NOVELTY - A black liquor is processed by production process which makes functional group of component molecule contained in black liquor into electronic excited state, induces photochemical reaction and produces acid and volatile organic from organic matter component in black liquor, and separation process which separates and acquires acid and volatile organic from liquid obtained from black liquor after production process using different vaporization temperature with characteristics and liquid component with acid which tends to gasify, acid and volatile substance.    USE - Processing of black liquor.    ADVANTAGE - The method significantly reduces heat radiation energy from combustion installation, energy consumption in black liquor regenerative cycle, pulp manufacturing process and whole paper manufacture process, consumption loss of fossil fuel of fossil fuel boiler and cost.    DETAILED DESCRIPTION - A black liquor is processed by providing residence time which adjusts intensity and irradiation time of electromagnetic waves where photochemical reaction is fully obtained by irradiating electromagnetic waves with UV light wavelength of 200 nm to infrared light wavelength of 900 nm in black liquor, production process which makes functional group of component molecule contained in black liquor into electronic excited state, induces photochemical reaction and produces acid and volatile organic from organic matter component in black liquor, separation process which separates and acquires acid and volatile organic from liquid obtained from black liquor after production process using different vaporization temperature with characteristics and liquid component with acid which tends to gasify, acid and volatile substance, oxidizing cooking liquor component after digestion process (301) by cooking liquor containing sodium polysulfides, caustic soda (NaOH), sodium sulfide (Na2S), sodium carbonate (Na2CO3) and sodium sulfate (Na2SO4) as main component, and collecting black liquor together with resin component derived from wood. INDEPENDENT CLAIMS are included for:    (1) black liquor processing apparatus; and    (2) electric power generation system.    DESCRIPTION OF DRAWING(S) - The drawing shows a flowchart of the black liquor processing method. (Drawing includes non-English language text).    Caustification process (100)    Digestion stage (301)