wash the biomass. EXAMPLE - No suitable example given.