Abstract: Hydrogen is produced from a cellulose-containing biomass by heating the biomass in the presence of water and a catalyst at a temperature of 250.degree.-374.degree. C. and at a pressure higher than the saturated vapor pressure of water. The catalyst includes a catalytic metal selected from the group consisting of nickel, iron, cobalt, molybdenum, tungsten, platinum and mixtures thereof.

Abstract: Water containing an inorganic nitrogen-containing compound, such as water effluent from sewage treatment plant, is treated for the removal of the nitrogen-containing compound and for the production of hydrocarbons by proliferating microalga capable of consuming the nitrogen-containing compound and of producing the hydrocarbons as an intracellular product. After adjusting the water content, the resulting culture containing the proliferated microalga and clean water is heated at a high temperature and a high pressure to liberate the hydrocarbon from the microalga. The hydrocarbon is subsequently recovered by solvent extraction.

Abstract: A cellulose-containing biomass such as wood is liquefied by heat-treatment under a pressurized condition in the presence of water and a neutral, oxygen-containing organic liquid such as an ester, ether, ketone or alcohol. An alkaline catalyst such as potassium carbonate may be added to accelerate the liquefaction when the organic liquid is one other than acetone. Also provided is a process for the liquefaction of a cellulose-containing biomass including heat-treating the biomass in an aqueous medium in the pressurized atmosphere of an inert gas or steam at a temperature of 250.degree.-385.degree. C. in the presence of an alkaline catalyst in an amount of 0.01-0.1 part by weight per one part by weight of the biomass on the dry basis.