TREATMENT METHOD FOR WASTE WATER SLUDGE COMPRISING AT LEAST ONE METAL

摘要

A method for treating waste water sludge comprising at least one metal originating from a waste water treatment coagulant, and phosphorus and heavy metals in order to recover said at least one metal and phosphorus and to discharge said heavy metals, said method comprising: acidifying said waste water sludge to dissolve metals contained in the sludge; subjecting the acidified waste water sludge to liquid-liquid extraction for recovering at least a portion of said at least one metal; treating the raffinate of the extraction in a first precipitation stage with appropriate chemicals for precipitating heavy metals, and thereafter discharging the precipitate thereby leaving a solution having a decreased content of heavy metals; and treating the solution having a decreased content of heavy metals in a second precipitation stage with appropriate chemicals for precipitating phosphorus and thereafter recovering the precipitated phosphorus.