title: Performance of a pilot demonstration-scale hybrid constructed wetland system for on-site treatment of polluted urban river water in Northwestern China.
abstract: Hybrid constructed wetland (HCW) systems have been used to treat various wastewaters across the world. However, large-scale applications of HCWs are scarce, particularly for on-site improvement of the water quality of highly polluted urban rivers in semi-arid regions. In this study, a large pilot-scale HCW system was constructed to improve the water quality of the Zaohe River in Xi'an, China. With a total area of about 8000 m(2), the pilot HCW system, composed of different configurations of surface and subsurface flow wetlands, was operated for 2 years at an average inflow volume rate of 362 m(3)/day. Local Phragmites australis and Typha orientalis from the riverbank were planted in the HCW system. Findings indicate a higher treatment efficiency for organics and suspended solids than nutrients. The inflow concentrations of 5-day biochemical oxygen demand (BOD5), chemical oxygen demand (COD), suspended solids (SS), total nitrogen (TN), NH3-N, and total phosphorus (TP) were 125.6, 350.9, 334.2, 38.5, 27.2, and 3.9 mg/L, respectively. Average removal efficiencies of 94.4, 74.5, 92.0, 56.3, 57.5, and 69.2%, respectively, were recorded. However, the pollutant removal rates were highly seasonal especially for nitrogen. Higher removals were recorded for all pollutants in the autumn while significantly lower removals were recorded in the winter. Plant uptake and assimilation accounted for circa 19-29 and 16-23% of the TN and TP removal, respectively. Moreover, P. australis demonstrated a higher nutrient uptake ability and competitive potential. Overall, the high efficiency of the pilot HCW for improving the water quality of such a highly polluted urban river provided practical evidence of the applicability of the HCW technology for protecting urban water environments.
authors: Key Laboratory of Northwest Water Resource, Environment and Ecology, MOE, School of Environmental and Municipal Engineering, 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, MOE, School of Environmental and Municipal Engineering, Xi'an University of Architecture and Technology, Xi'an, 710055, China. xcwang@xauat.edu.cn.
authors: Xiaochang C
authors: XC
authors: Wang
authors: Key Laboratory of Northwest Water Resource, Environment and Ecology, MOE, School of Environmental and Municipal Engineering, Xi'an University of Architecture and Technology, Xi'an, 710055, China.|UCD Dooge Centre for Water Resources Research, School of Civil, Structural and Environmental Engineering, Newstead Building, University College Dublin, Belfield, Dublin 4, Ireland.
authors: Mawuli
authors: M
authors: Dzakpasu
authors: Key Laboratory of Northwest Water Resource, Environment and Ecology, MOE, School of Environmental and Municipal Engineering, Xi'an University of Architecture and Technology, Xi'an, 710055, China.
authors: Yuan
authors: Y
authors: Ge
authors: UCD Dooge Centre for Water Resources Research, School of Civil, Structural and Environmental Engineering, Newstead Building, University College Dublin, Belfield, Dublin 4, Ireland.
authors: Yaqian
authors: Y
authors: Zhao
authors: Key Laboratory of Northwest Water Resource, Environment and Ecology, MOE, School of Environmental and Municipal Engineering, Xi'an University of Architecture and Technology, Xi'an, 710055, China.
authors: Jiaqing
authors: J
authors: Xiong
mesh_terms: D000327:Adsorption; D001673:Biodegradation, Environmental; D057919:Biological Oxygen Demand Analysis; D002681:China; D009584:Nitrogen / Q000032:analysis / Q000378:metabolism; D010758:Phosphorus / Q000032:analysis / Q000378:metabolism; D006109:Poaceae / Q000378:metabolism*; D045483:Rivers / Q000737:chemistry*; D012621:Seasons; D032401:Typhaceae / Q000378:metabolism*; D062065:Wastewater / Q000032:analysis; D018508:Water Purification / Q000295:instrumentation / Q000379:methods*; D060753:Water Quality; D053833:Wetlands
chemical_list: D009584:Nitrogen; D010758:Phosphorus; D062065:Wastewater
keywords: Constructed wetland; Pollution; Seasonal performance; Urban river restoration