Method of removing nitrogen impurities from water using hydrocarbon-producing microalga

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. Preferably the method of treating water for nitrogen impurities is carried out by culturing a proliferating hydrocarbon-producing microalga in contaminated water to obtain the proliferated microalga and purified water, then removing part of the purified water to obtain a first mixture containing the proliferated microalga and 60-98% by weight of water; further dissolving an alkaline substance in the first mixture to obtain a second mixture, applying heat to the second mixture in order to lyse and free the hydrocarbons from the microalga to form a third mixture. From the third mixture a free hydrocarbon product may be obtained.

Dependencies are inferred from the claim text.