DECOLORING TREATING METHOD OF DYEING WASTE WATER

摘要

PURPOSE:To de-dye the dyeing waste water to colorless and transparent one and perform sedimentation-separation in a short time by mixing the dyeing waste water and Al(OH)3 and Al2O3 or further water-insoluble Ca salt in an alkaline region of the specified pH then neutralizing the same by acids. CONSTITUTION:The dyeing waste water and Al(OH)3 and Al2O3 or further water- insoluble Ca salt such as CaCO3 are mixed at a ratio of Al salt: water-insoluble Ca salt =3:1-1:3 (molar ratio) to pH or more, preferably about 9-10. Thence, this mixed solution is neutralized by acids and the sludge formed is separated and this is recycled for the decoloring of the dyeing waste water directly or after it has been heated to 100-450 deg.C. This method enables the removal of the dyes of the dyeing waste water to 99.9% or more and nevertheless makes possible the recycling of the sludge, obviates the production of sludge waste and enables the operation in a closed system.