Method for direct selection of a predetermined low sludge index by means of external sludge selection within an activated sludge method

摘要

Waste water treatment method comprises: feeding activated sludge from a continuous activated sludge or sequential batch reactor plant into a settling tank;#allowing the sludge to settle;#removing an upper fraction which has a high sludge index as overflow;#passing the lower fraction with a low sludge index to another tank; and#determining the sludge index of this fraction. This process is repeated until sludge index of the lower fraction reaches a predetermined low value.