Vertical Constructed Wetlands Integrated with Biochar: A Green Nature-Based Solution for Wastewater Treatment

Efficient wastewater treatment is crucial before its discharge into natural water bodies or reuse. Constructed wetlands (CWs) are an attracting sanitation technology for wastewater treatment, offering low external energy requirements, aesthetic value and ease of operation. Biochar, with its unique physicochemical properties, is a strong multifunctional medium in CWs having a good capacity to adsorb micropollutants with supporting plant growth, and to provide suitable environment for microbial communities. This study evaluates the removal efficiency of key parameters (COD, NH₄⁺–N, NO₂⁻–N, NO₃^–N) and certain pharmaceutical compounds (PhCs) and their transformation products (TPs) in a vertical-flow, planted with Phragmites Australis and containing biochar (CW-BC-P). The removal efficiency of this system was compared to that of an unplanted biochar-filled constructed wetland (CW-BC-U) and a planted constructed wetland containing gravel instead of biochar (CW-G-P). All CWs were experimented using urban wastewater. The main results show that vertical CWs play a significant role in the reduction of the concentrations of the studied PhCs for which obtained removal rates were between 50 and 100%, and also in the reduction of COD (R_COD were between 60 and 71%). CW-BC-U performed higher removal efficiency for some PhCs by comparing with planted systems confirming that the integration of biochar into the CW plant enhances the performances of the wastewater treatment system.