Influence of COD-fractions on removal effectiveness and accumulation of organic matter in constructed wetlands

The effect of the different type of organic substance present in sewage on the organic matter accumulation and removal effectiveness in the hybrid constructed wetlands has been analysed.Effectiveness of organic matter removal from domestic sewage in hydrophyte beds depends on the type of organic matter fractions and their concentrations. Basing on analysis of COD fractions (soluble and suspended easy-to-decompose and hard-todecompose fractions) it was proven that accumulation of organic matter in hydrophyte beds is determined by hard-to-decompose suspended fraction. Colmatation in the HF-CW beds was observed for the loads over 10.0 CODXsg m−2 d−1, while in the VF-CW beds – for the loads over 12.5 CODXsg m−2 d−1.