Removal of organic carbon in water hyacinth constructed wetland

The microbial mechanisms of organic carbon removal in free water constructed wetland planted with water hyacinth were studied. Importance was given to the role of water hyacinth plants on removal of organic carbon in the wetland cell. A model incorporating the activities of both suspended and biofilm biomasses was developed with the intention of simulating various processes involved in the transformation and removal rate of COD in the water hyacinth constructed wetland. The major processes governing the organic carbon transformation and removal in a water hyacinth constructed wetland system were sedimentation of COD (56.5%), regeneration of organic carbon ( 25.5%) , oxidation of organic carbon to carbon dioxide (6.4%), plant decay (4.4%) and uptake of organic carbon by heterotrophic bacteria (4.2%). The COD removal percentage of the model when the effect of biofilm was considered was 40.5%. when the calibrated model was run without considering the effect of biofilm the COD removal percentage dropped to 34.0%. this confirms the significance of the water hyacinth roots as an attachment media, which is extremely biologically active in assisting the organic carbon removal in the water hyacinth constructed wetland.