title: Hybrid constructed wetlands for highly polluted river water treatment and comparison of surface- and subsurface-flow cells.
abstract: A series of large pilot constructed wetland (CW) systems were constructed near the confluence of an urban stream to a larger river in Xi'an, a northwestern megacity in China, for treating polluted stream water before it entered the receiving water body. Each CW system is a combination of surface-and subsurface-flow cells with local gravel, sand or slag as substrates and Phragmites australis and Typha orientalis as plants. During a one-year operation with an average surface loading of 0.053 m(3)/(m(2)·day), the overall COD, BOD, NH3-N, total nitrogen (TN) and total phosphorus (TP) removals were 72.7% ± 4.5%, 93.4% ± 2.1%, 54.0% ± 6.3%, 53.9% ± 6.0% and 69.4% ± 4.6%, respectively, which brought about an effective improvement of the river water quality. Surface-flow cells showed better NH3-N removal than their TN removal while subsurface-flow cells showed better TN removal than their NH3-N removal. Using local slag as the substrate, the organic and phosphorus removal could be much improved. Seasonal variation was also found in the removal of all the pollutants and autumn seemed to be the best season for pollutant removal due to the moderate water temperature and well grown plants in the CWs.
authors: Key Laboratory of Northwest Water Resource, Environment and Ecology, Ministry of Education Xi'an University of Architecture and Technology, Xi'an 710055, China.
authors: Yucong
authors: Y
authors: Zheng
authors: Key Laboratory of Northwest Water Resource, Environment and Ecology, Ministry of Education Xi'an University of Architecture and Technology, Xi'an 710055, China. Electronic address: xcwang@xauat.edu.cn.
authors: Xiaochang
authors: X
authors: Wang
authors: Key Laboratory of Northwest Water Resource, Environment and Ecology, Ministry of Education Xi'an University of Architecture and Technology, Xi'an 710055, China.
authors: Jiaqing
authors: J
authors: Xiong
authors: Key Laboratory of Northwest Water Resource, Environment and Ecology, Ministry of Education Xi'an University of Architecture and Technology, Xi'an 710055, China.
authors: Yongjun
authors: Y
authors: Liu
authors: School of Civil, Structural and Environmental Engineering, University College Dublin, Belfield, Dublin 4, Ireland. Electronic address: zycxauat@gmail.com.
authors: Yaqian
authors: Y
authors: Zhao
mesh_terms: D009930:Organic Chemicals / Q000302:isolation & purification; D010865:Pilot Projects; D012621:Seasons; D014872:Water Movements; D014873:Water Pollutants / Q000302:isolation & purification*; D018508:Water Purification; D053833:Wetlands
chemical_list: D009930:Organic Chemicals; D014873:Water Pollutants
keywords: constructed wetland; polluted river water; subsurface-flow; surface-flow; treatment