Degradation of EDTA and novel complexing agents in pulp and paper mill process and waste waters by Fenton's reagent

Fenton's process was used in oxidative degradation of ethylediaminetetraacetic acid (EDTA) and novel complexing agents, namely BCA5 and BCA6, in distilled water and spiked samples of integrated pulp and paper mill waste water and ECF-pulp bleaching effluent. In waste water, over 90% of EDTA was degraded within 3 min when temperature was 60 °C, pH 4, and molecular ratio of H₂O₂:Fe²⁺:EDTA was 70:2:1 (0.26 mM EDTA) or higher. In spiked ECF bleaching effluent up to 42% of EDTA was degraded in similar reaction conditions, still higher than published results indicate biological waste water treatment of pulp and paper mill waste water being capable of. In pH 3, EDTA proved readily degradable by Fenton's process in otherwise similar conditions. According to these results, Fenton's process could be used as a pre-treatment method for EDTA-containing bleaching effluents prior to the biological waste water treatment. In addition, BCA5 and BCA6 proved their superiority in terms of degradability also by Fenton's process in both pH 3 and 4.