Method for preventing activated sludge from losing its settling ability.

摘要

A method for preventing activated sludge from losing its settling ability that appears sometimes in the solid/liquid separation in an activated sludge treatment of an aqueous organic waste and causes the so-called bulking and scumming of the sludge, which method comprises addiing either (a) a nonionic and/or an anionic surfactant, (b) a combination of a nonionic surfactant with a cationic surfactant of a form of quaternary ammonium salt or (c) a combination of a nonionic surfactant and a cationic surfactant of a form of a quaternary ammonium salt with a cationic organic flocculant, to the activated sludge treatment system.