METHOD OF EXTRACTION OF HEAVY METALS FROM EXCESSIVE ACTIVATED SLUDGE Russian patent published in 2001 - IPC

FIELD: processing of excessive activated sludge of biological structures for purification of sewage containing heavy metals. SUBSTANCE: activated sludge is thickened, soluble phosphates are added in amount of 1-100 mg of PO^-3 per 1 liter of activated sludge and the whole is agitated with low-soluble calcium salts in the form of natural minerals or production waste at 6-30 C. Solid and liquid phases are separated by settling, and/or centrifugation and/or filtration, and heavy metals are extracted from aqueous phase by methods of reagent deposition or ionic exchange or adsorption. Calcium material includes tricalcium phosphates or natural phosphates. Process over, solid phase is separated from microorganisms of activated sludge and aqueous phase by settling. Calcium material is washed with water. Washed solid phase is recycled to heavy metal isolation stage, and water is recycled for settling of heavy metals. EFFECT: increased rate of isolation of heavy metals from activated sludge and lower consumption of calcium-containing materials. 3 cl, 12 ex, 1 tbl