Treatment of waste containing EDTA by chemical oxidation

摘要

Ethylenediaminetetraacetic acid (EDTA) is a chelating agent that has been extensively used to enhance the solubilization of heavy metal cations and release of EDTA contributes to environmental problems. EDTA is recalcitrant to microbial metabolism and chemical oxidation is considered a possible method of remedial treatment. The use of the commercially available process of MIOX Corporation generates mixed oxidants on site and this solution is markedly effective in the destruction of the chelating characteristic and the decarboxylation of EDTA. When measuring the release of C-14 from carboxyl labeled EDTA, the mixed oxidant solution was comparable to the Fenton's reaction over a broad pH range. The presence of Mn~(2+), Cr~(3+), or Fe~(3+) at levels equal to that of EDTA stimulated the rate of EDTA decomposition; however, the rate of EDTA breakdown was inhibited when the concentration of Cr~(3+) or Mn~(2+) exceeded the concentration of EDTA. The treatment of Co~(2+)-EDTA or Cu~(2+)-EDTA with mixed oxidants in the presence of ultra violet light resulted in the loss of chelation ability of EDTA. In the absence of chelated metals, over 75/100 of the chelation property of a 70 mM EDTA solution was destroyed in 45 min. The reaction products resulting from the use of mixed oxidants added to EDTA were non-toxic to bactena and should not contribute to additional environmental problems.