Enhancement of nitrification in submerged flow constructed wetlands

Four laboratory-scale, submerged flow constructed wetland (SFCW) mesocosms (Juncus effesus) were used to evaluate methods of increasing oxygenation within the wetlands to enhance nitrogen removal from applied wastewaters. The SFCW containing a naturally aerated pool had the highest total nitrogen (TN) removal (90 percent) and lowest effluent TN concentration (3.5 mg/L). Lowest TN removals (15 percent) were obtained from a wetland containing a mechanically aerated pool. Nitrification of ammonia was achieved but low organic carbon levels inhibited denitrification, resulting in high levels of nitrate in the effluent. Juncus effesus preferred ammonia to nitrate and grew poorly in waters dominated by nitrate. Providing a naturally aerated pool within a SFCW appears to be an economical method of increasing oxygenation in constructed wetlands treating wastewater.Project # G-2029-01 Agreement # 14-08-0001-G-2029-0