EXTRACTION OF HEAVY METAL FROM SLUDGE

摘要

PROBLEM TO BE SOLVED: To extract heavy metals from sludge by simple operation to prepare org. fertilizer. SOLUTION: A slurry 4 prepared by adding water 3 to sludge 2 is set to treatment temp. of 30-90 deg.C and adjusted to pH 8-11 to elute and extract heavy metals from sludge 2. When the concn. of an ammonium salt is 1,000 ppm or less, an ammonium salt containing HCO3- or Cl- as anions or an ammonium salt mixture is added to the slurry 4 or a gas containing an ammonia gas is introduced into the slurry 4 to enhance the concn. of an ammonium salt.