Brief description of the treatment of waters holding by flocculation posterior to treatment with the sludge activated-

摘要

Process for waste water treatment comprising treating the supernatant stream from an active sludge treatment by a two- stage flocculation, comprises: (i) adding a mineral flocculating agent and adjusting the pH of the water to 4-5; (ii) maintaining this pH for - 1 minute; (iii) adjusting the pH to 5.5-9; (iv) adding an anionic polymeric flocculating agent, and (v) separating the flocculated material to produce a clarified supernatant stream.