Phosphate removal - from waste in sewage treatment process

摘要

In an activated sludge sewage treatment system, a mixed liquor is aerated to reduce its BOD content and to cause the organisms present to take up phosphate. The mixed liquor is then passed to a settling zone which contains an anaerobic layer of sludge. The phosphate enriched portions of the mixed liquor settle into this anaerobic layer thus causing the phosphate to be released as water-soluble ions into the liq. phase of the sludge. A phosphate depleted supernatant is discharged from this zone, and the sludge is removed for sepn. of the aq. phases contg. solid and low phosphate- concn. from a sludge having a high phosphate conc. The sludge having a reduced phosphate content can be recycled with the mixed liquor.