Removal of Ethylenediaminetetraacetic acid (EDTA) from Pulp Mill Effluents by Ozonation

AbstractOzone application was investigated for its effectiveness in the removal of ethylenediaminetetraacetic acid (EDTA) from bleaching effluent. The objectives were to compare the efficiency of ozone reaction on Na-EDTA solution with pure Fe3+-EDTA complex and EDTA complexes in bleaching effluent, and to test if changing pH and addition of hydrogen peroxide (H2O2) increases the removal of EDTA. Small ozone doses destroyed high proportions of Na-EDTA. This effect was diminished when EDTA formed complexes with other metal ions. It was shown that EDTA present in bleaching effluent was more easily oxidizable than in pure Fe3+-EDTA solution. Variation of initial pH value had no significant influence on the removal of Na-EDTA. Addition of hydrogen peroxide did not increase degradation of EDTA in bleaching effluent.