The background organics in water and wastewater are necessary to fractionate into groups or components according to the difference in adsorbability. In this study, the background organics were fractionated in terms of the adsorptive strength described by the Freundlich isotherm constants k and n with the assumption that the fractionated components differ in the value of k but have the same value of n based on the IAST (Ideal Adsorption Solution Theory) using binomial concentration distribution. A simple characterization for water and wastewater with a certain amount of DOC in terms of adsorbability was applied to three types of organic mixtures contained in different water sources. The composition of each organic mixture was successfully evaluated to describe the IAE (Integral adsorption experiments) data of the total organic carbon by using this characterization procedure. Batch experiments as well as the membrane-PAC hybrid system experiments were conducted with three different types of PACs.