title: Enhanced nitrogen removal in constructed wetlands: effects of dissolved oxygen and step-feeding.
abstract: Four horizontal subsurface flow constructed wetlands (HSFCWs), named HSFCW1 (three-stage, without step-feeding), HSFCW2 (three-stage, with step-feeding), HSFCW3 (five-stage, without step-feeding) and HSFCW4 (five-stage, with step-feeding) were designed to investigate the effects of dissolved oxygen (DO) and step-feeding on nitrogen removal. High removal of 90.9% COD, 99.1% ammonium nitrogen and 88.1% total nitrogen (TN) were obtained simultaneously in HSFCW4 compared with HSFCW1-3. The excellent TN removal of HSFCW4 was due to artificial aeration provided sufficient DO for nitrification and the favorable anoxic environment created for denitrification. Step-feeding was a crucial factor because it provided sufficient carbon source (high COD: nitrate ratio of 14.3) for the denitrification process. Microbial activities and microbial abundance in HSFCW4 was found to be influenced by DO distribution and step-feeding, and thus improve TN removal. These results suggest that artificial aeration combined with step-feeding could achieve high nitrogen removal in HSFCWs.
authors: Key Laboratory of Marine Environmental Science and Ecology, Ministry of Education, Ocean University of China, Qingdao 266100, China. Electronic address: lifengmin@ouc.edu.cn.
authors: Fengmin
authors: F
authors: Li
authors: Key Laboratory of Marine Environmental Science and Ecology, Ministry of Education, Ocean University of China, Qingdao 266100, China.
authors: Lun
authors: L
authors: Lu
authors: School of Environment and Natural Resources, Renmin University of China, Beijing 100872, China.
authors: Xiang
authors: X
authors: Zheng
authors: School of Civil and Environmental Engineering, University of Technology Sydney, Broadway, NSW 2007, Australia.
authors: Huu Hao
authors: HH
authors: Ngo
authors: Shandong Key Laboratory of Water Pollution Control and Resource Reuse, School of Environmental Science & Engineering, Shandong University, Jinan 250100, China.
authors: Shuang
authors: S
authors: Liang
authors: School of Civil and Environmental Engineering, University of Technology Sydney, Broadway, NSW 2007, Australia.
authors: Wenshan
authors: W
authors: Guo
authors: Key Laboratory of Marine Environmental Science and Ecology, Ministry of Education, Ocean University of China, Qingdao 266100, China.
authors: Xiuwen
authors: X
authors: Zhang
mesh_terms: D000332:Aerobiosis / Q000187:drug effects; D000704:Analysis of Variance; D001419:Bacteria / Q000187:drug effects / Q000378:metabolism; D001673:Biodegradation, Environmental; D057919:Biological Oxygen Demand Analysis; D009584:Nitrogen / Q000302:isolation & purification*; D010100:Oxygen / Q000494:pharmacology*; D012212:Rheology / Q000187:drug effects; D014865:Waste Disposal, Fluid; D062065:Wastewater / Q000382:microbiology; D014874:Water Pollutants, Chemical / Q000302:isolation & purification; D053833:Wetlands
chemical_list: D009584:Nitrogen; D010100:Oxygen; D062065:Wastewater; D014874:Water Pollutants, Chemical
keywords: Constructed wetland; Denitrification; Dissolved oxygen; Nitrification; Step-feeding