GB716886A - Improvements in or relating to the separation of phenols from waste water - Google Patents

Abstract

Phenols are separated from phenol-containing waters or aqueous solutions, especially waste waters from fuel distillation, hydrogenation, synthetic phenol and the like plants in at least four (advantageously six to twelve) stages in counter-current utilizing non-saponifiable solvents such as hydrocarbons, ethers, ketones, nitrogen bases or mixtures of two or more of these substances or two or more of these substances or mixtures of substances in succession in at least 5 per cent by volume, referred to the liquid to be treated and advantageously 10 to 20 per cent, the charged solvent being regenerated practically free from phenol by treatment with alkalis, their aqueous solutions or excess alkalis or preferably by distillation of the charged solvent and treatment of the distillate with said alkalis and reused. The waters which have been extracted down to a phenol content of about 100 milligrams or less per litre are extracted in one or more further extraction stages with the same or another solvent advantageously non-saponifiable, using larger quantities of solvent than in the first stages, the regeneration of the solvent or solvents being effected with alkalis. The small quantities of phenolate liquors obtained after separation from the bulk of the phenols taken up, may be added after acidification by mineral acds, e.g. carbon dioxide, to the waste water to be treated.ALSO:Phenols are separated from phenol-containing waters or aqueous solutions, especially waste waters from fuel distillation, hydrogenation, synthetic phenol and the like plants in at least four (advantageously six to twelve) stages in countercurrent utilizing non-vaporizable solvents such as hydrocarbons, ethers, ketones, nitrogen bases or mixtures of two or more of these substances or two or more of these substances or mixtures of substances in succession in at least 5 per cent by volume, referred to the liquid to be treated, and advantageously 10 per cent to 20 per cent, the charged solvent being regenerated practically free from phenol by treatment with alkalia, their aqueous solutions or excess alkalic or preferably by distillation of the charged solvent and treatment of the distillate with said alkalia and reused. The waters which have been extracted down to a phenol content of about 100 milligrams or less per litre are extracted in one or more further extraction stages with the same or another solvent advantageously non-vaporizable, using larger quantities of solvent than in the first stages, the regeneration of the solvent or solvents being effected with alkalis. The small quantities of phenolate liquors obtained after separation from the bulk of the phenols taken up, may be added after acidification by mineral acids, e.g. carbon dioxide, to the waste water to be treated.