TREATING METHOD FOR SLURRY WASTE LIQUID

PROBLEM TO BE SOLVED: To provide a treating method for slurry waste liquid, which can treat a large amount of the slurry waste liquid properly at a low cost. SOLUTION: In a pH controlling tank 3, to which slurry waste liquid generated in a liquid crystal glass polishing process 1 is supplied, a predetermined chemical liquid is poured to adjust pH to about 3.5-7.0 in the vicinity of the isoelectric point of dispersed CeO2. The slurry waste liquid is then supplied to a charge treatment tank 5. In this first stage, the waste liquid is separated into a first supernatant containing a large amount of boron and a first precipitate containing a large amount of CeO2 and SiO2. The first precipitate is returned to the pH controlling tank 3 again, and at this time, pH is adjusted to >=10 and the waste liquid is subjected to charge treatment again. In this second stage, the waste liquid is separated into a second supernatant containing a large amount of SiO2 and a second precipitate containing a large amount of CeO2.