METHOD OF PROCESSING EXCESS ACTIVATED SLUDGE CONTAINING HEAVY METALS Russian patent published in 1999 - IPC

FIELD: methods of processing excess activated sludge of sewage waters containing heavy metals at biological sewage disposal plants. SUBSTANCE: method includes thickening of activated sludge and mixing with material containing difficulty soluble calcium salts in the form of natural materials or industrial wastes in ratio of 5-15 parts of material per 100 parts of sludge. Mixture is agitated for 3-6 h at temperature of 6-30 C and separated into solid water phases, with water phase containing heavy metals. Stages of mixing and agitation may be performed before stage of thickening. Heavy metals are recovered from aqueous phase by reagent precipitation, ion exchange or absorption method. EFFECT: simplified process of recovery of heavy metals from sludge subsequent utilization of organic matter of sludge in agriculture. 3 cl, 1 tbl