Seasonal Variation of Nutrient Removal in a Full-Scale Artificial Aerated Hybrid Constructed Wetland

To improve nutrient removal, a full-scale hybrid constructed wetland (CW) consisting of pre-treatment units, vertical-baffled flow wetlands (VBFWs), and horizontal subsurface flow wetlands (HSFWs) was installed in August 2014 to treat sewage wastewater. Artificial aeration (AA) was applied continuously in the VBFW stage to improve the aerobic condition in the hybrid CW. Water samples were collected and analyzed twice a month between the period of August 2015 and July 2016. The results suggest that this new hybrid CW can achieve a satisfactory reduction of chemical oxygen demand (COD), ammonium nitrogen (NH4-N), total nitrogen (TN), and total phosphorus (TP) with average removal rates of 85% ± 10% (35% ± 19 g/m2 per day), 76% ± 18% (7% ± 2 g/m2 per day), 65% ± 13% (8% ± 2 g/m2 per day), and 65% ± 21% (1 g/m2 per day), respectively. AA significantly improved the aerobic condition throughout the experimental period, and the positive influence of AA on nitrogen removal was found to be higher during summer that during winter. A significant positive correlation between water temperature and nutrient removal (p < 0.01) was observed in the system. Overall, this study demonstrates the application of AA in a full-scale hybrid CW with satisfactory nutrient removal rates. The hybrid CW system with artificial aeration can serve as a reference for future applications areas where land availability is limited.