Competitive adsorption of micropollutants and NOM onto activated carbon: comparison of different model approaches

Conventional adsorption models are not able to describe exactly the competitive adsorption of natural organic matter (NOM) and micropollutants during drinking water treatment with activated carbon. This problem is a consequence of the complex structure of natural organic matter. In the last years, two user-oriented model approaches, the tracer model (TRM) and the equivalent background compound model (EBCM), were proposed to overcome the difficulties in modelling the competitive adsorption in such multi-component systems. In this paper, these model approaches, as well as a simplified model for batch processes, are compared and opportunities and limitations are pointed out. The different aspects of model application are exemplarily discussed for the adsorption of two pesticides, atrazine and diuron, from Elbe River water onto activated carbon. As can be seen from the examples and from a series of studies, both models are suitable for modelling the micropollutant adsorption in the presence of NOM. The EBCM is somewhat easier to handle whereas the TRM allows for the consistent and parallel description of micropollutant and NOM adsorption.