Complexing agents are industrial chemicals used for many purposes in and by industry and trade, but also by households and are often discharged into our water bodies. Complexing agents are used by the chemical industry, the paper and photo industry, the beverage dispensing industry and beverage producers, by the textile industry, diary industry and galvanic industry (finishing of metal surfaces).
In our water bodies, complexing agents are regularly determined in concentrations varying between one-digit and double digit micrograms per litre (µg/l) and apart from DTPA their occurrence increases downstream the Rhine. The highest concentrations are measured in the Lower Rhine and the Delta Rhine and in several Rhine tributaries.
The evaluation report consists of a more in depth consideration of the artificially produced complexing agents EDTA and DTPA. In the Rhine and its tributaries they are detected in higher concentrations.
Complexing agents are of concern to drinking water providers, as they cannot be completely eliminated in wastewater treatment plants. There are no effects to be expected on organisms in the Rhine. Eventual detrimental environmental effects will rather occur due to interaction with other substances (in particular heavy metals, such as cadmium and mercury or other hardness components). Thus the heavy metal discharge of wastewater treatment plants into surface waters may increase.
In order to effectively reduce the pollution of water bodies and drinking water with complexing agents, measures at the source must be taken; extending wastewater treatment plants by further treatment procedures will not have the required effect.
