To enhance the nitrate removal in constructed wetlands (CWs) for treating hydroponic wastewater dis-charged from greenhouses, the effectiveness of HF (horizontal flow)-HF hybrid CWs utilizing a combinedsulfur-based autotrophic (based on the optimum conditions from batch experiment) and heterotrophicdenitrification was evaluated for treating hydroponic wastewater containing high nitrate and low organiccarbon concentrations.