Abstract: A method is disclosed for removing heavy metals from a solution of waste or effluent containing chelating agents such as ethylenediamine tetraacetic acid (EDTA), 1,2-cyclohexanediamine tetraacetic acid(CDTA), and citric acid(Citrate), comprising: acidifying the solution with nitric acid, and oxidization of the acidified solution under controlled pressure and temperature. Upon oxidation, the heavy metal chelate (EDTA-m, CDTA-m or Citrate-m) is decomplexed, and heavy metal ions are liberated and can be precipitated using a conventional precipitation method such as by treatment with lime and a flocculent.