Abstract

The EDTA concentration in Dutch surface and drinking waters varies from 0-40 mug/l. The reduction during water treatment is 0 to 25-50% (when ozone is applied). Based on stoichiometry 40 mug/l EDTA can complex maximally 4-15 mug/l metals. In view of the present standards, this could only pose problems with respect to Cu and Cd. From speciation-calculations with the computerprogram Titrator, it appears however that at the present levels of metals and EDTA, the EDTA is dominantly present as Ni-EDTA complex. EDTA does not have any effect on the leaching of Cu in view of the high solubility of copperhydroxides and carbonates. The effect on the possible leaching of Cd is limited as the EDTA is primarily bound to other metals (Ni, Ca, Zn) at the present concentrations. Nevertheless the consumption of EDTA should not be increased and biodegradable alternatives should be found.