PROCESS FOER RENING AV AVFALLSVATTEN.

摘要

A process for purifying waste water resulting from the manufacture of chemo- and/or thermomechanical pulp, which comprises subjecting the waste water to at least the following sequence of steps: sedimentation of coarser constituents (4); cooling (6); detoxification (7); anaerobic hydrolysis and preacidification (l0) with addition of nutrient salts and readjustment of the redox potential; production of methane in a methane reactor (ll); aerobic purification and separation of biologic sludge (l2; l3), which is at least partly recycled to the detoxification step (7), in which process aerobic sludge is separated prior to the anaerobic hydrolysis step (l0).