The fate of carbon nanotubes (CNT) in the environment will be governed by the presence of natural dissolved organic matter (DOM). Many studies indicate that CNT create stabilized suspensions in the presence of DOM. Easier transport in the environment may indicate their greater hazard. However these studies describe the interactions of DOM with as produced CNT. In the present studies the interactions of UV and/or H2O2 treated wastewater containing CNTOH or CNTCOOH with the naturally occurred fulvic acids (FA) were presented. FA sorption, both kinetics and mechanism, were described using batch regime. The sorption of FA followed a pseudo-second order kinetics and was described with the highest accuracy by Langmuir or Dubinin-Radushkevich model for CNTOHs and Langmuir, Temkin or Dubinin-Radushkevich - for CNTCOOHs. The mechanism of FA sorption onto CNTOHs was ascribed to π-π, heterogeneous and electrostatic interactions. The π-π and electrostatic interactions can the mostly defined FA adsorption onto CNTCOOHs. The parameters affecting FA sorption were combination of porosity and dispersity.