NOVELTY - A water-soluble coolant (4) containing glycol as a main component, or water-soluble slurry containing water-soluble coolant is supplied to silicon-containing waste liquid (3). The recycled coolant and recycled silicon block (1) are obtained from waste liquid. The recycled coolant and solid content are separated by distilling waste liquid, or concentrated portion of waste liquid. The solid content for silicon collection, and liquid content are solid-liquid separated, after dispersing solid content in washing liquid (9) and washing.    USE - Processing of silicon-containing waste liquid discharged during manufacture of thin film used for silicon wafer for integrated circuit chip and solar-cell component.    ADVANTAGE - The method efficiently and economically recovers silicon from the silicon-containing waste liquid.    DETAILED DESCRIPTION - A water-soluble coolant containing glycol as a main component, or water-soluble slurry containing water-soluble coolant is supplied to silicon-containing waste liquid discharged by machining a silicon block using metal work samples, or concentrated portion of waste liquid. The recycled coolant and recycled silicon block are obtained from waste liquid. The recycled coolant and solid content are separated by distilling waste liquid, or concentrated portion of waste liquid. The solid content, and liquid content are solid-liquid separated, after dispersing solid content in washing liquid and washing. The solid content is dispersed in basic aqueous solution, and washed. The solid content in aqueous acid (19,20) is washed by adding aqueous acid to basic aqueous solution, without solid-liquid separating basic aqueous solution and solid content.    DESCRIPTION OF DRAWING(S) - The drawing shows the apparatus for processing of silicon-containing waste liquid. (Drawing includes non-English language text)    Silicon block (1)    Waste liquid (3)    Water-soluble coolant (4)    Regenerated coolant (5)    Washing liquid (9)    Aqueous acids (19,20)