Process for purification of waste waters accumulated from pulp production, particularly from chlorine bleaching of pulp

Abstract

Abstract There is disclosed a process for purification of waste waters accumulating from the production of pulp, particularly from chlorine bleaching of pulp, which comprises the combination of the following steps: (a) release of solid particles from the waste water in a series-connected, mechanical purification stage, (b) introduction of the pre-cleaned waste water into an electrolysis installation, wherein the waste water is subjected to constant movement during an anodic oxidation treatment, and an electric potential differential is plotted between the electrodes and the pH of the waste water is set and maintained at approximately 1 to 6.5 in a known manner, (c) transfer of the waste water thus treated from stage (b) into a flocculation (sedimentation) zone, in which an aqueous solution of a powerful cationic polyelectrolyte is fed to the waste water at room temperature and under constant movement, and the pH is set and maintained at 1 to 6.5, and flocculation of colloids and suspended components occurs, (d) transfer of the waste water thus treated together with the flocculated products from stage (c) into another zone, in which the flocculated products are separated out, (e) neutralization of the waste water which is freed of the flocculated products, and (f) transfer of the neutralized waste water into an activated sludge installation, in which, with addition of additive nutrient materials, suitable microorganisms cause biological decomposition of the organic products still present in the waste water, whereupon the waste water which is thus clarified is discharged into a receiving stream.

Inventors

• 👤 Dieter J. Becker

Bibliographic Details